Merge github.com:grpc/grpc into bwest

209 files changed, 3064 insertions, 1389 deletions

diff --git a/src/compiler/python_generator.cc b/src/compiler/python_generator.cc
index 0fac1b88cd..4841da8da8 100644
--- a/src/compiler/python_generator.cc
+++ b/src/compiler/python_generator.cc
@@ -724,6 +724,9 @@ pair<bool, grpc::string> PrivateGenerator::GetGrpcServices() {
     out = &out_printer;
 
     if (generate_in_pb2_grpc) {
+      out->Print(
+          "# Generated by the gRPC Python protocol compiler plugin. "
+          "DO NOT EDIT!\n");
       if (!PrintPreamble()) {
         return make_pair(false, "");
       }
diff --git a/src/core/ext/README.md b/src/core/ext/README.md
new file mode 100644
index 0000000000..0812b20823
--- /dev/null
+++ b/src/core/ext/README.md
@@ -0,0 +1,5 @@
+Optional plugins for gRPC Core: Modules in this directory extend gRPC Core in
+useful ways. All optional code belongs here.
+
+NOTE: The movement of code between lib and ext is an ongoing effort, so this
+directory currently contains too much of the core library.
diff --git a/src/core/ext/census/grpc_plugin.c b/src/core/ext/census/grpc_plugin.c
index e43ceafd0c..c9fe453af8 100644
--- a/src/core/ext/census/grpc_plugin.c
+++ b/src/core/ext/census/grpc_plugin.c
@@ -51,7 +51,8 @@ static bool is_census_enabled(const grpc_channel_args *a) {
   return census_enabled();
 }
 
-static bool maybe_add_census_filter(grpc_channel_stack_builder *builder,
+static bool maybe_add_census_filter(grpc_exec_ctx *exec_ctx,
+                                    grpc_channel_stack_builder *builder,
                                     void *arg) {
   const grpc_channel_args *args =
       grpc_channel_stack_builder_get_channel_arguments(builder);
diff --git a/src/core/ext/census/tracing.c b/src/core/ext/census/tracing.c
index 8f0e12296d..3b5d6dab2b 100644
--- a/src/core/ext/census/tracing.c
+++ b/src/core/ext/census/tracing.c
@@ -31,19 +31,15 @@
  *
  */
 
-//#include "src/core/ext/census/tracing.h"
-
 #include <grpc/census.h>
 
 /* TODO(aveitch): These are all placeholder implementations. */
 
-// int census_trace_mask(const census_context *context) {
-//   return CENSUS_TRACE_MASK_NONE;
-// }
-
-// void census_set_trace_mask(int trace_mask) {}
+int census_trace_mask(const census_context *context) {
+  return CENSUS_TRACE_MASK_NONE;
+}
 
-// void census_trace_print(census_context *context, uint32_t type,
-//                         const char *buffer, size_t n) {}
+void census_set_trace_mask(int trace_mask) {}
 
-// void SetTracerParams(const Params& params);
+void census_trace_print(census_context *context, uint32_t type,
+                        const char *buffer, size_t n) {}
diff --git a/src/core/ext/client_channel/channel_connectivity.c b/src/core/ext/client_channel/channel_connectivity.c
index b10f444b63..dd70bc2c6c 100644
--- a/src/core/ext/client_channel/channel_connectivity.c
+++ b/src/core/ext/client_channel/channel_connectivity.c
@@ -76,6 +76,7 @@ typedef struct {
   gpr_mu mu;
   callback_phase phase;
   grpc_closure on_complete;
+  grpc_closure on_timeout;
   grpc_timer alarm;
   grpc_connectivity_state state;
   grpc_completion_queue *cq;
@@ -200,6 +201,8 @@ void grpc_channel_watch_connectivity_state(
   gpr_mu_init(&w->mu);
   grpc_closure_init(&w->on_complete, watch_complete, w,
                     grpc_schedule_on_exec_ctx);
+  grpc_closure_init(&w->on_timeout, timeout_complete, w,
+                    grpc_schedule_on_exec_ctx);
   w->phase = WAITING;
   w->state = last_observed_state;
   w->cq = cq;
@@ -208,7 +211,7 @@ void grpc_channel_watch_connectivity_state(
 
   grpc_timer_init(&exec_ctx, &w->alarm,
                   gpr_convert_clock_type(deadline, GPR_CLOCK_MONOTONIC),
-                  timeout_complete, w, gpr_now(GPR_CLOCK_MONOTONIC));
+                  &w->on_timeout, gpr_now(GPR_CLOCK_MONOTONIC));
 
   if (client_channel_elem->filter == &grpc_client_channel_filter) {
     GRPC_CHANNEL_INTERNAL_REF(channel, "watch_channel_connectivity");
diff --git a/src/core/ext/client_channel/client_channel.c b/src/core/ext/client_channel/client_channel.c
index a762b8917e..2f25fef9a7 100644
--- a/src/core/ext/client_channel/client_channel.c
+++ b/src/core/ext/client_channel/client_channel.c
@@ -83,8 +83,12 @@ static void *method_parameters_copy(void *value) {
   return new_value;
 }
 
+static void method_parameters_free(grpc_exec_ctx *exec_ctx, void *p) {
+  gpr_free(p);
+}
+
 static const grpc_mdstr_hash_table_vtable method_parameters_vtable = {
-    gpr_free, method_parameters_copy};
+    method_parameters_free, method_parameters_copy};
 
 static void *method_parameters_create_from_json(const grpc_json *json) {
   wait_for_ready_value wait_for_ready = WAIT_FOR_READY_UNSET;
@@ -328,7 +332,7 @@ static void on_resolver_result_changed(grpc_exec_ctx *exec_ctx, void *arg,
           grpc_service_config_create(service_config_json);
       if (service_config != NULL) {
         method_params_table = grpc_service_config_create_method_config_table(
-            service_config, method_parameters_create_from_json,
+            exec_ctx, service_config, method_parameters_create_from_json,
             &method_parameters_vtable);
         grpc_service_config_destroy(service_config);
       }
@@ -337,7 +341,7 @@ static void on_resolver_result_changed(grpc_exec_ctx *exec_ctx, void *arg,
     // be pointing to data inside chand->resolver_result.
     // The copy will be saved in chand->lb_policy_name below.
     lb_policy_name = gpr_strdup(lb_policy_name);
-    grpc_channel_args_destroy(chand->resolver_result);
+    grpc_channel_args_destroy(exec_ctx, chand->resolver_result);
     chand->resolver_result = NULL;
   }
 
@@ -358,7 +362,7 @@ static void on_resolver_result_changed(grpc_exec_ctx *exec_ctx, void *arg,
     chand->service_config_json = service_config_json;
   }
   if (chand->method_params_table != NULL) {
-    grpc_mdstr_hash_table_unref(chand->method_params_table);
+    grpc_mdstr_hash_table_unref(exec_ctx, chand->method_params_table);
   }
   chand->method_params_table = method_params_table;
   if (lb_policy != NULL) {
@@ -554,7 +558,7 @@ static void cc_destroy_channel_elem(grpc_exec_ctx *exec_ctx,
   gpr_free(chand->lb_policy_name);
   gpr_free(chand->service_config_json);
   if (chand->method_params_table != NULL) {
-    grpc_mdstr_hash_table_unref(chand->method_params_table);
+    grpc_mdstr_hash_table_unref(exec_ctx, chand->method_params_table);
   }
   grpc_connectivity_state_destroy(exec_ctx, &chand->state_tracker);
   grpc_pollset_set_destroy(chand->interested_parties);
@@ -1001,8 +1005,8 @@ static void read_service_config(grpc_exec_ctx *exec_ctx, void *arg,
     gpr_mu_unlock(&chand->mu);
     // If the method config table was present, use it.
     if (method_params_table != NULL) {
-      const method_parameters *method_params =
-          grpc_method_config_table_get(method_params_table, calld->path);
+      const method_parameters *method_params = grpc_method_config_table_get(
+          exec_ctx, method_params_table, calld->path);
       if (method_params != NULL) {
         const bool have_method_timeout =
             gpr_time_cmp(method_params->timeout, gpr_time_0(GPR_TIMESPAN)) != 0;
@@ -1025,7 +1029,7 @@ static void read_service_config(grpc_exec_ctx *exec_ctx, void *arg,
           gpr_mu_unlock(&calld->mu);
         }
       }
-      grpc_mdstr_hash_table_unref(method_params_table);
+      grpc_mdstr_hash_table_unref(exec_ctx, method_params_table);
     }
   }
   GRPC_CALL_STACK_UNREF(exec_ctx, calld->owning_call, "read_service_config");
@@ -1066,8 +1070,8 @@ static grpc_error *cc_init_call_elem(grpc_exec_ctx *exec_ctx,
       grpc_mdstr_hash_table *method_params_table =
           grpc_mdstr_hash_table_ref(chand->method_params_table);
       gpr_mu_unlock(&chand->mu);
-      method_parameters *method_params =
-          grpc_method_config_table_get(method_params_table, args->path);
+      method_parameters *method_params = grpc_method_config_table_get(
+          exec_ctx, method_params_table, args->path);
       if (method_params != NULL) {
         if (gpr_time_cmp(method_params->timeout,
                          gpr_time_0(GPR_CLOCK_MONOTONIC)) != 0) {
@@ -1080,7 +1084,7 @@ static grpc_error *cc_init_call_elem(grpc_exec_ctx *exec_ctx,
               method_params->wait_for_ready;
         }
       }
-      grpc_mdstr_hash_table_unref(method_params_table);
+      grpc_mdstr_hash_table_unref(exec_ctx, method_params_table);
     } else {
       gpr_mu_unlock(&chand->mu);
     }
@@ -1109,7 +1113,7 @@ static void cc_destroy_call_elem(grpc_exec_ctx *exec_ctx,
                                  void *and_free_memory) {
   call_data *calld = elem->call_data;
   grpc_deadline_state_destroy(exec_ctx, elem);
-  GRPC_MDSTR_UNREF(calld->path);
+  GRPC_MDSTR_UNREF(exec_ctx, calld->path);
   GRPC_ERROR_UNREF(calld->cancel_error);
   grpc_subchannel_call *call = GET_CALL(calld);
   if (call != NULL && call != CANCELLED_CALL) {
diff --git a/src/core/ext/client_channel/client_channel_factory.c b/src/core/ext/client_channel/client_channel_factory.c
index 4eb35dfcf7..d2707a1556 100644
--- a/src/core/ext/client_channel/client_channel_factory.c
+++ b/src/core/ext/client_channel/client_channel_factory.c
@@ -61,12 +61,10 @@ static void* factory_arg_copy(void* factory) {
   return factory;
 }
 
-static void factory_arg_destroy(void* factory) {
+static void factory_arg_destroy(grpc_exec_ctx* exec_ctx, void* factory) {
   // TODO(roth): Remove local exec_ctx when
   // https://github.com/grpc/grpc/pull/8705 is merged.
-  grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
-  grpc_client_channel_factory_unref(&exec_ctx, factory);
-  grpc_exec_ctx_finish(&exec_ctx);
+  grpc_client_channel_factory_unref(exec_ctx, factory);
 }
 
 static int factory_arg_cmp(void* factory1, void* factory2) {
diff --git a/src/core/ext/client_channel/client_channel_plugin.c b/src/core/ext/client_channel/client_channel_plugin.c
index a3e5079843..d50bba60f6 100644
--- a/src/core/ext/client_channel/client_channel_plugin.c
+++ b/src/core/ext/client_channel/client_channel_plugin.c
@@ -38,17 +38,20 @@
 #include <grpc/support/alloc.h>
 
 #include "src/core/ext/client_channel/client_channel.h"
+#include "src/core/ext/client_channel/http_connect_handshaker.h"
 #include "src/core/ext/client_channel/lb_policy_registry.h"
 #include "src/core/ext/client_channel/resolver_registry.h"
 #include "src/core/ext/client_channel/subchannel_index.h"
 #include "src/core/lib/surface/channel_init.h"
 
-static bool append_filter(grpc_channel_stack_builder *builder, void *arg) {
+static bool append_filter(grpc_exec_ctx *exec_ctx,
+                          grpc_channel_stack_builder *builder, void *arg) {
   return grpc_channel_stack_builder_append_filter(
       builder, (const grpc_channel_filter *)arg, NULL, NULL);
 }
 
-static bool set_default_host_if_unset(grpc_channel_stack_builder *builder,
+static bool set_default_host_if_unset(grpc_exec_ctx *exec_ctx,
+                                      grpc_channel_stack_builder *builder,
                                       void *unused) {
   const grpc_channel_args *args =
       grpc_channel_stack_builder_get_channel_arguments(builder);
@@ -66,9 +69,10 @@ static bool set_default_host_if_unset(grpc_channel_stack_builder *builder,
     arg.key = GRPC_ARG_DEFAULT_AUTHORITY;
     arg.value.string = default_authority;
     grpc_channel_args *new_args = grpc_channel_args_copy_and_add(args, &arg, 1);
-    grpc_channel_stack_builder_set_channel_arguments(builder, new_args);
+    grpc_channel_stack_builder_set_channel_arguments(exec_ctx, builder,
+                                                     new_args);
     gpr_free(default_authority);
-    grpc_channel_args_destroy(new_args);
+    grpc_channel_args_destroy(exec_ctx, new_args);
   }
   return true;
 }
@@ -81,6 +85,7 @@ void grpc_client_channel_init(void) {
                                    set_default_host_if_unset, NULL);
   grpc_channel_init_register_stage(GRPC_CLIENT_CHANNEL, INT_MAX, append_filter,
                                    (void *)&grpc_client_channel_filter);
+  grpc_http_connect_register_handshaker_factory();
 }
 
 void grpc_client_channel_shutdown(void) {
diff --git a/src/core/ext/client_channel/http_connect_handshaker.c b/src/core/ext/client_channel/http_connect_handshaker.c
index a0fc95e7bb..fba32561ac 100644
--- a/src/core/ext/client_channel/http_connect_handshaker.c
+++ b/src/core/ext/client_channel/http_connect_handshaker.c
@@ -44,8 +44,10 @@
 #include "src/core/ext/client_channel/resolver_registry.h"
 #include "src/core/ext/client_channel/uri_parser.h"
 #include "src/core/lib/channel/channel_args.h"
+#include "src/core/lib/channel/handshaker_registry.h"
 #include "src/core/lib/http/format_request.h"
 #include "src/core/lib/http/parser.h"
+#include "src/core/lib/slice/slice_internal.h"
 #include "src/core/lib/support/env.h"
 
 typedef struct http_connect_handshaker {
@@ -53,6 +55,8 @@ typedef struct http_connect_handshaker {
   grpc_handshaker base;
 
   char* proxy_server;
+  grpc_http_header* headers;
+  size_t num_headers;
 
   gpr_refcount refcount;
   gpr_mu mu;
@@ -83,11 +87,17 @@ static void http_connect_handshaker_unref(grpc_exec_ctx* exec_ctx,
       grpc_endpoint_destroy(exec_ctx, handshaker->endpoint_to_destroy);
     }
     if (handshaker->read_buffer_to_destroy != NULL) {
-      grpc_slice_buffer_destroy(handshaker->read_buffer_to_destroy);
+      grpc_slice_buffer_destroy_internal(exec_ctx,
+                                         handshaker->read_buffer_to_destroy);
       gpr_free(handshaker->read_buffer_to_destroy);
     }
     gpr_free(handshaker->proxy_server);
-    grpc_slice_buffer_destroy(&handshaker->write_buffer);
+    for (size_t i = 0; i < handshaker->num_headers; ++i) {
+      gpr_free(handshaker->headers[i].key);
+      gpr_free(handshaker->headers[i].value);
+    }
+    gpr_free(handshaker->headers);
+    grpc_slice_buffer_destroy_internal(exec_ctx, &handshaker->write_buffer);
     grpc_http_parser_destroy(&handshaker->http_parser);
     grpc_http_response_destroy(&handshaker->http_response);
     gpr_free(handshaker);
@@ -97,12 +107,12 @@ static void http_connect_handshaker_unref(grpc_exec_ctx* exec_ctx,
 // Set args fields to NULL, saving the endpoint and read buffer for
 // later destruction.
 static void cleanup_args_for_failure_locked(
-    http_connect_handshaker* handshaker) {
+    grpc_exec_ctx* exec_ctx, http_connect_handshaker* handshaker) {
   handshaker->endpoint_to_destroy = handshaker->args->endpoint;
   handshaker->args->endpoint = NULL;
   handshaker->read_buffer_to_destroy = handshaker->args->read_buffer;
   handshaker->args->read_buffer = NULL;
-  grpc_channel_args_destroy(handshaker->args->args);
+  grpc_channel_args_destroy(exec_ctx, handshaker->args->args);
   handshaker->args->args = NULL;
 }
 
@@ -125,7 +135,7 @@ static void handshake_failed_locked(grpc_exec_ctx* exec_ctx,
     grpc_endpoint_shutdown(exec_ctx, handshaker->args->endpoint);
     // Not shutting down, so the handshake failed.  Clean up before
     // invoking the callback.
-    cleanup_args_for_failure_locked(handshaker);
+    cleanup_args_for_failure_locked(exec_ctx, handshaker);
     // Set shutdown to true so that subsequent calls to
     // http_connect_handshaker_shutdown() do nothing.
     handshaker->shutdown = true;
@@ -193,7 +203,7 @@ static void on_read_done(grpc_exec_ctx* exec_ctx, void* arg,
                                &handshaker->args->read_buffer->slices[i + 1],
                                handshaker->args->read_buffer->count - i - 1);
         grpc_slice_buffer_swap(handshaker->args->read_buffer, &tmp_buffer);
-        grpc_slice_buffer_destroy(&tmp_buffer);
+        grpc_slice_buffer_destroy_internal(exec_ctx, &tmp_buffer);
         break;
       }
     }
@@ -210,7 +220,8 @@ static void on_read_done(grpc_exec_ctx* exec_ctx, void* arg,
   // complete (e.g., handling chunked transfer encoding or looking
   // at the Content-Length: header).
   if (handshaker->http_parser.state != GRPC_HTTP_BODY) {
-    grpc_slice_buffer_reset_and_unref(handshaker->args->read_buffer);
+    grpc_slice_buffer_reset_and_unref_internal(exec_ctx,
+                                               handshaker->args->read_buffer);
     grpc_endpoint_read(exec_ctx, handshaker->args->endpoint,
                        handshaker->args->read_buffer,
                        &handshaker->response_read_closure);
@@ -255,7 +266,7 @@ static void http_connect_handshaker_shutdown(grpc_exec_ctx* exec_ctx,
   if (!handshaker->shutdown) {
     handshaker->shutdown = true;
     grpc_endpoint_shutdown(exec_ctx, handshaker->args->endpoint);
-    cleanup_args_for_failure_locked(handshaker);
+    cleanup_args_for_failure_locked(exec_ctx, handshaker);
   }
   gpr_mu_unlock(&handshaker->mu);
 }
@@ -286,6 +297,8 @@ static void http_connect_handshaker_do_handshake(
   request.host = server_name;
   request.http.method = "CONNECT";
   request.http.path = server_name;
+  request.http.hdrs = handshaker->headers;
+  request.http.hdr_count = handshaker->num_headers;
   request.handshaker = &grpc_httpcli_plaintext;
   grpc_slice request_slice = grpc_httpcli_format_connect_request(&request);
   grpc_slice_buffer_add(&handshaker->write_buffer, request_slice);
@@ -303,7 +316,9 @@ static const grpc_handshaker_vtable http_connect_handshaker_vtable = {
     http_connect_handshaker_destroy, http_connect_handshaker_shutdown,
     http_connect_handshaker_do_handshake};
 
-grpc_handshaker* grpc_http_connect_handshaker_create(const char* proxy_server) {
+grpc_handshaker* grpc_http_connect_handshaker_create(const char* proxy_server,
+                                                     grpc_http_header* headers,
+                                                     size_t num_headers) {
   GPR_ASSERT(proxy_server != NULL);
   http_connect_handshaker* handshaker = gpr_malloc(sizeof(*handshaker));
   memset(handshaker, 0, sizeof(*handshaker));
@@ -311,6 +326,14 @@ grpc_handshaker* grpc_http_connect_handshaker_create(const char* proxy_server) {
   gpr_mu_init(&handshaker->mu);
   gpr_ref_init(&handshaker->refcount, 1);
   handshaker->proxy_server = gpr_strdup(proxy_server);
+  if (num_headers > 0) {
+    handshaker->headers = gpr_malloc(sizeof(grpc_http_header) * num_headers);
+    for (size_t i = 0; i < num_headers; ++i) {
+      handshaker->headers[i].key = gpr_strdup(headers[i].key);
+      handshaker->headers[i].value = gpr_strdup(headers[i].value);
+    }
+    handshaker->num_headers = num_headers;
+  }
   grpc_slice_buffer_init(&handshaker->write_buffer);
   grpc_closure_init(&handshaker->request_done_closure, on_write_done,
                     handshaker, grpc_schedule_on_exec_ctx);
@@ -344,3 +367,33 @@ done:
   grpc_uri_destroy(uri);
   return proxy_name;
 }
+
+//
+// handshaker factory
+//
+
+static void handshaker_factory_add_handshakers(
+    grpc_exec_ctx* exec_ctx, grpc_handshaker_factory* factory,
+    const grpc_channel_args* args, grpc_handshake_manager* handshake_mgr) {
+  char* proxy_name = grpc_get_http_proxy_server();
+  if (proxy_name != NULL) {
+    grpc_handshake_manager_add(
+        handshake_mgr,
+        grpc_http_connect_handshaker_create(proxy_name, NULL, 0));
+    gpr_free(proxy_name);
+  }
+}
+
+static void handshaker_factory_destroy(grpc_exec_ctx* exec_ctx,
+                                       grpc_handshaker_factory* factory) {}
+
+static const grpc_handshaker_factory_vtable handshaker_factory_vtable = {
+    handshaker_factory_add_handshakers, handshaker_factory_destroy};
+
+static grpc_handshaker_factory handshaker_factory = {
+    &handshaker_factory_vtable};
+
+void grpc_http_connect_register_handshaker_factory() {
+  grpc_handshaker_factory_register(true /* at_start */, HANDSHAKER_CLIENT,
+                                   &handshaker_factory);
+}
diff --git a/src/core/ext/client_channel/http_connect_handshaker.h b/src/core/ext/client_channel/http_connect_handshaker.h
index ea293852e6..c2e68de716 100644
--- a/src/core/ext/client_channel/http_connect_handshaker.h
+++ b/src/core/ext/client_channel/http_connect_handshaker.h
@@ -35,12 +35,18 @@
 #define GRPC_CORE_EXT_CLIENT_CHANNEL_HTTP_CONNECT_HANDSHAKER_H
 
 #include "src/core/lib/channel/handshaker.h"
+#include "src/core/lib/http/parser.h"
 
-/// Does NOT take ownership of \a proxy_server.
-grpc_handshaker* grpc_http_connect_handshaker_create(const char* proxy_server);
+/// Creates a new HTTP CONNECT handshaker.
+grpc_handshaker* grpc_http_connect_handshaker_create(const char* proxy_server,
+                                                     grpc_http_header* headers,
+                                                     size_t num_headers);
 
 /// Returns the name of the proxy to use, or NULL if no proxy is configured.
 /// Caller takes ownership of result.
 char* grpc_get_http_proxy_server();
 
+/// Registers handshaker factory.
+void grpc_http_connect_register_handshaker_factory();
+
 #endif /* GRPC_CORE_EXT_CLIENT_CHANNEL_HTTP_CONNECT_HANDSHAKER_H */
diff --git a/src/core/ext/client_channel/lb_policy_factory.c b/src/core/ext/client_channel/lb_policy_factory.c
index 8a474c8818..7af9bb0411 100644
--- a/src/core/ext/client_channel/lb_policy_factory.c
+++ b/src/core/ext/client_channel/lb_policy_factory.c
@@ -112,11 +112,13 @@ int grpc_lb_addresses_cmp(const grpc_lb_addresses* addresses1,
   return 0;
 }
 
-void grpc_lb_addresses_destroy(grpc_lb_addresses* addresses) {
+void grpc_lb_addresses_destroy(grpc_exec_ctx* exec_ctx,
+                               grpc_lb_addresses* addresses) {
   for (size_t i = 0; i < addresses->num_addresses; ++i) {
     gpr_free(addresses->addresses[i].balancer_name);
     if (addresses->addresses[i].user_data != NULL) {
-      addresses->user_data_vtable->destroy(addresses->addresses[i].user_data);
+      addresses->user_data_vtable->destroy(exec_ctx,
+                                           addresses->addresses[i].user_data);
     }
   }
   gpr_free(addresses->addresses);
@@ -126,8 +128,8 @@ void grpc_lb_addresses_destroy(grpc_lb_addresses* addresses) {
 static void* lb_addresses_copy(void* addresses) {
   return grpc_lb_addresses_copy(addresses);
 }
-static void lb_addresses_destroy(void* addresses) {
-  grpc_lb_addresses_destroy(addresses);
+static void lb_addresses_destroy(grpc_exec_ctx* exec_ctx, void* addresses) {
+  grpc_lb_addresses_destroy(exec_ctx, addresses);
 }
 static int lb_addresses_cmp(void* addresses1, void* addresses2) {
   return grpc_lb_addresses_cmp(addresses1, addresses2);
diff --git a/src/core/ext/client_channel/lb_policy_factory.h b/src/core/ext/client_channel/lb_policy_factory.h
index 79b3dee259..9b8b03f982 100644
--- a/src/core/ext/client_channel/lb_policy_factory.h
+++ b/src/core/ext/client_channel/lb_policy_factory.h
@@ -64,7 +64,7 @@ typedef struct grpc_lb_address {
 
 typedef struct grpc_lb_user_data_vtable {
   void *(*copy)(void *);
-  void (*destroy)(void *);
+  void (*destroy)(grpc_exec_ctx *exec_ctx, void *);
   int (*cmp)(void *, void *);
 } grpc_lb_user_data_vtable;
 
@@ -96,7 +96,8 @@ int grpc_lb_addresses_cmp(const grpc_lb_addresses *addresses1,
                           const grpc_lb_addresses *addresses2);
 
 /** Destroys \a addresses. */
-void grpc_lb_addresses_destroy(grpc_lb_addresses *addresses);
+void grpc_lb_addresses_destroy(grpc_exec_ctx *exec_ctx,
+                               grpc_lb_addresses *addresses);
 
 /** Returns a channel arg containing \a addresses. */
 grpc_arg grpc_lb_addresses_create_channel_arg(
diff --git a/src/core/ext/client_channel/subchannel.c b/src/core/ext/client_channel/subchannel.c
index 87f0ef298a..1bac82b451 100644
--- a/src/core/ext/client_channel/subchannel.c
+++ b/src/core/ext/client_channel/subchannel.c
@@ -46,6 +46,7 @@
 #include "src/core/lib/channel/connected_channel.h"
 #include "src/core/lib/iomgr/timer.h"
 #include "src/core/lib/profiling/timers.h"
+#include "src/core/lib/slice/slice_internal.h"
 #include "src/core/lib/support/backoff.h"
 #include "src/core/lib/surface/channel.h"
 #include "src/core/lib/surface/channel_init.h"
@@ -108,6 +109,9 @@ struct grpc_subchannel {
   /** callback for connection finishing */
   grpc_closure connected;
 
+  /** callback for our alarm */
+  grpc_closure on_alarm;
+
   /** pollset_set tracking who's interested in a connection
       being setup */
   grpc_pollset_set *pollset_set;
@@ -206,9 +210,9 @@ static void subchannel_destroy(grpc_exec_ctx *exec_ctx, void *arg,
                                grpc_error *error) {
   grpc_subchannel *c = arg;
   gpr_free((void *)c->filters);
-  grpc_channel_args_destroy(c->args);
+  grpc_channel_args_destroy(exec_ctx, c->args);
   gpr_free(c->addr);
-  grpc_slice_unref(c->initial_connect_string);
+  grpc_slice_unref_internal(exec_ctx, c->initial_connect_string);
   grpc_connectivity_state_destroy(exec_ctx, &c->state_tracker);
   grpc_connector_unref(exec_ctx, c->connector);
   grpc_pollset_set_destroy(c->pollset_set);
@@ -482,7 +486,8 @@ static void maybe_start_connecting_locked(grpc_exec_ctx *exec_ctx,
       gpr_log(GPR_INFO, "Retry in %" PRId64 ".%09d seconds",
               time_til_next.tv_sec, time_til_next.tv_nsec);
     }
-    grpc_timer_init(exec_ctx, &c->alarm, c->next_attempt, on_alarm, c, now);
+    grpc_closure_init(&c->on_alarm, on_alarm, c, grpc_schedule_on_exec_ctx);
+    grpc_timer_init(exec_ctx, &c->alarm, c->next_attempt, &c->on_alarm, now);
   }
 }
 
@@ -603,13 +608,13 @@ static void publish_transport_locked(grpc_exec_ctx *exec_ctx,
   /* construct channel stack */
   grpc_channel_stack_builder *builder = grpc_channel_stack_builder_create();
   grpc_channel_stack_builder_set_channel_arguments(
-      builder, c->connecting_result.channel_args);
+      exec_ctx, builder, c->connecting_result.channel_args);
   grpc_channel_stack_builder_set_transport(builder,
                                            c->connecting_result.transport);
 
   if (!grpc_channel_init_create_stack(exec_ctx, builder,
                                       GRPC_CLIENT_SUBCHANNEL)) {
-    grpc_channel_stack_builder_destroy(builder);
+    grpc_channel_stack_builder_destroy(exec_ctx, builder);
     abort(); /* TODO(ctiller): what to do here (previously we just crashed) */
   }
   grpc_error *error = grpc_channel_stack_builder_finish(
@@ -689,7 +694,7 @@ static void subchannel_connected(grpc_exec_ctx *exec_ctx, void *arg,
   }
   gpr_mu_unlock(&c->mu);
   GRPC_SUBCHANNEL_WEAK_UNREF(exec_ctx, c, "connected");
-  grpc_channel_args_destroy(delete_channel_args);
+  grpc_channel_args_destroy(exec_ctx, delete_channel_args);
 }
 
 /*
diff --git a/src/core/ext/client_channel/subchannel_index.c b/src/core/ext/client_channel/subchannel_index.c
index a1ba5e945c..1ebe03ef11 100644
--- a/src/core/ext/client_channel/subchannel_index.c
+++ b/src/core/ext/client_channel/subchannel_index.c
@@ -128,7 +128,7 @@ void grpc_subchannel_key_destroy(grpc_exec_ctx *exec_ctx,
                                  grpc_subchannel_key *k) {
   grpc_connector_unref(exec_ctx, k->connector);
   gpr_free((grpc_channel_args *)k->args.filters);
-  grpc_channel_args_destroy((grpc_channel_args *)k->args.args);
+  grpc_channel_args_destroy(exec_ctx, (grpc_channel_args *)k->args.args);
   gpr_free(k->args.addr);
   gpr_free(k);
 }
diff --git a/src/core/ext/client_channel/uri_parser.c b/src/core/ext/client_channel/uri_parser.c
index 0fbc542ef8..f8c946b275 100644
--- a/src/core/ext/client_channel/uri_parser.c
+++ b/src/core/ext/client_channel/uri_parser.c
@@ -42,7 +42,6 @@
 #include <grpc/support/port_platform.h>
 #include <grpc/support/string_util.h>
 
-#include "src/core/lib/slice/slice_string_helpers.h"
 #include "src/core/lib/support/string.h"
 
 /** a size_t default value... maps to all 1's */
@@ -138,7 +137,6 @@ static int parse_fragment_or_query(const char *uri_text, size_t *i) {
   return 1;
 }
 
-static void do_nothing(void *ignored) {}
 static void parse_query_parts(grpc_uri *uri) {
   static const char *QUERY_PARTS_SEPARATOR = "&";
   static const char *QUERY_PARTS_VALUE_SEPARATOR = "=";
@@ -149,38 +147,32 @@ static void parse_query_parts(grpc_uri *uri) {
     uri->num_query_parts = 0;
     return;
   }
-  grpc_slice query_slice =
-      grpc_slice_new(uri->query, strlen(uri->query), do_nothing);
-  grpc_slice_buffer query_parts; /* the &-separated elements of the query */
-  grpc_slice_buffer query_param_parts; /* the =-separated subelements */
 
-  grpc_slice_buffer_init(&query_parts);
-  grpc_slice_buffer_init(&query_param_parts);
-
-  grpc_slice_split(query_slice, QUERY_PARTS_SEPARATOR, &query_parts);
-  uri->query_parts = gpr_malloc(query_parts.count * sizeof(char *));
-  uri->query_parts_values = gpr_malloc(query_parts.count * sizeof(char *));
-  uri->num_query_parts = query_parts.count;
-  for (size_t i = 0; i < query_parts.count; i++) {
-    grpc_slice_split(query_parts.slices[i], QUERY_PARTS_VALUE_SEPARATOR,
-                     &query_param_parts);
-    GPR_ASSERT(query_param_parts.count > 0);
-    uri->query_parts[i] =
-        grpc_dump_slice(query_param_parts.slices[0], GPR_DUMP_ASCII);
-    if (query_param_parts.count > 1) {
+  gpr_string_split(uri->query, QUERY_PARTS_SEPARATOR, &uri->query_parts,
+                   &uri->num_query_parts);
+  uri->query_parts_values = gpr_malloc(uri->num_query_parts * sizeof(char **));
+  for (size_t i = 0; i < uri->num_query_parts; i++) {
+    char **query_param_parts;
+    size_t num_query_param_parts;
+    char *full = uri->query_parts[i];
+    gpr_string_split(full, QUERY_PARTS_VALUE_SEPARATOR, &query_param_parts,
+                     &num_query_param_parts);
+    GPR_ASSERT(num_query_param_parts > 0);
+    uri->query_parts[i] = query_param_parts[0];
+    if (num_query_param_parts > 1) {
       /* TODO(dgq): only the first value after the separator is considered.
        * Perhaps all chars after the first separator for the query part should
        * be included, even if they include the separator. */
-      uri->query_parts_values[i] =
-          grpc_dump_slice(query_param_parts.slices[1], GPR_DUMP_ASCII);
+      uri->query_parts_values[i] = query_param_parts[1];
     } else {
       uri->query_parts_values[i] = NULL;
     }
-    grpc_slice_buffer_reset_and_unref(&query_param_parts);
+    for (size_t j = 2; j < num_query_param_parts; j++) {
+      gpr_free(query_param_parts[j]);
+    }
+    gpr_free(query_param_parts);
+    gpr_free(full);
   }
-  grpc_slice_buffer_destroy(&query_parts);
-  grpc_slice_buffer_destroy(&query_param_parts);
-  grpc_slice_unref(query_slice);
 }
 
 grpc_uri *grpc_uri_parse(const char *uri_text, int suppress_errors) {
diff --git a/src/core/ext/lb_policy/grpclb/grpclb.c b/src/core/ext/lb_policy/grpclb/grpclb.c
index bb0ee9d95c..97f98df03a 100644
--- a/src/core/ext/lb_policy/grpclb/grpclb.c
+++ b/src/core/ext/lb_policy/grpclb/grpclb.c
@@ -117,6 +117,7 @@
 #include "src/core/lib/iomgr/sockaddr.h"
 #include "src/core/lib/iomgr/sockaddr_utils.h"
 #include "src/core/lib/iomgr/timer.h"
+#include "src/core/lib/slice/slice_internal.h"
 #include "src/core/lib/slice/slice_string_helpers.h"
 #include "src/core/lib/support/backoff.h"
 #include "src/core/lib/support/string.h"
@@ -326,6 +327,9 @@ typedef struct glb_lb_policy {
   /* A response from the LB server has been received. Process it */
   grpc_closure lb_on_response_received;
 
+  /* LB call retry timer callback. */
+  grpc_closure lb_on_call_retry;
+
   grpc_call *lb_call; /* streaming call to the LB server, */
 
   grpc_metadata_array lb_initial_metadata_recv; /* initial MD from LB server */
@@ -386,8 +390,8 @@ static bool is_server_valid(const grpc_grpclb_server *server, size_t idx,
 static void *lb_token_copy(void *token) {
   return token == NULL ? NULL : GRPC_MDELEM_REF(token);
 }
-static void lb_token_destroy(void *token) {
-  if (token != NULL) GRPC_MDELEM_UNREF(token);
+static void lb_token_destroy(grpc_exec_ctx *exec_ctx, void *token) {
+  if (token != NULL) GRPC_MDELEM_UNREF(exec_ctx, token);
 }
 static int lb_token_cmp(void *token1, void *token2) {
   if (token1 > token2) return 1;
@@ -421,7 +425,7 @@ static void parse_server(const grpc_grpclb_server *server,
 
 /* Returns addresses extracted from \a serverlist. */
 static grpc_lb_addresses *process_serverlist_locked(
-    const grpc_grpclb_serverlist *serverlist) {
+    grpc_exec_ctx *exec_ctx, const grpc_grpclb_serverlist *serverlist) {
   size_t num_valid = 0;
   /* first pass: count how many are valid in order to allocate the necessary
    * memory in a single block */
@@ -457,8 +461,8 @@ static grpc_lb_addresses *process_serverlist_locked(
           strnlen(server->load_balance_token, lb_token_max_length);
       grpc_mdstr *lb_token_mdstr = grpc_mdstr_from_buffer(
           (uint8_t *)server->load_balance_token, lb_token_length);
-      user_data = grpc_mdelem_from_metadata_strings(GRPC_MDSTR_LB_TOKEN,
-                                                    lb_token_mdstr);
+      user_data = grpc_mdelem_from_metadata_strings(
+          exec_ctx, GRPC_MDSTR_LB_TOKEN, lb_token_mdstr);
     } else {
       char *uri = grpc_sockaddr_to_uri(&addr);
       gpr_log(GPR_INFO,
@@ -581,7 +585,8 @@ static grpc_lb_policy *create_rr_locked(
   grpc_lb_policy_args args;
   memset(&args, 0, sizeof(args));
   args.client_channel_factory = glb_policy->cc_factory;
-  grpc_lb_addresses *addresses = process_serverlist_locked(serverlist);
+  grpc_lb_addresses *addresses =
+      process_serverlist_locked(exec_ctx, serverlist);
 
   // Replace the LB addresses in the channel args that we pass down to
   // the subchannel.
@@ -593,8 +598,8 @@ static grpc_lb_policy *create_rr_locked(
 
   grpc_lb_policy *rr = grpc_lb_policy_create(exec_ctx, "round_robin", &args);
   GPR_ASSERT(rr != NULL);
-  grpc_lb_addresses_destroy(addresses);
-  grpc_channel_args_destroy(args.args);
+  grpc_lb_addresses_destroy(exec_ctx, addresses);
+  grpc_channel_args_destroy(exec_ctx, args.args);
   return rr;
 }
 
@@ -840,7 +845,7 @@ static grpc_lb_policy *glb_create(grpc_exec_ctx *exec_ctx,
   glb_policy->lb_channel = grpc_client_channel_factory_create_channel(
       exec_ctx, glb_policy->cc_factory, target_uri_str,
       GRPC_CLIENT_CHANNEL_TYPE_LOAD_BALANCING, new_args);
-  grpc_channel_args_destroy(new_args);
+  grpc_channel_args_destroy(exec_ctx, new_args);
 
   gpr_free(target_uri_str);
   for (size_t i = 0; i < num_grpclb_addrs; i++) {
@@ -866,7 +871,7 @@ static void glb_destroy(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol) {
   GPR_ASSERT(glb_policy->pending_picks == NULL);
   GPR_ASSERT(glb_policy->pending_pings == NULL);
   gpr_free((void *)glb_policy->server_name);
-  grpc_channel_args_destroy(glb_policy->args);
+  grpc_channel_args_destroy(exec_ctx, glb_policy->args);
   grpc_channel_destroy(glb_policy->lb_channel);
   glb_policy->lb_channel = NULL;
   grpc_connectivity_state_destroy(exec_ctx, &glb_policy->state_tracker);
@@ -1089,7 +1094,8 @@ static void lb_on_server_status_received(grpc_exec_ctx *exec_ctx, void *arg,
                                          grpc_error *error);
 static void lb_on_response_received(grpc_exec_ctx *exec_ctx, void *arg,
                                     grpc_error *error);
-static void lb_call_init_locked(glb_lb_policy *glb_policy) {
+static void lb_call_init_locked(grpc_exec_ctx *exec_ctx,
+                                glb_lb_policy *glb_policy) {
   GPR_ASSERT(glb_policy->server_name != NULL);
   GPR_ASSERT(glb_policy->server_name[0] != '\0');
   GPR_ASSERT(!glb_policy->shutting_down);
@@ -1098,7 +1104,7 @@ static void lb_call_init_locked(glb_lb_policy *glb_policy) {
    * glb_policy->base.interested_parties, which is comprised of the polling
    * entities from \a client_channel. */
   glb_policy->lb_call = grpc_channel_create_pollset_set_call(
-      glb_policy->lb_channel, NULL, GRPC_PROPAGATE_DEFAULTS,
+      exec_ctx, glb_policy->lb_channel, NULL, GRPC_PROPAGATE_DEFAULTS,
       glb_policy->base.interested_parties,
       "/grpc.lb.v1.LoadBalancer/BalanceLoad", glb_policy->server_name,
       glb_policy->deadline, NULL);
@@ -1111,7 +1117,7 @@ static void lb_call_init_locked(glb_lb_policy *glb_policy) {
   grpc_slice request_payload_slice = grpc_grpclb_request_encode(request);
   glb_policy->lb_request_payload =
       grpc_raw_byte_buffer_create(&request_payload_slice, 1);
-  grpc_slice_unref(request_payload_slice);
+  grpc_slice_unref_internal(exec_ctx, request_payload_slice);
   grpc_grpclb_request_destroy(request);
 
   glb_policy->lb_call_status_details = NULL;
@@ -1152,7 +1158,7 @@ static void query_for_backends_locked(grpc_exec_ctx *exec_ctx,
   GPR_ASSERT(glb_policy->lb_channel != NULL);
   if (glb_policy->shutting_down) return;
 
-  lb_call_init_locked(glb_policy);
+  lb_call_init_locked(exec_ctx, glb_policy);
 
   if (grpc_lb_glb_trace) {
     gpr_log(GPR_INFO, "Query for backends (grpclb: %p, lb_call: %p)",
@@ -1237,7 +1243,7 @@ static void lb_on_response_received(grpc_exec_ctx *exec_ctx, void *arg,
         grpc_grpclb_response_parse_serverlist(response_slice);
     if (serverlist != NULL) {
       GPR_ASSERT(glb_policy->lb_call != NULL);
-      grpc_slice_unref(response_slice);
+      grpc_slice_unref_internal(exec_ctx, response_slice);
       if (grpc_lb_glb_trace) {
         gpr_log(GPR_INFO, "Serverlist with %lu servers received",
                 (unsigned long)serverlist->num_servers);
@@ -1281,7 +1287,7 @@ static void lb_on_response_received(grpc_exec_ctx *exec_ctx, void *arg,
     } else { /* serverlist == NULL */
       gpr_log(GPR_ERROR, "Invalid LB response received: '%s'. Ignoring.",
               grpc_dump_slice(response_slice, GPR_DUMP_ASCII | GPR_DUMP_HEX));
-      grpc_slice_unref(response_slice);
+      grpc_slice_unref_internal(exec_ctx, response_slice);
     }
 
     if (!glb_policy->shutting_down) {
@@ -1361,8 +1367,10 @@ static void lb_on_server_status_received(grpc_exec_ctx *exec_ctx, void *arg,
       }
     }
     GRPC_LB_POLICY_WEAK_REF(&glb_policy->base, "grpclb_retry_timer");
+    grpc_closure_init(&glb_policy->lb_on_call_retry, lb_call_on_retry_timer,
+                      glb_policy, grpc_schedule_on_exec_ctx);
     grpc_timer_init(exec_ctx, &glb_policy->lb_call_retry_timer, next_try,
-                    lb_call_on_retry_timer, glb_policy, now);
+                    &glb_policy->lb_on_call_retry, now);
   }
   gpr_mu_unlock(&glb_policy->mu);
   GRPC_LB_POLICY_WEAK_UNREF(exec_ctx, &glb_policy->base,
diff --git a/src/core/ext/lb_policy/grpclb/proto/grpc/lb/v1/load_balancer.pb.c b/src/core/ext/lb_policy/grpclb/proto/grpc/lb/v1/load_balancer.pb.c
index afecb716fb..e352e0396f 100644
--- a/src/core/ext/lb_policy/grpclb/proto/grpc/lb/v1/load_balancer.pb.c
+++ b/src/core/ext/lb_policy/grpclb/proto/grpc/lb/v1/load_balancer.pb.c
@@ -1,35 +1,3 @@
-/*
- *
- * Copyright 2016, Google Inc.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
- *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- *
- */
 /* Automatically generated nanopb constant definitions */
 /* Generated by nanopb-0.3.7-dev */
 
diff --git a/src/core/ext/lb_policy/grpclb/proto/grpc/lb/v1/load_balancer.pb.h b/src/core/ext/lb_policy/grpclb/proto/grpc/lb/v1/load_balancer.pb.h
index e36d0966f8..725aa7e386 100644
--- a/src/core/ext/lb_policy/grpclb/proto/grpc/lb/v1/load_balancer.pb.h
+++ b/src/core/ext/lb_policy/grpclb/proto/grpc/lb/v1/load_balancer.pb.h
@@ -1,35 +1,3 @@
-/*
- *
- * Copyright 2016, Google Inc.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
- *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- *
- */
 /* Automatically generated nanopb header */
 /* Generated by nanopb-0.3.7-dev */
 
diff --git a/src/core/ext/lb_policy/round_robin/round_robin.c b/src/core/ext/lb_policy/round_robin/round_robin.c
index 47f20a1904..cb679489c3 100644
--- a/src/core/ext/lb_policy/round_robin/round_robin.c
+++ b/src/core/ext/lb_policy/round_robin/round_robin.c
@@ -284,7 +284,7 @@ static void rr_destroy(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol) {
     GRPC_SUBCHANNEL_UNREF(exec_ctx, sd->subchannel, "rr_destroy");
     if (sd->user_data != NULL) {
       GPR_ASSERT(sd->user_data_vtable != NULL);
-      sd->user_data_vtable->destroy(sd->user_data);
+      sd->user_data_vtable->destroy(exec_ctx, sd->user_data);
     }
     gpr_free(sd);
   }
diff --git a/src/core/ext/load_reporting/load_reporting.c b/src/core/ext/load_reporting/load_reporting.c
index df1ea0ec9a..37b06a737f 100644
--- a/src/core/ext/load_reporting/load_reporting.c
+++ b/src/core/ext/load_reporting/load_reporting.c
@@ -53,7 +53,8 @@ static bool is_load_reporting_enabled(const grpc_channel_args *a) {
   return false;
 }
 
-static bool maybe_add_load_reporting_filter(grpc_channel_stack_builder *builder,
+static bool maybe_add_load_reporting_filter(grpc_exec_ctx *exec_ctx,
+                                            grpc_channel_stack_builder *builder,
                                             void *arg) {
   const grpc_channel_args *args =
       grpc_channel_stack_builder_get_channel_arguments(builder);
diff --git a/src/core/ext/load_reporting/load_reporting_filter.c b/src/core/ext/load_reporting/load_reporting_filter.c
index 1403eb0d33..07ef10e6a8 100644
--- a/src/core/ext/load_reporting/load_reporting_filter.c
+++ b/src/core/ext/load_reporting/load_reporting_filter.c
@@ -68,7 +68,8 @@ typedef struct {
   grpc_exec_ctx *exec_ctx;
 } recv_md_filter_args;
 
-static grpc_mdelem *recv_md_filter(void *user_data, grpc_mdelem *md) {
+static grpc_mdelem *recv_md_filter(grpc_exec_ctx *exec_ctx, void *user_data,
+                                   grpc_mdelem *md) {
   recv_md_filter_args *a = user_data;
   grpc_call_element *elem = a->elem;
   call_data *calld = elem->call_data;
@@ -92,8 +93,8 @@ static void on_initial_md_ready(grpc_exec_ctx *exec_ctx, void *user_data,
     recv_md_filter_args a;
     a.elem = elem;
     a.exec_ctx = exec_ctx;
-    grpc_metadata_batch_filter(calld->recv_initial_metadata, recv_md_filter,
-                               &a);
+    grpc_metadata_batch_filter(exec_ctx, calld->recv_initial_metadata,
+                               recv_md_filter, &a);
     if (calld->service_method == NULL) {
       err =
           grpc_error_add_child(err, GRPC_ERROR_CREATE("Missing :path header"));
@@ -192,7 +193,8 @@ static void destroy_channel_elem(grpc_exec_ctx *exec_ctx,
   */
 }
 
-static grpc_mdelem *lr_trailing_md_filter(void *user_data, grpc_mdelem *md) {
+static grpc_mdelem *lr_trailing_md_filter(grpc_exec_ctx *exec_ctx,
+                                          void *user_data, grpc_mdelem *md) {
   grpc_call_element *elem = user_data;
   call_data *calld = elem->call_data;
 
@@ -216,7 +218,7 @@ static void lr_start_transport_stream_op(grpc_exec_ctx *exec_ctx,
     calld->ops_recv_initial_metadata_ready = op->recv_initial_metadata_ready;
     op->recv_initial_metadata_ready = &calld->on_initial_md_ready;
   } else if (op->send_trailing_metadata) {
-    grpc_metadata_batch_filter(op->send_trailing_metadata,
+    grpc_metadata_batch_filter(exec_ctx, op->send_trailing_metadata,
                                lr_trailing_md_filter, elem);
   }
   grpc_call_next_op(exec_ctx, elem, op);
diff --git a/src/core/ext/resolver/README.md b/src/core/ext/resolver/README.md
new file mode 100644
index 0000000000..b0e234e96a
--- /dev/null
+++ b/src/core/ext/resolver/README.md
@@ -0,0 +1,4 @@
+# Resolver
+
+Implementations of various name resolution schemes.
+See the [naming spec](/doc/naming.md).
diff --git a/src/core/ext/resolver/dns/native/dns_resolver.c b/src/core/ext/resolver/dns/native/dns_resolver.c
index efbb2be4e1..655d9dc586 100644
--- a/src/core/ext/resolver/dns/native/dns_resolver.c
+++ b/src/core/ext/resolver/dns/native/dns_resolver.c
@@ -81,6 +81,7 @@ typedef struct {
   /** retry timer */
   bool have_retry_timer;
   grpc_timer retry_timer;
+  grpc_closure on_retry;
   /** retry backoff state */
   gpr_backoff backoff_state;
 
@@ -182,13 +183,13 @@ static void dns_on_resolved(grpc_exec_ctx *exec_ctx, void *arg,
     grpc_arg new_arg = grpc_lb_addresses_create_channel_arg(addresses);
     result = grpc_channel_args_copy_and_add(r->channel_args, &new_arg, 1);
     grpc_resolved_addresses_destroy(r->addresses);
-    grpc_lb_addresses_destroy(addresses);
+    grpc_lb_addresses_destroy(exec_ctx, addresses);
   } else {
     gpr_timespec now = gpr_now(GPR_CLOCK_MONOTONIC);
     gpr_timespec next_try = gpr_backoff_step(&r->backoff_state, now);
     gpr_timespec timeout = gpr_time_sub(next_try, now);
     const char *msg = grpc_error_string(error);
-    gpr_log(GPR_DEBUG, "dns resolution failed: %s", msg);
+    gpr_log(GPR_INFO, "dns resolution failed (will retry): %s", msg);
     grpc_error_free_string(msg);
     GPR_ASSERT(!r->have_retry_timer);
     r->have_retry_timer = true;
@@ -199,11 +200,12 @@ static void dns_on_resolved(grpc_exec_ctx *exec_ctx, void *arg,
     } else {
       gpr_log(GPR_DEBUG, "retrying immediately");
     }
-    grpc_timer_init(exec_ctx, &r->retry_timer, next_try, dns_on_retry_timer, r,
-                    now);
+    grpc_closure_init(&r->on_retry, dns_on_retry_timer, r,
+                      grpc_schedule_on_exec_ctx);
+    grpc_timer_init(exec_ctx, &r->retry_timer, next_try, &r->on_retry, now);
   }
   if (r->resolved_result != NULL) {
-    grpc_channel_args_destroy(r->resolved_result);
+    grpc_channel_args_destroy(exec_ctx, r->resolved_result);
   }
   r->resolved_result = result;
   r->resolved_version++;
@@ -242,12 +244,12 @@ static void dns_destroy(grpc_exec_ctx *exec_ctx, grpc_resolver *gr) {
   dns_resolver *r = (dns_resolver *)gr;
   gpr_mu_destroy(&r->mu);
   if (r->resolved_result != NULL) {
-    grpc_channel_args_destroy(r->resolved_result);
+    grpc_channel_args_destroy(exec_ctx, r->resolved_result);
   }
   grpc_pollset_set_destroy(r->interested_parties);
   gpr_free(r->name_to_resolve);
   gpr_free(r->default_port);
-  grpc_channel_args_destroy(r->channel_args);
+  grpc_channel_args_destroy(exec_ctx, r->channel_args);
   gpr_free(r);
 }
 
diff --git a/src/core/ext/resolver/sockaddr/sockaddr_resolver.c b/src/core/ext/resolver/sockaddr/sockaddr_resolver.c
index 55ea502c9e..c146a627cb 100644
--- a/src/core/ext/resolver/sockaddr/sockaddr_resolver.c
+++ b/src/core/ext/resolver/sockaddr/sockaddr_resolver.c
@@ -47,6 +47,7 @@
 #include "src/core/lib/channel/channel_args.h"
 #include "src/core/lib/iomgr/resolve_address.h"
 #include "src/core/lib/iomgr/unix_sockets_posix.h"
+#include "src/core/lib/slice/slice_internal.h"
 #include "src/core/lib/slice/slice_string_helpers.h"
 #include "src/core/lib/support/string.h"
 
@@ -131,8 +132,8 @@ static void sockaddr_maybe_finish_next_locked(grpc_exec_ctx *exec_ctx,
 static void sockaddr_destroy(grpc_exec_ctx *exec_ctx, grpc_resolver *gr) {
   sockaddr_resolver *r = (sockaddr_resolver *)gr;
   gpr_mu_destroy(&r->mu);
-  grpc_lb_addresses_destroy(r->addresses);
-  grpc_channel_args_destroy(r->channel_args);
+  grpc_lb_addresses_destroy(exec_ctx, r->addresses);
+  grpc_channel_args_destroy(exec_ctx, r->channel_args);
   gpr_free(r);
 }
 
@@ -161,7 +162,8 @@ char *unix_get_default_authority(grpc_resolver_factory *factory,
 
 static void do_nothing(void *ignored) {}
 
-static grpc_resolver *sockaddr_create(grpc_resolver_args *args,
+static grpc_resolver *sockaddr_create(grpc_exec_ctx *exec_ctx,
+                                      grpc_resolver_args *args,
                                       int parse(grpc_uri *uri,
                                                 grpc_resolved_address *dst)) {
   if (0 != strcmp(args->uri->authority, "")) {
@@ -188,10 +190,10 @@ static grpc_resolver *sockaddr_create(grpc_resolver_args *args,
     gpr_free(part_str);
     if (errors_found) break;
   }
-  grpc_slice_buffer_destroy(&path_parts);
-  grpc_slice_unref(path_slice);
+  grpc_slice_buffer_destroy_internal(exec_ctx, &path_parts);
+  grpc_slice_unref_internal(exec_ctx, path_slice);
   if (errors_found) {
-    grpc_lb_addresses_destroy(addresses);
+    grpc_lb_addresses_destroy(exec_ctx, addresses);
     return NULL;
   }
   /* Instantiate resolver. */
@@ -216,7 +218,7 @@ static void sockaddr_factory_unref(grpc_resolver_factory *factory) {}
   static grpc_resolver *name##_factory_create_resolver(                     \
       grpc_exec_ctx *exec_ctx, grpc_resolver_factory *factory,              \
       grpc_resolver_args *args) {                                           \
-    return sockaddr_create(args, parse_##name);                             \
+    return sockaddr_create(exec_ctx, args, parse_##name);                   \
   }                                                                         \
   static const grpc_resolver_factory_vtable name##_factory_vtable = {       \
       sockaddr_factory_ref, sockaddr_factory_unref,                         \
diff --git a/src/core/ext/transport/README.md b/src/core/ext/transport/README.md
new file mode 100644
index 0000000000..2290568784
--- /dev/null
+++ b/src/core/ext/transport/README.md
@@ -0,0 +1 @@
+Transports for gRPC
diff --git a/src/core/ext/transport/chttp2/README.md b/src/core/ext/transport/chttp2/README.md
new file mode 100644
index 0000000000..8880a47460
--- /dev/null
+++ b/src/core/ext/transport/chttp2/README.md
@@ -0,0 +1 @@
+CHTTP2 - gRPC's implementation of a HTTP2 based transport
diff --git a/src/core/ext/transport/chttp2/client/chttp2_connector.c b/src/core/ext/transport/chttp2/client/chttp2_connector.c
index c807342ebc..2c5dfaea60 100644
--- a/src/core/ext/transport/chttp2/client/chttp2_connector.c
+++ b/src/core/ext/transport/chttp2/client/chttp2_connector.c
@@ -46,8 +46,9 @@
 #include "src/core/ext/transport/chttp2/transport/chttp2_transport.h"
 #include "src/core/lib/channel/channel_args.h"
 #include "src/core/lib/channel/handshaker.h"
+#include "src/core/lib/channel/handshaker_registry.h"
 #include "src/core/lib/iomgr/tcp_client.h"
-#include "src/core/lib/security/transport/security_connector.h"
+#include "src/core/lib/slice/slice_internal.h"
 
 typedef struct {
   grpc_connector base;
@@ -58,9 +59,6 @@ typedef struct {
   bool shutdown;
   bool connecting;
 
-  grpc_chttp2_add_handshakers_func add_handshakers;
-  void *add_handshakers_user_data;
-
   grpc_closure *notify;
   grpc_connect_in_args args;
   grpc_connect_out_args *result;
@@ -124,8 +122,8 @@ static void on_handshake_done(grpc_exec_ctx *exec_ctx, void *arg,
       // point this can be removed.
       grpc_endpoint_shutdown(exec_ctx, args->endpoint);
       grpc_endpoint_destroy(exec_ctx, args->endpoint);
-      grpc_channel_args_destroy(args->args);
-      grpc_slice_buffer_destroy(args->read_buffer);
+      grpc_channel_args_destroy(exec_ctx, args->args);
+      grpc_slice_buffer_destroy_internal(exec_ctx, args->read_buffer);
       gpr_free(args->read_buffer);
     } else {
       error = GRPC_ERROR_REF(error);
@@ -151,16 +149,8 @@ static void on_handshake_done(grpc_exec_ctx *exec_ctx, void *arg,
 static void start_handshake_locked(grpc_exec_ctx *exec_ctx,
                                    chttp2_connector *c) {
   c->handshake_mgr = grpc_handshake_manager_create();
-  char *proxy_name = grpc_get_http_proxy_server();
-  if (proxy_name != NULL) {
-    grpc_handshake_manager_add(c->handshake_mgr,
-                               grpc_http_connect_handshaker_create(proxy_name));
-    gpr_free(proxy_name);
-  }
-  if (c->add_handshakers != NULL) {
-    c->add_handshakers(exec_ctx, c->add_handshakers_user_data,
+  grpc_handshakers_add(exec_ctx, HANDSHAKER_CLIENT, c->args.channel_args,
                        c->handshake_mgr);
-  }
   grpc_handshake_manager_do_handshake(
       exec_ctx, c->handshake_mgr, c->endpoint, c->args.channel_args,
       c->args.deadline, NULL /* acceptor */, on_handshake_done, c);
@@ -250,15 +240,11 @@ static const grpc_connector_vtable chttp2_connector_vtable = {
     chttp2_connector_ref, chttp2_connector_unref, chttp2_connector_shutdown,
     chttp2_connector_connect};
 
-grpc_connector *grpc_chttp2_connector_create(
-    grpc_exec_ctx *exec_ctx, grpc_chttp2_add_handshakers_func add_handshakers,
-    void *add_handshakers_user_data) {
+grpc_connector *grpc_chttp2_connector_create() {
   chttp2_connector *c = gpr_malloc(sizeof(*c));
   memset(c, 0, sizeof(*c));
   c->base.vtable = &chttp2_connector_vtable;
   gpr_mu_init(&c->mu);
   gpr_ref_init(&c->refs, 1);
-  c->add_handshakers = add_handshakers;
-  c->add_handshakers_user_data = add_handshakers_user_data;
   return &c->base;
 }
diff --git a/src/core/ext/transport/chttp2/client/chttp2_connector.h b/src/core/ext/transport/chttp2/client/chttp2_connector.h
index 58eba22417..f5d1025432 100644
--- a/src/core/ext/transport/chttp2/client/chttp2_connector.h
+++ b/src/core/ext/transport/chttp2/client/chttp2_connector.h
@@ -35,17 +35,7 @@
 #define GRPC_CORE_EXT_TRANSPORT_CHTTP2_CLIENT_CHTTP2_CONNECTOR_H
 
 #include "src/core/ext/client_channel/connector.h"
-#include "src/core/lib/channel/handshaker.h"
-#include "src/core/lib/iomgr/exec_ctx.h"
 
-typedef void (*grpc_chttp2_add_handshakers_func)(
-    grpc_exec_ctx* exec_ctx, void* user_data,
-    grpc_handshake_manager* handshake_mgr);
-
-/// If \a add_handshakers is non-NULL, it will be called with
-/// \a add_handshakers_user_data to add handshakers.
-grpc_connector* grpc_chttp2_connector_create(
-    grpc_exec_ctx* exec_ctx, grpc_chttp2_add_handshakers_func add_handshakers,
-    void* add_handshakers_user_data);
+grpc_connector* grpc_chttp2_connector_create();
 
 #endif /* GRPC_CORE_EXT_TRANSPORT_CHTTP2_CLIENT_CHTTP2_CONNECTOR_H */
diff --git a/src/core/ext/transport/chttp2/client/insecure/channel_create.c b/src/core/ext/transport/chttp2/client/insecure/channel_create.c
index a0d0652ce7..c9f4021216 100644
--- a/src/core/ext/transport/chttp2/client/insecure/channel_create.c
+++ b/src/core/ext/transport/chttp2/client/insecure/channel_create.c
@@ -53,8 +53,7 @@ static void client_channel_factory_unref(
 static grpc_subchannel *client_channel_factory_create_subchannel(
     grpc_exec_ctx *exec_ctx, grpc_client_channel_factory *cc_factory,
     const grpc_subchannel_args *args) {
-  grpc_connector *connector = grpc_chttp2_connector_create(
-      exec_ctx, NULL /* add_handshakers */, NULL /* user_data */);
+  grpc_connector *connector = grpc_chttp2_connector_create();
   grpc_subchannel *s = grpc_subchannel_create(exec_ctx, connector, args);
   grpc_connector_unref(exec_ctx, connector);
   return s;
@@ -72,7 +71,7 @@ static grpc_channel *client_channel_factory_create_channel(
   grpc_channel_args *new_args = grpc_channel_args_copy_and_add(args, &arg, 1);
   grpc_channel *channel = grpc_channel_create(exec_ctx, target, new_args,
                                               GRPC_CLIENT_CHANNEL, NULL);
-  grpc_channel_args_destroy(new_args);
+  grpc_channel_args_destroy(exec_ctx, new_args);
   return channel;
 }
 
@@ -96,17 +95,16 @@ grpc_channel *grpc_insecure_channel_create(const char *target,
       "grpc_insecure_channel_create(target=%p, args=%p, reserved=%p)", 3,
       (target, args, reserved));
   GPR_ASSERT(reserved == NULL);
-  grpc_client_channel_factory *factory =
-      (grpc_client_channel_factory *)&client_channel_factory;
   // Add channel arg containing the client channel factory.
-  grpc_arg arg = grpc_client_channel_factory_create_channel_arg(factory);
+  grpc_arg arg =
+      grpc_client_channel_factory_create_channel_arg(&client_channel_factory);
   grpc_channel_args *new_args = grpc_channel_args_copy_and_add(args, &arg, 1);
   // Create channel.
   grpc_channel *channel = client_channel_factory_create_channel(
-      &exec_ctx, factory, target, GRPC_CLIENT_CHANNEL_TYPE_REGULAR, new_args);
+      &exec_ctx, &client_channel_factory, target,
+      GRPC_CLIENT_CHANNEL_TYPE_REGULAR, new_args);
   // Clean up.
-  grpc_channel_args_destroy(new_args);
-  grpc_client_channel_factory_unref(&exec_ctx, factory);
+  grpc_channel_args_destroy(&exec_ctx, new_args);
   grpc_exec_ctx_finish(&exec_ctx);
   return channel != NULL ? channel : grpc_lame_client_channel_create(
                                          target, GRPC_STATUS_INTERNAL,
diff --git a/src/core/ext/transport/chttp2/client/insecure/channel_create_posix.c b/src/core/ext/transport/chttp2/client/insecure/channel_create_posix.c
index 1e5b1c22e3..f1069e2c57 100644
--- a/src/core/ext/transport/chttp2/client/insecure/channel_create_posix.c
+++ b/src/core/ext/transport/chttp2/client/insecure/channel_create_posix.c
@@ -74,7 +74,7 @@ grpc_channel *grpc_insecure_channel_create_from_fd(
   GPR_ASSERT(transport);
   grpc_channel *channel = grpc_channel_create(
       &exec_ctx, target, final_args, GRPC_CLIENT_DIRECT_CHANNEL, transport);
-  grpc_channel_args_destroy(final_args);
+  grpc_channel_args_destroy(&exec_ctx, final_args);
   grpc_chttp2_transport_start_reading(&exec_ctx, transport, NULL);
 
   grpc_exec_ctx_finish(&exec_ctx);
diff --git a/src/core/ext/transport/chttp2/client/secure/secure_channel_create.c b/src/core/ext/transport/chttp2/client/secure/secure_channel_create.c
index f35439cd44..f979d9bad5 100644
--- a/src/core/ext/transport/chttp2/client/secure/secure_channel_create.c
+++ b/src/core/ext/transport/chttp2/client/secure/secure_channel_create.c
@@ -46,40 +46,16 @@
 #include "src/core/lib/surface/api_trace.h"
 #include "src/core/lib/surface/channel.h"
 
-typedef struct {
-  grpc_client_channel_factory base;
-  gpr_refcount refs;
-  grpc_channel_security_connector *security_connector;
-} client_channel_factory;
-
 static void client_channel_factory_ref(
-    grpc_client_channel_factory *cc_factory) {
-  client_channel_factory *f = (client_channel_factory *)cc_factory;
-  gpr_ref(&f->refs);
-}
+    grpc_client_channel_factory *cc_factory) {}
 
 static void client_channel_factory_unref(
-    grpc_exec_ctx *exec_ctx, grpc_client_channel_factory *cc_factory) {
-  client_channel_factory *f = (client_channel_factory *)cc_factory;
-  if (gpr_unref(&f->refs)) {
-    GRPC_SECURITY_CONNECTOR_UNREF(&f->security_connector->base,
-                                  "client_channel_factory");
-    gpr_free(f);
-  }
-}
-
-static void add_handshakers(grpc_exec_ctx *exec_ctx, void *security_connector,
-                            grpc_handshake_manager *handshake_mgr) {
-  grpc_channel_security_connector_add_handshakers(exec_ctx, security_connector,
-                                                  handshake_mgr);
-}
+    grpc_exec_ctx *exec_ctx, grpc_client_channel_factory *cc_factory) {}
 
 static grpc_subchannel *client_channel_factory_create_subchannel(
     grpc_exec_ctx *exec_ctx, grpc_client_channel_factory *cc_factory,
     const grpc_subchannel_args *args) {
-  client_channel_factory *f = (client_channel_factory *)cc_factory;
-  grpc_connector *connector = grpc_chttp2_connector_create(
-      exec_ctx, add_handshakers, f->security_connector);
+  grpc_connector *connector = grpc_chttp2_connector_create();
   grpc_subchannel *s = grpc_subchannel_create(exec_ctx, connector, args);
   grpc_connector_unref(exec_ctx, connector);
   return s;
@@ -97,7 +73,7 @@ static grpc_channel *client_channel_factory_create_channel(
   grpc_channel_args *new_args = grpc_channel_args_copy_and_add(args, &arg, 1);
   grpc_channel *channel = grpc_channel_create(exec_ctx, target, new_args,
                                               GRPC_CLIENT_CHANNEL, NULL);
-  grpc_channel_args_destroy(new_args);
+  grpc_channel_args_destroy(exec_ctx, new_args);
   return channel;
 }
 
@@ -106,6 +82,9 @@ static const grpc_client_channel_factory_vtable client_channel_factory_vtable =
      client_channel_factory_create_subchannel,
      client_channel_factory_create_channel};
 
+static grpc_client_channel_factory client_channel_factory = {
+    &client_channel_factory_vtable};
+
 /* Create a secure client channel:
    Asynchronously: - resolve target
                    - connect to it (trying alternatives as presented)
@@ -132,39 +111,32 @@ grpc_channel *grpc_secure_channel_create(grpc_channel_credentials *creds,
   grpc_channel_security_connector *security_connector;
   grpc_channel_args *new_args_from_connector;
   if (grpc_channel_credentials_create_security_connector(
-          creds, target, args, &security_connector, &new_args_from_connector) !=
-      GRPC_SECURITY_OK) {
+          &exec_ctx, creds, target, args, &security_connector,
+          &new_args_from_connector) != GRPC_SECURITY_OK) {
     grpc_exec_ctx_finish(&exec_ctx);
     return grpc_lame_client_channel_create(
         target, GRPC_STATUS_INTERNAL, "Failed to create security connector.");
   }
-  // Create client channel factory.
-  client_channel_factory *f = gpr_malloc(sizeof(*f));
-  memset(f, 0, sizeof(*f));
-  f->base.vtable = &client_channel_factory_vtable;
-  gpr_ref_init(&f->refs, 1);
-  GRPC_SECURITY_CONNECTOR_REF(&security_connector->base,
-                              "grpc_secure_channel_create");
-  f->security_connector = security_connector;
   // Add channel args containing the client channel factory and security
   // connector.
-  grpc_arg new_args[2];
-  new_args[0] = grpc_client_channel_factory_create_channel_arg(&f->base);
-  new_args[1] = grpc_security_connector_to_arg(&security_connector->base);
-  grpc_channel_args *args_copy = grpc_channel_args_copy_and_add(
+  grpc_arg args_to_add[2];
+  args_to_add[0] =
+      grpc_client_channel_factory_create_channel_arg(&client_channel_factory);
+  args_to_add[1] = grpc_security_connector_to_arg(&security_connector->base);
+  grpc_channel_args *new_args = grpc_channel_args_copy_and_add(
       new_args_from_connector != NULL ? new_args_from_connector : args,
-      new_args, GPR_ARRAY_SIZE(new_args));
+      args_to_add, GPR_ARRAY_SIZE(args_to_add));
   if (new_args_from_connector != NULL) {
-    grpc_channel_args_destroy(new_args_from_connector);
+    grpc_channel_args_destroy(&exec_ctx, new_args_from_connector);
   }
   // Create channel.
   grpc_channel *channel = client_channel_factory_create_channel(
-      &exec_ctx, &f->base, target, GRPC_CLIENT_CHANNEL_TYPE_REGULAR, args_copy);
+      &exec_ctx, &client_channel_factory, target,
+      GRPC_CLIENT_CHANNEL_TYPE_REGULAR, new_args);
   // Clean up.
-  GRPC_SECURITY_CONNECTOR_UNREF(&f->security_connector->base,
+  GRPC_SECURITY_CONNECTOR_UNREF(&exec_ctx, &security_connector->base,
                                 "secure_client_channel_factory_create_channel");
-  grpc_channel_args_destroy(args_copy);
-  grpc_client_channel_factory_unref(&exec_ctx, &f->base);
+  grpc_channel_args_destroy(&exec_ctx, new_args);
   grpc_exec_ctx_finish(&exec_ctx);
   return channel; /* may be NULL */
 }
diff --git a/src/core/ext/transport/chttp2/server/chttp2_server.c b/src/core/ext/transport/chttp2/server/chttp2_server.c
index 9af62d372e..574d1a7710 100644
--- a/src/core/ext/transport/chttp2/server/chttp2_server.c
+++ b/src/core/ext/transport/chttp2/server/chttp2_server.c
@@ -46,31 +46,15 @@
 #include "src/core/ext/transport/chttp2/transport/chttp2_transport.h"
 #include "src/core/lib/channel/channel_args.h"
 #include "src/core/lib/channel/handshaker.h"
+#include "src/core/lib/channel/handshaker_registry.h"
 #include "src/core/lib/channel/http_server_filter.h"
 #include "src/core/lib/iomgr/endpoint.h"
 #include "src/core/lib/iomgr/resolve_address.h"
 #include "src/core/lib/iomgr/tcp_server.h"
+#include "src/core/lib/slice/slice_internal.h"
 #include "src/core/lib/surface/api_trace.h"
 #include "src/core/lib/surface/server.h"
 
-void grpc_chttp2_server_handshaker_factory_add_handshakers(
-    grpc_exec_ctx *exec_ctx,
-    grpc_chttp2_server_handshaker_factory *handshaker_factory,
-    grpc_handshake_manager *handshake_mgr) {
-  if (handshaker_factory != NULL) {
-    handshaker_factory->vtable->add_handshakers(exec_ctx, handshaker_factory,
-                                                handshake_mgr);
-  }
-}
-
-void grpc_chttp2_server_handshaker_factory_destroy(
-    grpc_exec_ctx *exec_ctx,
-    grpc_chttp2_server_handshaker_factory *handshaker_factory) {
-  if (handshaker_factory != NULL) {
-    handshaker_factory->vtable->destroy(exec_ctx, handshaker_factory);
-  }
-}
-
 typedef struct pending_handshake_manager_node {
   grpc_handshake_manager *handshake_mgr;
   struct pending_handshake_manager_node *next;
@@ -80,7 +64,6 @@ typedef struct {
   grpc_server *server;
   grpc_tcp_server *tcp_server;
   grpc_channel_args *args;
-  grpc_chttp2_server_handshaker_factory *handshaker_factory;
   gpr_mu mu;
   bool shutdown;
   grpc_closure tcp_server_shutdown_complete;
@@ -148,8 +131,8 @@ static void on_handshake_done(grpc_exec_ctx *exec_ctx, void *arg,
       // point this can be removed.
       grpc_endpoint_shutdown(exec_ctx, args->endpoint);
       grpc_endpoint_destroy(exec_ctx, args->endpoint);
-      grpc_channel_args_destroy(args->args);
-      grpc_slice_buffer_destroy(args->read_buffer);
+      grpc_channel_args_destroy(exec_ctx, args->args);
+      grpc_slice_buffer_destroy_internal(exec_ctx, args->read_buffer);
       gpr_free(args->read_buffer);
     }
   } else {
@@ -164,7 +147,7 @@ static void on_handshake_done(grpc_exec_ctx *exec_ctx, void *arg,
           connection_state->accepting_pollset, args->args);
       grpc_chttp2_transport_start_reading(exec_ctx, transport,
                                           args->read_buffer);
-      grpc_channel_args_destroy(args->args);
+      grpc_channel_args_destroy(exec_ctx, args->args);
     }
   }
   pending_handshake_manager_remove_locked(connection_state->server_state,
@@ -197,8 +180,8 @@ static void on_accept(grpc_exec_ctx *exec_ctx, void *arg, grpc_endpoint *tcp,
   connection_state->accepting_pollset = accepting_pollset;
   connection_state->acceptor = acceptor;
   connection_state->handshake_mgr = handshake_mgr;
-  grpc_chttp2_server_handshaker_factory_add_handshakers(
-      exec_ctx, state->handshaker_factory, connection_state->handshake_mgr);
+  grpc_handshakers_add(exec_ctx, HANDSHAKER_SERVER, state->args,
+                       connection_state->handshake_mgr);
   // TODO(roth): We should really get this timeout value from channel
   // args instead of hard-coding it.
   const gpr_timespec deadline = gpr_time_add(
@@ -232,13 +215,11 @@ static void tcp_server_shutdown_complete(grpc_exec_ctx *exec_ctx, void *arg,
   // Flush queued work before destroying handshaker factory, since that
   // may do a synchronous unref.
   grpc_exec_ctx_flush(exec_ctx);
-  grpc_chttp2_server_handshaker_factory_destroy(exec_ctx,
-                                                state->handshaker_factory);
   if (destroy_done != NULL) {
     destroy_done->cb(exec_ctx, destroy_done->cb_arg, GRPC_ERROR_REF(error));
     grpc_exec_ctx_flush(exec_ctx);
   }
-  grpc_channel_args_destroy(state->args);
+  grpc_channel_args_destroy(exec_ctx, state->args);
   gpr_mu_destroy(&state->mu);
   gpr_free(state);
 }
@@ -258,10 +239,10 @@ static void server_destroy_listener(grpc_exec_ctx *exec_ctx,
   grpc_tcp_server_unref(exec_ctx, tcp_server);
 }
 
-grpc_error *grpc_chttp2_server_add_port(
-    grpc_exec_ctx *exec_ctx, grpc_server *server, const char *addr,
-    grpc_channel_args *args,
-    grpc_chttp2_server_handshaker_factory *handshaker_factory, int *port_num) {
+grpc_error *grpc_chttp2_server_add_port(grpc_exec_ctx *exec_ctx,
+                                        grpc_server *server, const char *addr,
+                                        grpc_channel_args *args,
+                                        int *port_num) {
   grpc_resolved_addresses *resolved = NULL;
   grpc_tcp_server *tcp_server = NULL;
   size_t i;
@@ -292,7 +273,6 @@ grpc_error *grpc_chttp2_server_add_port(
   state->server = server;
   state->tcp_server = tcp_server;
   state->args = args;
-  state->handshaker_factory = handshaker_factory;
   state->shutdown = true;
   gpr_mu_init(&state->mu);
 
@@ -346,8 +326,7 @@ error:
   if (tcp_server) {
     grpc_tcp_server_unref(exec_ctx, tcp_server);
   } else {
-    grpc_channel_args_destroy(args);
-    grpc_chttp2_server_handshaker_factory_destroy(exec_ctx, handshaker_factory);
+    grpc_channel_args_destroy(exec_ctx, args);
     gpr_free(state);
   }
   *port_num = 0;
diff --git a/src/core/ext/transport/chttp2/server/chttp2_server.h b/src/core/ext/transport/chttp2/server/chttp2_server.h
index aa364b565d..2581ebaae9 100644
--- a/src/core/ext/transport/chttp2/server/chttp2_server.h
+++ b/src/core/ext/transport/chttp2/server/chttp2_server.h
@@ -36,43 +36,12 @@
 
 #include <grpc/impl/codegen/grpc_types.h>
 
-#include "src/core/lib/channel/handshaker.h"
 #include "src/core/lib/iomgr/exec_ctx.h"
 
-/// A server handshaker factory is used to create handshakers for server
-/// connections.
-typedef struct grpc_chttp2_server_handshaker_factory
-    grpc_chttp2_server_handshaker_factory;
-
-typedef struct {
-  void (*add_handshakers)(
-      grpc_exec_ctx *exec_ctx,
-      grpc_chttp2_server_handshaker_factory *handshaker_factory,
-      grpc_handshake_manager *handshake_mgr);
-  void (*destroy)(grpc_exec_ctx *exec_ctx,
-                  grpc_chttp2_server_handshaker_factory *handshaker_factory);
-} grpc_chttp2_server_handshaker_factory_vtable;
-
-struct grpc_chttp2_server_handshaker_factory {
-  const grpc_chttp2_server_handshaker_factory_vtable *vtable;
-};
-
-void grpc_chttp2_server_handshaker_factory_add_handshakers(
-    grpc_exec_ctx *exec_ctx,
-    grpc_chttp2_server_handshaker_factory *handshaker_factory,
-    grpc_handshake_manager *handshake_mgr);
-
-void grpc_chttp2_server_handshaker_factory_destroy(
-    grpc_exec_ctx *exec_ctx,
-    grpc_chttp2_server_handshaker_factory *handshaker_factory);
-
 /// Adds a port to \a server.  Sets \a port_num to the port number.
-/// If \a handshaker_factory is not NULL, it will be used to create
-/// handshakers for the port.
-/// Takes ownership of \a args and \a handshaker_factory.
-grpc_error *grpc_chttp2_server_add_port(
-    grpc_exec_ctx *exec_ctx, grpc_server *server, const char *addr,
-    grpc_channel_args *args,
-    grpc_chttp2_server_handshaker_factory *handshaker_factory, int *port_num);
+/// Takes ownership of \a args.
+grpc_error *grpc_chttp2_server_add_port(grpc_exec_ctx *exec_ctx,
+                                        grpc_server *server, const char *addr,
+                                        grpc_channel_args *args, int *port_num);
 
 #endif /* GRPC_CORE_EXT_TRANSPORT_CHTTP2_SERVER_CHTTP2_SERVER_H */
diff --git a/src/core/ext/transport/chttp2/server/insecure/server_chttp2.c b/src/core/ext/transport/chttp2/server/insecure/server_chttp2.c
index 7e286d4e46..bf5026bea6 100644
--- a/src/core/ext/transport/chttp2/server/insecure/server_chttp2.c
+++ b/src/core/ext/transport/chttp2/server/insecure/server_chttp2.c
@@ -47,8 +47,7 @@ int grpc_server_add_insecure_http2_port(grpc_server *server, const char *addr) {
                  (server, addr));
   grpc_error *err = grpc_chttp2_server_add_port(
       &exec_ctx, server, addr,
-      grpc_channel_args_copy(grpc_server_get_channel_args(server)),
-      NULL /* handshaker_factory */, &port_num);
+      grpc_channel_args_copy(grpc_server_get_channel_args(server)), &port_num);
   if (err != GRPC_ERROR_NONE) {
     const char *msg = grpc_error_string(err);
     gpr_log(GPR_ERROR, "%s", msg);
diff --git a/src/core/ext/transport/chttp2/server/insecure/server_chttp2_posix.c b/src/core/ext/transport/chttp2/server/insecure/server_chttp2_posix.c
index aa2ecf5743..f46e849932 100644
--- a/src/core/ext/transport/chttp2/server/insecure/server_chttp2_posix.c
+++ b/src/core/ext/transport/chttp2/server/insecure/server_chttp2_posix.c
@@ -62,7 +62,7 @@ void grpc_server_add_insecure_channel_from_fd(grpc_server *server,
   grpc_endpoint *server_endpoint =
       grpc_tcp_create(grpc_fd_create(fd, name), resource_quota,
                       GRPC_TCP_DEFAULT_READ_SLICE_SIZE, name);
-  grpc_resource_quota_internal_unref(&exec_ctx, resource_quota);
+  grpc_resource_quota_unref_internal(&exec_ctx, resource_quota);
 
   gpr_free(name);
 
diff --git a/src/core/ext/transport/chttp2/server/secure/server_secure_chttp2.c b/src/core/ext/transport/chttp2/server/secure/server_secure_chttp2.c
index a33a7a3f7d..395c79a71d 100644
--- a/src/core/ext/transport/chttp2/server/secure/server_secure_chttp2.c
+++ b/src/core/ext/transport/chttp2/server/secure/server_secure_chttp2.c
@@ -49,34 +49,6 @@
 #include "src/core/lib/surface/api_trace.h"
 #include "src/core/lib/surface/server.h"
 
-typedef struct {
-  grpc_chttp2_server_handshaker_factory base;
-  grpc_server_security_connector *security_connector;
-} server_security_handshaker_factory;
-
-static void server_security_handshaker_factory_add_handshakers(
-    grpc_exec_ctx *exec_ctx, grpc_chttp2_server_handshaker_factory *hf,
-    grpc_handshake_manager *handshake_mgr) {
-  server_security_handshaker_factory *handshaker_factory =
-      (server_security_handshaker_factory *)hf;
-  grpc_server_security_connector_add_handshakers(
-      exec_ctx, handshaker_factory->security_connector, handshake_mgr);
-}
-
-static void server_security_handshaker_factory_destroy(
-    grpc_exec_ctx *exec_ctx, grpc_chttp2_server_handshaker_factory *hf) {
-  server_security_handshaker_factory *handshaker_factory =
-      (server_security_handshaker_factory *)hf;
-  GRPC_SECURITY_CONNECTOR_UNREF(&handshaker_factory->security_connector->base,
-                                "server");
-  gpr_free(hf);
-}
-
-static const grpc_chttp2_server_handshaker_factory_vtable
-    server_security_handshaker_factory_vtable = {
-        server_security_handshaker_factory_add_handshakers,
-        server_security_handshaker_factory_destroy};
-
 int grpc_server_add_secure_http2_port(grpc_server *server, const char *addr,
                                       grpc_server_credentials *creds) {
   grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
@@ -94,7 +66,7 @@ int grpc_server_add_secure_http2_port(grpc_server *server, const char *addr,
     goto done;
   }
   grpc_security_status status =
-      grpc_server_credentials_create_security_connector(creds, &sc);
+      grpc_server_credentials_create_security_connector(&exec_ctx, creds, &sc);
   if (status != GRPC_SECURITY_OK) {
     char *msg;
     gpr_asprintf(&msg,
@@ -105,20 +77,19 @@ int grpc_server_add_secure_http2_port(grpc_server *server, const char *addr,
     gpr_free(msg);
     goto done;
   }
-  // Create handshaker factory.
-  server_security_handshaker_factory *handshaker_factory =
-      gpr_malloc(sizeof(*handshaker_factory));
-  memset(handshaker_factory, 0, sizeof(*handshaker_factory));
-  handshaker_factory->base.vtable = &server_security_handshaker_factory_vtable;
-  handshaker_factory->security_connector = sc;
   // Create channel args.
-  grpc_arg channel_arg = grpc_server_credentials_to_arg(creds);
-  grpc_channel_args *args = grpc_channel_args_copy_and_add(
-      grpc_server_get_channel_args(server), &channel_arg, 1);
+  grpc_arg args_to_add[2];
+  args_to_add[0] = grpc_server_credentials_to_arg(creds);
+  args_to_add[1] = grpc_security_connector_to_arg(&sc->base);
+  grpc_channel_args *args =
+      grpc_channel_args_copy_and_add(grpc_server_get_channel_args(server),
+                                     args_to_add, GPR_ARRAY_SIZE(args_to_add));
   // Add server port.
-  err = grpc_chttp2_server_add_port(&exec_ctx, server, addr, args,
-                                    &handshaker_factory->base, &port_num);
+  err = grpc_chttp2_server_add_port(&exec_ctx, server, addr, args, &port_num);
 done:
+  if (sc != NULL) {
+    GRPC_SECURITY_CONNECTOR_UNREF(&exec_ctx, &sc->base, "server");
+  }
   grpc_exec_ctx_finish(&exec_ctx);
   if (err != GRPC_ERROR_NONE) {
     const char *msg = grpc_error_string(err);
diff --git a/src/core/ext/transport/chttp2/transport/bin_decoder.c b/src/core/ext/transport/chttp2/transport/bin_decoder.c
index 3eef80b557..8db36e4a7f 100644
--- a/src/core/ext/transport/chttp2/transport/bin_decoder.c
+++ b/src/core/ext/transport/chttp2/transport/bin_decoder.c
@@ -34,6 +34,7 @@
 #include "src/core/ext/transport/chttp2/transport/bin_decoder.h"
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
+#include "src/core/lib/slice/slice_internal.h"
 #include "src/core/lib/slice/slice_string_helpers.h"
 #include "src/core/lib/support/string.h"
 
@@ -143,7 +144,8 @@ bool grpc_base64_decode_partial(struct grpc_base64_decode_context *ctx) {
   return true;
 }
 
-grpc_slice grpc_chttp2_base64_decode(grpc_slice input) {
+grpc_slice grpc_chttp2_base64_decode(grpc_exec_ctx *exec_ctx,
+                                     grpc_slice input) {
   size_t input_length = GRPC_SLICE_LENGTH(input);
   size_t output_length = input_length / 4 * 3;
   struct grpc_base64_decode_context ctx;
@@ -179,7 +181,7 @@ grpc_slice grpc_chttp2_base64_decode(grpc_slice input) {
     char *s = grpc_dump_slice(input, GPR_DUMP_ASCII);
     gpr_log(GPR_ERROR, "Base64 decoding failed, input string:\n%s\n", s);
     gpr_free(s);
-    grpc_slice_unref(output);
+    grpc_slice_unref_internal(exec_ctx, output);
     return gpr_empty_slice();
   }
   GPR_ASSERT(ctx.output_cur == GRPC_SLICE_END_PTR(output));
@@ -187,7 +189,8 @@ grpc_slice grpc_chttp2_base64_decode(grpc_slice input) {
   return output;
 }
 
-grpc_slice grpc_chttp2_base64_decode_with_length(grpc_slice input,
+grpc_slice grpc_chttp2_base64_decode_with_length(grpc_exec_ctx *exec_ctx,
+                                                 grpc_slice input,
                                                  size_t output_length) {
   size_t input_length = GRPC_SLICE_LENGTH(input);
   grpc_slice output = grpc_slice_malloc(output_length);
@@ -200,7 +203,7 @@ grpc_slice grpc_chttp2_base64_decode_with_length(grpc_slice input,
             "grpc_chttp2_base64_decode_with_length has a length of %d, which "
             "has a tail of 1 byte.\n",
             (int)input_length);
-    grpc_slice_unref(output);
+    grpc_slice_unref_internal(exec_ctx, output);
     return gpr_empty_slice();
   }
 
@@ -210,7 +213,7 @@ grpc_slice grpc_chttp2_base64_decode_with_length(grpc_slice input,
             "than the max possible output length %d.\n",
             (int)output_length,
             (int)(input_length / 4 * 3 + tail_xtra[input_length % 4]));
-    grpc_slice_unref(output);
+    grpc_slice_unref_internal(exec_ctx, output);
     return gpr_empty_slice();
   }
 
@@ -224,7 +227,7 @@ grpc_slice grpc_chttp2_base64_decode_with_length(grpc_slice input,
     char *s = grpc_dump_slice(input, GPR_DUMP_ASCII);
     gpr_log(GPR_ERROR, "Base64 decoding failed, input string:\n%s\n", s);
     gpr_free(s);
-    grpc_slice_unref(output);
+    grpc_slice_unref_internal(exec_ctx, output);
     return gpr_empty_slice();
   }
   GPR_ASSERT(ctx.output_cur == GRPC_SLICE_END_PTR(output));
diff --git a/src/core/ext/transport/chttp2/transport/bin_decoder.h b/src/core/ext/transport/chttp2/transport/bin_decoder.h
index 83a90be519..48ffb2ae3b 100644
--- a/src/core/ext/transport/chttp2/transport/bin_decoder.h
+++ b/src/core/ext/transport/chttp2/transport/bin_decoder.h
@@ -55,12 +55,13 @@ bool grpc_base64_decode_partial(struct grpc_base64_decode_context *ctx);
 
 /* base64 decode a slice with pad chars. Returns a new slice, does not take
    ownership of the input. Returns an empty slice if decoding is failed. */
-grpc_slice grpc_chttp2_base64_decode(grpc_slice input);
+grpc_slice grpc_chttp2_base64_decode(grpc_exec_ctx *exec_ctx, grpc_slice input);
 
 /* base64 decode a slice without pad chars, data length is needed. Returns a new
    slice, does not take ownership of the input. Returns an empty slice if
    decoding is failed. */
-grpc_slice grpc_chttp2_base64_decode_with_length(grpc_slice input,
+grpc_slice grpc_chttp2_base64_decode_with_length(grpc_exec_ctx *exec_ctx,
+                                                 grpc_slice input,
                                                  size_t output_length);
 
 #endif /* GRPC_CORE_EXT_TRANSPORT_CHTTP2_TRANSPORT_BIN_DECODER_H */
diff --git a/src/core/ext/transport/chttp2/transport/bin_encoder.h b/src/core/ext/transport/chttp2/transport/bin_encoder.h
index 9e143b46e2..477559d0e2 100644
--- a/src/core/ext/transport/chttp2/transport/bin_encoder.h
+++ b/src/core/ext/transport/chttp2/transport/bin_encoder.h
@@ -47,7 +47,7 @@ grpc_slice grpc_chttp2_huffman_compress(grpc_slice input);
 /* equivalent to:
    grpc_slice x = grpc_chttp2_base64_encode(input);
    grpc_slice y = grpc_chttp2_huffman_compress(x);
-   grpc_slice_unref(x);
+   grpc_slice_unref_internal(exec_ctx, x);
    return y; */
 grpc_slice grpc_chttp2_base64_encode_and_huffman_compress_impl(
     grpc_slice input);
diff --git a/src/core/ext/transport/chttp2/transport/chttp2_transport.c b/src/core/ext/transport/chttp2/transport/chttp2_transport.c
index 558d588b40..f297dd91a3 100644
--- a/src/core/ext/transport/chttp2/transport/chttp2_transport.c
+++ b/src/core/ext/transport/chttp2/transport/chttp2_transport.c
@@ -47,10 +47,12 @@
 #include "src/core/ext/transport/chttp2/transport/http2_errors.h"
 #include "src/core/ext/transport/chttp2/transport/internal.h"
 #include "src/core/ext/transport/chttp2/transport/status_conversion.h"
+#include "src/core/ext/transport/chttp2/transport/varint.h"
 #include "src/core/lib/channel/channel_args.h"
 #include "src/core/lib/http/parser.h"
 #include "src/core/lib/iomgr/workqueue.h"
 #include "src/core/lib/profiling/timers.h"
+#include "src/core/lib/slice/slice_internal.h"
 #include "src/core/lib/slice/slice_string_helpers.h"
 #include "src/core/lib/support/string.h"
 #include "src/core/lib/transport/static_metadata.h"
@@ -146,13 +148,13 @@ static void destruct_transport(grpc_exec_ctx *exec_ctx,
 
   grpc_endpoint_destroy(exec_ctx, t->ep);
 
-  grpc_slice_buffer_destroy(&t->qbuf);
+  grpc_slice_buffer_destroy_internal(exec_ctx, &t->qbuf);
 
-  grpc_slice_buffer_destroy(&t->outbuf);
-  grpc_chttp2_hpack_compressor_destroy(&t->hpack_compressor);
+  grpc_slice_buffer_destroy_internal(exec_ctx, &t->outbuf);
+  grpc_chttp2_hpack_compressor_destroy(exec_ctx, &t->hpack_compressor);
 
-  grpc_slice_buffer_destroy(&t->read_buffer);
-  grpc_chttp2_hpack_parser_destroy(&t->hpack_parser);
+  grpc_slice_buffer_destroy_internal(exec_ctx, &t->read_buffer);
+  grpc_chttp2_hpack_parser_destroy(exec_ctx, &t->hpack_parser);
   grpc_chttp2_goaway_parser_destroy(&t->goaway_parser);
 
   for (i = 0; i < STREAM_LIST_COUNT; i++) {
@@ -266,7 +268,7 @@ static void init_transport(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
                                  .integral_range = 10});
 
   grpc_chttp2_goaway_parser_init(&t->goaway_parser);
-  grpc_chttp2_hpack_parser_init(&t->hpack_parser);
+  grpc_chttp2_hpack_parser_init(exec_ctx, &t->hpack_parser);
 
   grpc_slice_buffer_init(&t->read_buffer);
 
@@ -544,9 +546,11 @@ static void destroy_stream_locked(grpc_exec_ctx *exec_ctx, void *sp,
   GPR_ASSERT(s->recv_message_ready == NULL);
   GPR_ASSERT(s->recv_trailing_metadata_finished == NULL);
   grpc_chttp2_data_parser_destroy(exec_ctx, &s->data_parser);
-  grpc_chttp2_incoming_metadata_buffer_destroy(&s->metadata_buffer[0]);
-  grpc_chttp2_incoming_metadata_buffer_destroy(&s->metadata_buffer[1]);
-  grpc_slice_buffer_destroy(&s->flow_controlled_buffer);
+  grpc_chttp2_incoming_metadata_buffer_destroy(exec_ctx,
+                                               &s->metadata_buffer[0]);
+  grpc_chttp2_incoming_metadata_buffer_destroy(exec_ctx,
+                                               &s->metadata_buffer[1]);
+  grpc_slice_buffer_destroy_internal(exec_ctx, &s->flow_controlled_buffer);
   GRPC_ERROR_UNREF(s->read_closed_error);
   GRPC_ERROR_UNREF(s->write_closed_error);
 
@@ -781,7 +785,7 @@ void grpc_chttp2_add_incoming_goaway(grpc_exec_ctx *exec_ctx,
   char *msg = grpc_dump_slice(goaway_text, GPR_DUMP_HEX | GPR_DUMP_ASCII);
   GRPC_CHTTP2_IF_TRACING(
       gpr_log(GPR_DEBUG, "got goaway [%d]: %s", goaway_error, msg));
-  grpc_slice_unref(goaway_text);
+  grpc_slice_unref_internal(exec_ctx, goaway_text);
   t->seen_goaway = 1;
   /* lie: use transient failure from the transport to indicate goaway has been
    * received */
@@ -1295,7 +1299,7 @@ static void perform_transport_op_locked(grpc_exec_ctx *exec_ctx,
   if (op->send_goaway) {
     send_goaway(exec_ctx, t,
                 grpc_chttp2_grpc_status_to_http2_error(op->goaway_status),
-                grpc_slice_ref(*op->goaway_message));
+                grpc_slice_ref_internal(*op->goaway_message));
   }
 
   if (op->set_accept_stream) {
@@ -1527,21 +1531,22 @@ void grpc_chttp2_fake_status(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
     char status_string[GPR_LTOA_MIN_BUFSIZE];
     gpr_ltoa(status, status_string);
     grpc_chttp2_incoming_metadata_buffer_add(
-        &s->metadata_buffer[1],
-        grpc_mdelem_from_metadata_strings(
-            GRPC_MDSTR_GRPC_STATUS, grpc_mdstr_from_string(status_string)));
+        &s->metadata_buffer[1], grpc_mdelem_from_metadata_strings(
+                                    exec_ctx, GRPC_MDSTR_GRPC_STATUS,
+                                    grpc_mdstr_from_string(status_string)));
     if (slice) {
       grpc_chttp2_incoming_metadata_buffer_add(
           &s->metadata_buffer[1],
           grpc_mdelem_from_metadata_strings(
-              GRPC_MDSTR_GRPC_MESSAGE,
-              grpc_mdstr_from_slice(grpc_slice_ref(*slice))));
+              exec_ctx, GRPC_MDSTR_GRPC_MESSAGE,
+              grpc_mdstr_from_slice(exec_ctx,
+                                    grpc_slice_ref_internal(*slice))));
     }
     s->published_metadata[1] = GRPC_METADATA_SYNTHESIZED_FROM_FAKE;
     grpc_chttp2_maybe_complete_recv_trailing_metadata(exec_ctx, t, s);
   }
   if (slice) {
-    grpc_slice_unref(*slice);
+    grpc_slice_unref_internal(exec_ctx, *slice);
   }
 }
 
@@ -1697,8 +1702,9 @@ static void close_from_api(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
 
     if (optional_message != NULL) {
       size_t msg_len = strlen(optional_message);
-      GPR_ASSERT(msg_len < 127);
-      message_pfx = grpc_slice_malloc(15);
+      GPR_ASSERT(msg_len <= UINT32_MAX);
+      uint32_t msg_len_len = GRPC_CHTTP2_VARINT_LENGTH((uint32_t)msg_len, 0);
+      message_pfx = grpc_slice_malloc(14 + msg_len_len);
       p = GRPC_SLICE_START_PTR(message_pfx);
       *p++ = 0x40;
       *p++ = 12; /* len(grpc-message) */
@@ -1714,7 +1720,9 @@ static void close_from_api(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
       *p++ = 'a';
       *p++ = 'g';
       *p++ = 'e';
-      *p++ = (uint8_t)msg_len;
+      GRPC_CHTTP2_WRITE_VARINT((uint32_t)msg_len, 0, 0, p,
+                               (uint32_t)msg_len_len);
+      p += msg_len_len;
       GPR_ASSERT(p == GRPC_SLICE_END_PTR(message_pfx));
       len += (uint32_t)GRPC_SLICE_LENGTH(message_pfx);
       len += (uint32_t)msg_len;
@@ -1906,7 +1914,7 @@ static void read_action_locked(grpc_exec_ctx *exec_ctx, void *tp,
     keep_reading = true;
     GRPC_CHTTP2_REF_TRANSPORT(t, "keep_reading");
   }
-  grpc_slice_buffer_reset_and_unref(&t->read_buffer);
+  grpc_slice_buffer_reset_and_unref_internal(exec_ctx, &t->read_buffer);
 
   if (keep_reading) {
     grpc_endpoint_read(exec_ctx, t->ep, &t->read_buffer,
@@ -2013,7 +2021,7 @@ static void incoming_byte_stream_unref(grpc_exec_ctx *exec_ctx,
                                        grpc_chttp2_incoming_byte_stream *bs) {
   if (gpr_unref(&bs->refs)) {
     GRPC_ERROR_UNREF(bs->error);
-    grpc_slice_buffer_destroy(&bs->slices);
+    grpc_slice_buffer_destroy_internal(exec_ctx, &bs->slices);
     gpr_mu_destroy(&bs->slice_mu);
     gpr_free(bs);
   }
diff --git a/src/core/ext/transport/chttp2/transport/frame_rst_stream.c b/src/core/ext/transport/chttp2/transport/frame_rst_stream.c
index b4c5ed769b..20043f5fbf 100644
--- a/src/core/ext/transport/chttp2/transport/frame_rst_stream.c
+++ b/src/core/ext/transport/chttp2/transport/frame_rst_stream.c
@@ -109,7 +109,7 @@ grpc_error *grpc_chttp2_rst_stream_parser_parse(grpc_exec_ctx *exec_ctx,
                       (((uint32_t)p->reason_bytes[2]) << 8) |
                       (((uint32_t)p->reason_bytes[3]));
     grpc_error *error = GRPC_ERROR_NONE;
-    if (reason != GRPC_CHTTP2_NO_ERROR) {
+    if (reason != GRPC_CHTTP2_NO_ERROR || s->header_frames_received < 2) {
       error = grpc_error_set_int(GRPC_ERROR_CREATE("RST_STREAM"),
                                  GRPC_ERROR_INT_HTTP2_ERROR, (intptr_t)reason);
       grpc_status_code status_code = grpc_chttp2_http2_error_to_grpc_status(
diff --git a/src/core/ext/transport/chttp2/transport/hpack_encoder.c b/src/core/ext/transport/chttp2/transport/hpack_encoder.c
index eb68fe3138..49a8326f62 100644
--- a/src/core/ext/transport/chttp2/transport/hpack_encoder.c
+++ b/src/core/ext/transport/chttp2/transport/hpack_encoder.c
@@ -48,6 +48,7 @@
 #include "src/core/ext/transport/chttp2/transport/bin_encoder.h"
 #include "src/core/ext/transport/chttp2/transport/hpack_table.h"
 #include "src/core/ext/transport/chttp2/transport/varint.h"
+#include "src/core/lib/slice/slice_internal.h"
 #include "src/core/lib/transport/metadata.h"
 #include "src/core/lib/transport/static_metadata.h"
 #include "src/core/lib/transport/timeout_encoding.h"
@@ -183,7 +184,8 @@ static void evict_entry(grpc_chttp2_hpack_compressor *c) {
 }
 
 /* add an element to the decoder table */
-static void add_elem(grpc_chttp2_hpack_compressor *c, grpc_mdelem *elem) {
+static void add_elem(grpc_exec_ctx *exec_ctx, grpc_chttp2_hpack_compressor *c,
+                     grpc_mdelem *elem) {
   uint32_t key_hash = elem->key->hash;
   uint32_t elem_hash = GRPC_MDSTR_KV_HASH(key_hash, elem->value->hash);
   uint32_t new_index = c->tail_remote_index + c->table_elems + 1;
@@ -227,12 +229,12 @@ static void add_elem(grpc_chttp2_hpack_compressor *c, grpc_mdelem *elem) {
   } else if (c->indices_elems[HASH_FRAGMENT_2(elem_hash)] <
              c->indices_elems[HASH_FRAGMENT_3(elem_hash)]) {
     /* not there: replace oldest */
-    GRPC_MDELEM_UNREF(c->entries_elems[HASH_FRAGMENT_2(elem_hash)]);
+    GRPC_MDELEM_UNREF(exec_ctx, c->entries_elems[HASH_FRAGMENT_2(elem_hash)]);
     c->entries_elems[HASH_FRAGMENT_2(elem_hash)] = GRPC_MDELEM_REF(elem);
     c->indices_elems[HASH_FRAGMENT_2(elem_hash)] = new_index;
   } else {
     /* not there: replace oldest */
-    GRPC_MDELEM_UNREF(c->entries_elems[HASH_FRAGMENT_3(elem_hash)]);
+    GRPC_MDELEM_UNREF(exec_ctx, c->entries_elems[HASH_FRAGMENT_3(elem_hash)]);
     c->entries_elems[HASH_FRAGMENT_3(elem_hash)] = GRPC_MDELEM_REF(elem);
     c->indices_elems[HASH_FRAGMENT_3(elem_hash)] = new_index;
   }
@@ -251,11 +253,11 @@ static void add_elem(grpc_chttp2_hpack_compressor *c, grpc_mdelem *elem) {
     c->indices_keys[HASH_FRAGMENT_3(key_hash)] = new_index;
   } else if (c->indices_keys[HASH_FRAGMENT_2(key_hash)] <
              c->indices_keys[HASH_FRAGMENT_3(key_hash)]) {
-    GRPC_MDSTR_UNREF(c->entries_keys[HASH_FRAGMENT_2(key_hash)]);
+    GRPC_MDSTR_UNREF(exec_ctx, c->entries_keys[HASH_FRAGMENT_2(key_hash)]);
     c->entries_keys[HASH_FRAGMENT_2(key_hash)] = GRPC_MDSTR_REF(elem->key);
     c->indices_keys[HASH_FRAGMENT_2(key_hash)] = new_index;
   } else {
-    GRPC_MDSTR_UNREF(c->entries_keys[HASH_FRAGMENT_3(key_hash)]);
+    GRPC_MDSTR_UNREF(exec_ctx, c->entries_keys[HASH_FRAGMENT_3(key_hash)]);
     c->entries_keys[HASH_FRAGMENT_3(key_hash)] = GRPC_MDSTR_REF(elem->key);
     c->indices_keys[HASH_FRAGMENT_3(key_hash)] = new_index;
   }
@@ -294,7 +296,7 @@ static void emit_lithdr_incidx(grpc_chttp2_hpack_compressor *c,
                            add_tiny_header_data(st, len_pfx), len_pfx);
   GRPC_CHTTP2_WRITE_VARINT((uint32_t)len_val, 1, huffman_prefix,
                            add_tiny_header_data(st, len_val_len), len_val_len);
-  add_header_data(st, grpc_slice_ref(value_slice));
+  add_header_data(st, grpc_slice_ref_internal(value_slice));
 }
 
 static void emit_lithdr_noidx(grpc_chttp2_hpack_compressor *c,
@@ -311,7 +313,7 @@ static void emit_lithdr_noidx(grpc_chttp2_hpack_compressor *c,
                            add_tiny_header_data(st, len_pfx), len_pfx);
   GRPC_CHTTP2_WRITE_VARINT((uint32_t)len_val, 1, huffman_prefix,
                            add_tiny_header_data(st, len_val_len), len_val_len);
-  add_header_data(st, grpc_slice_ref(value_slice));
+  add_header_data(st, grpc_slice_ref_internal(value_slice));
 }
 
 static void emit_lithdr_incidx_v(grpc_chttp2_hpack_compressor *c,
@@ -327,10 +329,10 @@ static void emit_lithdr_incidx_v(grpc_chttp2_hpack_compressor *c,
   *add_tiny_header_data(st, 1) = 0x40;
   GRPC_CHTTP2_WRITE_VARINT(len_key, 1, 0x00,
                            add_tiny_header_data(st, len_key_len), len_key_len);
-  add_header_data(st, grpc_slice_ref(elem->key->slice));
+  add_header_data(st, grpc_slice_ref_internal(elem->key->slice));
   GRPC_CHTTP2_WRITE_VARINT(len_val, 1, huffman_prefix,
                            add_tiny_header_data(st, len_val_len), len_val_len);
-  add_header_data(st, grpc_slice_ref(value_slice));
+  add_header_data(st, grpc_slice_ref_internal(value_slice));
 }
 
 static void emit_lithdr_noidx_v(grpc_chttp2_hpack_compressor *c,
@@ -346,10 +348,10 @@ static void emit_lithdr_noidx_v(grpc_chttp2_hpack_compressor *c,
   *add_tiny_header_data(st, 1) = 0x00;
   GRPC_CHTTP2_WRITE_VARINT(len_key, 1, 0x00,
                            add_tiny_header_data(st, len_key_len), len_key_len);
-  add_header_data(st, grpc_slice_ref(elem->key->slice));
+  add_header_data(st, grpc_slice_ref_internal(elem->key->slice));
   GRPC_CHTTP2_WRITE_VARINT(len_val, 1, huffman_prefix,
                            add_tiny_header_data(st, len_val_len), len_val_len);
-  add_header_data(st, grpc_slice_ref(value_slice));
+  add_header_data(st, grpc_slice_ref_internal(value_slice));
 }
 
 static void emit_advertise_table_size_change(grpc_chttp2_hpack_compressor *c,
@@ -366,8 +368,8 @@ static uint32_t dynidx(grpc_chttp2_hpack_compressor *c, uint32_t elem_index) {
 }
 
 /* encode an mdelem */
-static void hpack_enc(grpc_chttp2_hpack_compressor *c, grpc_mdelem *elem,
-                      framer_state *st) {
+static void hpack_enc(grpc_exec_ctx *exec_ctx, grpc_chttp2_hpack_compressor *c,
+                      grpc_mdelem *elem, framer_state *st) {
   uint32_t key_hash = elem->key->hash;
   uint32_t elem_hash = GRPC_MDSTR_KV_HASH(key_hash, elem->value->hash);
   size_t decoder_space_usage;
@@ -417,7 +419,7 @@ static void hpack_enc(grpc_chttp2_hpack_compressor *c, grpc_mdelem *elem,
     /* HIT: key (first cuckoo hash) */
     if (should_add_elem) {
       emit_lithdr_incidx(c, dynidx(c, indices_key), elem, st);
-      add_elem(c, elem);
+      add_elem(exec_ctx, c, elem);
       return;
     } else {
       emit_lithdr_noidx(c, dynidx(c, indices_key), elem, st);
@@ -432,7 +434,7 @@ static void hpack_enc(grpc_chttp2_hpack_compressor *c, grpc_mdelem *elem,
     /* HIT: key (first cuckoo hash) */
     if (should_add_elem) {
       emit_lithdr_incidx(c, dynidx(c, indices_key), elem, st);
-      add_elem(c, elem);
+      add_elem(exec_ctx, c, elem);
       return;
     } else {
       emit_lithdr_noidx(c, dynidx(c, indices_key), elem, st);
@@ -445,7 +447,7 @@ static void hpack_enc(grpc_chttp2_hpack_compressor *c, grpc_mdelem *elem,
 
   if (should_add_elem) {
     emit_lithdr_incidx_v(c, elem, st);
-    add_elem(c, elem);
+    add_elem(exec_ctx, c, elem);
     return;
   } else {
     emit_lithdr_noidx_v(c, elem, st);
@@ -457,16 +459,17 @@ static void hpack_enc(grpc_chttp2_hpack_compressor *c, grpc_mdelem *elem,
 #define STRLEN_LIT(x) (sizeof(x) - 1)
 #define TIMEOUT_KEY "grpc-timeout"
 
-static void deadline_enc(grpc_chttp2_hpack_compressor *c, gpr_timespec deadline,
+static void deadline_enc(grpc_exec_ctx *exec_ctx,
+                         grpc_chttp2_hpack_compressor *c, gpr_timespec deadline,
                          framer_state *st) {
   char timeout_str[GRPC_HTTP2_TIMEOUT_ENCODE_MIN_BUFSIZE];
   grpc_mdelem *mdelem;
   grpc_http2_encode_timeout(
       gpr_time_sub(deadline, gpr_now(deadline.clock_type)), timeout_str);
   mdelem = grpc_mdelem_from_metadata_strings(
-      GRPC_MDSTR_GRPC_TIMEOUT, grpc_mdstr_from_string(timeout_str));
-  hpack_enc(c, mdelem, st);
-  GRPC_MDELEM_UNREF(mdelem);
+      exec_ctx, GRPC_MDSTR_GRPC_TIMEOUT, grpc_mdstr_from_string(timeout_str));
+  hpack_enc(exec_ctx, c, mdelem, st);
+  GRPC_MDELEM_UNREF(exec_ctx, mdelem);
 }
 
 static uint32_t elems_for_bytes(uint32_t bytes) { return (bytes + 31) / 32; }
@@ -483,11 +486,12 @@ void grpc_chttp2_hpack_compressor_init(grpc_chttp2_hpack_compressor *c) {
          sizeof(*c->table_elem_size) * c->cap_table_elems);
 }
 
-void grpc_chttp2_hpack_compressor_destroy(grpc_chttp2_hpack_compressor *c) {
+void grpc_chttp2_hpack_compressor_destroy(grpc_exec_ctx *exec_ctx,
+                                          grpc_chttp2_hpack_compressor *c) {
   int i;
   for (i = 0; i < GRPC_CHTTP2_HPACKC_NUM_VALUES; i++) {
-    if (c->entries_keys[i]) GRPC_MDSTR_UNREF(c->entries_keys[i]);
-    if (c->entries_elems[i]) GRPC_MDELEM_UNREF(c->entries_elems[i]);
+    if (c->entries_keys[i]) GRPC_MDSTR_UNREF(exec_ctx, c->entries_keys[i]);
+    if (c->entries_elems[i]) GRPC_MDELEM_UNREF(exec_ctx, c->entries_elems[i]);
   }
   gpr_free(c->table_elem_size);
 }
@@ -542,7 +546,8 @@ void grpc_chttp2_hpack_compressor_set_max_table_size(
   }
 }
 
-void grpc_chttp2_encode_header(grpc_chttp2_hpack_compressor *c,
+void grpc_chttp2_encode_header(grpc_exec_ctx *exec_ctx,
+                               grpc_chttp2_hpack_compressor *c,
                                uint32_t stream_id,
                                grpc_metadata_batch *metadata, int is_eof,
                                size_t max_frame_size,
@@ -571,11 +576,11 @@ void grpc_chttp2_encode_header(grpc_chttp2_hpack_compressor *c,
   }
   grpc_metadata_batch_assert_ok(metadata);
   for (l = metadata->list.head; l; l = l->next) {
-    hpack_enc(c, l->md, &st);
+    hpack_enc(exec_ctx, c, l->md, &st);
   }
   deadline = metadata->deadline;
   if (gpr_time_cmp(deadline, gpr_inf_future(deadline.clock_type)) != 0) {
-    deadline_enc(c, deadline, &st);
+    deadline_enc(exec_ctx, c, deadline, &st);
   }
 
   finish_frame(&st, 1, is_eof);
diff --git a/src/core/ext/transport/chttp2/transport/hpack_encoder.h b/src/core/ext/transport/chttp2/transport/hpack_encoder.h
index bcbd675ca2..3a35496ec8 100644
--- a/src/core/ext/transport/chttp2/transport/hpack_encoder.h
+++ b/src/core/ext/transport/chttp2/transport/hpack_encoder.h
@@ -83,13 +83,15 @@ typedef struct {
 } grpc_chttp2_hpack_compressor;
 
 void grpc_chttp2_hpack_compressor_init(grpc_chttp2_hpack_compressor *c);
-void grpc_chttp2_hpack_compressor_destroy(grpc_chttp2_hpack_compressor *c);
+void grpc_chttp2_hpack_compressor_destroy(grpc_exec_ctx *exec_ctx,
+                                          grpc_chttp2_hpack_compressor *c);
 void grpc_chttp2_hpack_compressor_set_max_table_size(
     grpc_chttp2_hpack_compressor *c, uint32_t max_table_size);
 void grpc_chttp2_hpack_compressor_set_max_usable_size(
     grpc_chttp2_hpack_compressor *c, uint32_t max_table_size);
 
-void grpc_chttp2_encode_header(grpc_chttp2_hpack_compressor *c, uint32_t id,
+void grpc_chttp2_encode_header(grpc_exec_ctx *exec_ctx,
+                               grpc_chttp2_hpack_compressor *c, uint32_t id,
                                grpc_metadata_batch *metadata, int is_eof,
                                size_t max_frame_size,
                                grpc_transport_one_way_stats *stats,
diff --git a/src/core/ext/transport/chttp2/transport/hpack_parser.c b/src/core/ext/transport/chttp2/transport/hpack_parser.c
index 64ce07b2f7..8b91cc760b 100644
--- a/src/core/ext/transport/chttp2/transport/hpack_parser.c
+++ b/src/core/ext/transport/chttp2/transport/hpack_parser.c
@@ -670,11 +670,11 @@ static const uint8_t inverse_base64[256] = {
 static grpc_error *on_hdr(grpc_exec_ctx *exec_ctx, grpc_chttp2_hpack_parser *p,
                           grpc_mdelem *md, int add_to_table) {
   if (add_to_table) {
-    grpc_error *err = grpc_chttp2_hptbl_add(&p->table, md);
+    grpc_error *err = grpc_chttp2_hptbl_add(exec_ctx, &p->table, md);
     if (err != GRPC_ERROR_NONE) return err;
   }
   if (p->on_header == NULL) {
-    GRPC_MDELEM_UNREF(md);
+    GRPC_MDELEM_UNREF(exec_ctx, md);
     return GRPC_ERROR_CREATE("on_header callback not set");
   }
   p->on_header(exec_ctx, p->on_header_user_data, md);
@@ -815,10 +815,10 @@ static grpc_error *finish_lithdr_incidx(grpc_exec_ctx *exec_ctx,
                                         const uint8_t *end) {
   grpc_mdelem *md = grpc_chttp2_hptbl_lookup(&p->table, p->index);
   GPR_ASSERT(md != NULL); /* handled in string parsing */
-  grpc_error *err = on_hdr(
-      exec_ctx, p, grpc_mdelem_from_metadata_strings(GRPC_MDSTR_REF(md->key),
-                                                     take_string(p, &p->value)),
-      1);
+  grpc_error *err = on_hdr(exec_ctx, p, grpc_mdelem_from_metadata_strings(
+                                            exec_ctx, GRPC_MDSTR_REF(md->key),
+                                            take_string(p, &p->value)),
+                           1);
   if (err != GRPC_ERROR_NONE) return parse_error(exec_ctx, p, cur, end, err);
   return parse_begin(exec_ctx, p, cur, end);
 }
@@ -828,10 +828,10 @@ static grpc_error *finish_lithdr_incidx_v(grpc_exec_ctx *exec_ctx,
                                           grpc_chttp2_hpack_parser *p,
                                           const uint8_t *cur,
                                           const uint8_t *end) {
-  grpc_error *err = on_hdr(
-      exec_ctx, p, grpc_mdelem_from_metadata_strings(take_string(p, &p->key),
-                                                     take_string(p, &p->value)),
-      1);
+  grpc_error *err = on_hdr(exec_ctx, p, grpc_mdelem_from_metadata_strings(
+                                            exec_ctx, take_string(p, &p->key),
+                                            take_string(p, &p->value)),
+                           1);
   if (err != GRPC_ERROR_NONE) return parse_error(exec_ctx, p, cur, end, err);
   return parse_begin(exec_ctx, p, cur, end);
 }
@@ -883,10 +883,10 @@ static grpc_error *finish_lithdr_notidx(grpc_exec_ctx *exec_ctx,
                                         const uint8_t *end) {
   grpc_mdelem *md = grpc_chttp2_hptbl_lookup(&p->table, p->index);
   GPR_ASSERT(md != NULL); /* handled in string parsing */
-  grpc_error *err = on_hdr(
-      exec_ctx, p, grpc_mdelem_from_metadata_strings(GRPC_MDSTR_REF(md->key),
-                                                     take_string(p, &p->value)),
-      0);
+  grpc_error *err = on_hdr(exec_ctx, p, grpc_mdelem_from_metadata_strings(
+                                            exec_ctx, GRPC_MDSTR_REF(md->key),
+                                            take_string(p, &p->value)),
+                           0);
   if (err != GRPC_ERROR_NONE) return parse_error(exec_ctx, p, cur, end, err);
   return parse_begin(exec_ctx, p, cur, end);
 }
@@ -896,10 +896,10 @@ static grpc_error *finish_lithdr_notidx_v(grpc_exec_ctx *exec_ctx,
                                           grpc_chttp2_hpack_parser *p,
                                           const uint8_t *cur,
                                           const uint8_t *end) {
-  grpc_error *err = on_hdr(
-      exec_ctx, p, grpc_mdelem_from_metadata_strings(take_string(p, &p->key),
-                                                     take_string(p, &p->value)),
-      0);
+  grpc_error *err = on_hdr(exec_ctx, p, grpc_mdelem_from_metadata_strings(
+                                            exec_ctx, take_string(p, &p->key),
+                                            take_string(p, &p->value)),
+                           0);
   if (err != GRPC_ERROR_NONE) return parse_error(exec_ctx, p, cur, end, err);
   return parse_begin(exec_ctx, p, cur, end);
 }
@@ -951,10 +951,10 @@ static grpc_error *finish_lithdr_nvridx(grpc_exec_ctx *exec_ctx,
                                         const uint8_t *end) {
   grpc_mdelem *md = grpc_chttp2_hptbl_lookup(&p->table, p->index);
   GPR_ASSERT(md != NULL); /* handled in string parsing */
-  grpc_error *err = on_hdr(
-      exec_ctx, p, grpc_mdelem_from_metadata_strings(GRPC_MDSTR_REF(md->key),
-                                                     take_string(p, &p->value)),
-      0);
+  grpc_error *err = on_hdr(exec_ctx, p, grpc_mdelem_from_metadata_strings(
+                                            exec_ctx, GRPC_MDSTR_REF(md->key),
+                                            take_string(p, &p->value)),
+                           0);
   if (err != GRPC_ERROR_NONE) return parse_error(exec_ctx, p, cur, end, err);
   return parse_begin(exec_ctx, p, cur, end);
 }
@@ -964,10 +964,10 @@ static grpc_error *finish_lithdr_nvridx_v(grpc_exec_ctx *exec_ctx,
                                           grpc_chttp2_hpack_parser *p,
                                           const uint8_t *cur,
                                           const uint8_t *end) {
-  grpc_error *err = on_hdr(
-      exec_ctx, p, grpc_mdelem_from_metadata_strings(take_string(p, &p->key),
-                                                     take_string(p, &p->value)),
-      0);
+  grpc_error *err = on_hdr(exec_ctx, p, grpc_mdelem_from_metadata_strings(
+                                            exec_ctx, take_string(p, &p->key),
+                                            take_string(p, &p->value)),
+                           0);
   if (err != GRPC_ERROR_NONE) return parse_error(exec_ctx, p, cur, end, err);
   return parse_begin(exec_ctx, p, cur, end);
 }
@@ -1020,7 +1020,7 @@ static grpc_error *finish_max_tbl_size(grpc_exec_ctx *exec_ctx,
     gpr_log(GPR_INFO, "MAX TABLE SIZE: %d", p->index);
   }
   grpc_error *err =
-      grpc_chttp2_hptbl_set_current_table_size(&p->table, p->index);
+      grpc_chttp2_hptbl_set_current_table_size(exec_ctx, &p->table, p->index);
   if (err != GRPC_ERROR_NONE) return parse_error(exec_ctx, p, cur, end, err);
   return parse_begin(exec_ctx, p, cur, end);
 }
@@ -1534,7 +1534,8 @@ static grpc_error *parse_value_string_with_literal_key(
 
 /* PUBLIC INTERFACE */
 
-void grpc_chttp2_hpack_parser_init(grpc_chttp2_hpack_parser *p) {
+void grpc_chttp2_hpack_parser_init(grpc_exec_ctx *exec_ctx,
+                                   grpc_chttp2_hpack_parser *p) {
   p->on_header = NULL;
   p->on_header_user_data = NULL;
   p->state = parse_begin;
@@ -1546,7 +1547,7 @@ void grpc_chttp2_hpack_parser_init(grpc_chttp2_hpack_parser *p) {
   p->value.length = 0;
   p->dynamic_table_update_allowed = 2;
   p->last_error = GRPC_ERROR_NONE;
-  grpc_chttp2_hptbl_init(&p->table);
+  grpc_chttp2_hptbl_init(exec_ctx, &p->table);
 }
 
 void grpc_chttp2_hpack_parser_set_has_priority(grpc_chttp2_hpack_parser *p) {
@@ -1554,8 +1555,9 @@ void grpc_chttp2_hpack_parser_set_has_priority(grpc_chttp2_hpack_parser *p) {
   p->state = parse_stream_dep0;
 }
 
-void grpc_chttp2_hpack_parser_destroy(grpc_chttp2_hpack_parser *p) {
-  grpc_chttp2_hptbl_destroy(&p->table);
+void grpc_chttp2_hpack_parser_destroy(grpc_exec_ctx *exec_ctx,
+                                      grpc_chttp2_hpack_parser *p) {
+  grpc_chttp2_hptbl_destroy(exec_ctx, &p->table);
   GRPC_ERROR_UNREF(p->last_error);
   gpr_free(p->key.str);
   gpr_free(p->value.str);
diff --git a/src/core/ext/transport/chttp2/transport/hpack_parser.h b/src/core/ext/transport/chttp2/transport/hpack_parser.h
index a39bf466cd..52ccf1e7a7 100644
--- a/src/core/ext/transport/chttp2/transport/hpack_parser.h
+++ b/src/core/ext/transport/chttp2/transport/hpack_parser.h
@@ -99,8 +99,10 @@ struct grpc_chttp2_hpack_parser {
   grpc_chttp2_hptbl table;
 };
 
-void grpc_chttp2_hpack_parser_init(grpc_chttp2_hpack_parser *p);
-void grpc_chttp2_hpack_parser_destroy(grpc_chttp2_hpack_parser *p);
+void grpc_chttp2_hpack_parser_init(grpc_exec_ctx *exec_ctx,
+                                   grpc_chttp2_hpack_parser *p);
+void grpc_chttp2_hpack_parser_destroy(grpc_exec_ctx *exec_ctx,
+                                      grpc_chttp2_hpack_parser *p);
 
 void grpc_chttp2_hpack_parser_set_has_priority(grpc_chttp2_hpack_parser *p);
 
diff --git a/src/core/ext/transport/chttp2/transport/hpack_table.c b/src/core/ext/transport/chttp2/transport/hpack_table.c
index 2dc793d304..26d4036d49 100644
--- a/src/core/ext/transport/chttp2/transport/hpack_table.c
+++ b/src/core/ext/transport/chttp2/transport/hpack_table.c
@@ -179,7 +179,7 @@ static uint32_t entries_for_bytes(uint32_t bytes) {
          GRPC_CHTTP2_HPACK_ENTRY_OVERHEAD;
 }
 
-void grpc_chttp2_hptbl_init(grpc_chttp2_hptbl *tbl) {
+void grpc_chttp2_hptbl_init(grpc_exec_ctx *exec_ctx, grpc_chttp2_hptbl *tbl) {
   size_t i;
 
   memset(tbl, 0, sizeof(*tbl));
@@ -190,18 +190,20 @@ void grpc_chttp2_hptbl_init(grpc_chttp2_hptbl *tbl) {
   tbl->ents = gpr_malloc(sizeof(*tbl->ents) * tbl->cap_entries);
   memset(tbl->ents, 0, sizeof(*tbl->ents) * tbl->cap_entries);
   for (i = 1; i <= GRPC_CHTTP2_LAST_STATIC_ENTRY; i++) {
-    tbl->static_ents[i - 1] =
-        grpc_mdelem_from_strings(static_table[i].key, static_table[i].value);
+    tbl->static_ents[i - 1] = grpc_mdelem_from_strings(
+        exec_ctx, static_table[i].key, static_table[i].value);
   }
 }
 
-void grpc_chttp2_hptbl_destroy(grpc_chttp2_hptbl *tbl) {
+void grpc_chttp2_hptbl_destroy(grpc_exec_ctx *exec_ctx,
+                               grpc_chttp2_hptbl *tbl) {
   size_t i;
   for (i = 0; i < GRPC_CHTTP2_LAST_STATIC_ENTRY; i++) {
-    GRPC_MDELEM_UNREF(tbl->static_ents[i]);
+    GRPC_MDELEM_UNREF(exec_ctx, tbl->static_ents[i]);
   }
   for (i = 0; i < tbl->num_ents; i++) {
-    GRPC_MDELEM_UNREF(tbl->ents[(tbl->first_ent + i) % tbl->cap_entries]);
+    GRPC_MDELEM_UNREF(exec_ctx,
+                      tbl->ents[(tbl->first_ent + i) % tbl->cap_entries]);
   }
   gpr_free(tbl->ents);
 }
@@ -224,7 +226,7 @@ grpc_mdelem *grpc_chttp2_hptbl_lookup(const grpc_chttp2_hptbl *tbl,
 }
 
 /* Evict one element from the table */
-static void evict1(grpc_chttp2_hptbl *tbl) {
+static void evict1(grpc_exec_ctx *exec_ctx, grpc_chttp2_hptbl *tbl) {
   grpc_mdelem *first_ent = tbl->ents[tbl->first_ent];
   size_t elem_bytes = GRPC_SLICE_LENGTH(first_ent->key->slice) +
                       GRPC_SLICE_LENGTH(first_ent->value->slice) +
@@ -233,7 +235,7 @@ static void evict1(grpc_chttp2_hptbl *tbl) {
   tbl->mem_used -= (uint32_t)elem_bytes;
   tbl->first_ent = ((tbl->first_ent + 1) % tbl->cap_entries);
   tbl->num_ents--;
-  GRPC_MDELEM_UNREF(first_ent);
+  GRPC_MDELEM_UNREF(exec_ctx, first_ent);
 }
 
 static void rebuild_ents(grpc_chttp2_hptbl *tbl, uint32_t new_cap) {
@@ -249,7 +251,8 @@ static void rebuild_ents(grpc_chttp2_hptbl *tbl, uint32_t new_cap) {
   tbl->first_ent = 0;
 }
 
-void grpc_chttp2_hptbl_set_max_bytes(grpc_chttp2_hptbl *tbl,
+void grpc_chttp2_hptbl_set_max_bytes(grpc_exec_ctx *exec_ctx,
+                                     grpc_chttp2_hptbl *tbl,
                                      uint32_t max_bytes) {
   if (tbl->max_bytes == max_bytes) {
     return;
@@ -258,12 +261,13 @@ void grpc_chttp2_hptbl_set_max_bytes(grpc_chttp2_hptbl *tbl,
     gpr_log(GPR_DEBUG, "Update hpack parser max size to %d", max_bytes);
   }
   while (tbl->mem_used > max_bytes) {
-    evict1(tbl);
+    evict1(exec_ctx, tbl);
   }
   tbl->max_bytes = max_bytes;
 }
 
-grpc_error *grpc_chttp2_hptbl_set_current_table_size(grpc_chttp2_hptbl *tbl,
+grpc_error *grpc_chttp2_hptbl_set_current_table_size(grpc_exec_ctx *exec_ctx,
+                                                     grpc_chttp2_hptbl *tbl,
                                                      uint32_t bytes) {
   if (tbl->current_table_bytes == bytes) {
     return GRPC_ERROR_NONE;
@@ -281,7 +285,7 @@ grpc_error *grpc_chttp2_hptbl_set_current_table_size(grpc_chttp2_hptbl *tbl,
     gpr_log(GPR_DEBUG, "Update hpack parser table size to %d", bytes);
   }
   while (tbl->mem_used > bytes) {
-    evict1(tbl);
+    evict1(exec_ctx, tbl);
   }
   tbl->current_table_bytes = bytes;
   tbl->max_entries = entries_for_bytes(bytes);
@@ -296,7 +300,8 @@ grpc_error *grpc_chttp2_hptbl_set_current_table_size(grpc_chttp2_hptbl *tbl,
   return GRPC_ERROR_NONE;
 }
 
-grpc_error *grpc_chttp2_hptbl_add(grpc_chttp2_hptbl *tbl, grpc_mdelem *md) {
+grpc_error *grpc_chttp2_hptbl_add(grpc_exec_ctx *exec_ctx,
+                                  grpc_chttp2_hptbl *tbl, grpc_mdelem *md) {
   /* determine how many bytes of buffer this entry represents */
   size_t elem_bytes = GRPC_SLICE_LENGTH(md->key->slice) +
                       GRPC_SLICE_LENGTH(md->value->slice) +
@@ -326,14 +331,14 @@ grpc_error *grpc_chttp2_hptbl_add(grpc_chttp2_hptbl *tbl, grpc_mdelem *md) {
      * empty table.
      */
     while (tbl->num_ents) {
-      evict1(tbl);
+      evict1(exec_ctx, tbl);
     }
     return GRPC_ERROR_NONE;
   }
 
   /* evict entries to ensure no overflow */
   while (elem_bytes > (size_t)tbl->current_table_bytes - tbl->mem_used) {
-    evict1(tbl);
+    evict1(exec_ctx, tbl);
   }
 
   /* copy the finalized entry in */
diff --git a/src/core/ext/transport/chttp2/transport/hpack_table.h b/src/core/ext/transport/chttp2/transport/hpack_table.h
index 2ca130e64b..144574ef06 100644
--- a/src/core/ext/transport/chttp2/transport/hpack_table.h
+++ b/src/core/ext/transport/chttp2/transport/hpack_table.h
@@ -84,18 +84,21 @@ typedef struct {
 } grpc_chttp2_hptbl;
 
 /* initialize a hpack table */
-void grpc_chttp2_hptbl_init(grpc_chttp2_hptbl *tbl);
-void grpc_chttp2_hptbl_destroy(grpc_chttp2_hptbl *tbl);
-void grpc_chttp2_hptbl_set_max_bytes(grpc_chttp2_hptbl *tbl,
+void grpc_chttp2_hptbl_init(grpc_exec_ctx *exec_ctx, grpc_chttp2_hptbl *tbl);
+void grpc_chttp2_hptbl_destroy(grpc_exec_ctx *exec_ctx, grpc_chttp2_hptbl *tbl);
+void grpc_chttp2_hptbl_set_max_bytes(grpc_exec_ctx *exec_ctx,
+                                     grpc_chttp2_hptbl *tbl,
                                      uint32_t max_bytes);
-grpc_error *grpc_chttp2_hptbl_set_current_table_size(grpc_chttp2_hptbl *tbl,
+grpc_error *grpc_chttp2_hptbl_set_current_table_size(grpc_exec_ctx *exec_ctx,
+                                                     grpc_chttp2_hptbl *tbl,
                                                      uint32_t bytes);
 
 /* lookup a table entry based on its hpack index */
 grpc_mdelem *grpc_chttp2_hptbl_lookup(const grpc_chttp2_hptbl *tbl,
                                       uint32_t index);
 /* add a table entry to the index */
-grpc_error *grpc_chttp2_hptbl_add(grpc_chttp2_hptbl *tbl,
+grpc_error *grpc_chttp2_hptbl_add(grpc_exec_ctx *exec_ctx,
+                                  grpc_chttp2_hptbl *tbl,
                                   grpc_mdelem *md) GRPC_MUST_USE_RESULT;
 /* Find a key/value pair in the table... returns the index in the table of the
    most similar entry, or 0 if the value was not found */
diff --git a/src/core/ext/transport/chttp2/transport/incoming_metadata.c b/src/core/ext/transport/chttp2/transport/incoming_metadata.c
index 3e463a7995..5d1094999c 100644
--- a/src/core/ext/transport/chttp2/transport/incoming_metadata.c
+++ b/src/core/ext/transport/chttp2/transport/incoming_metadata.c
@@ -46,11 +46,11 @@ void grpc_chttp2_incoming_metadata_buffer_init(
 }
 
 void grpc_chttp2_incoming_metadata_buffer_destroy(
-    grpc_chttp2_incoming_metadata_buffer *buffer) {
+    grpc_exec_ctx *exec_ctx, grpc_chttp2_incoming_metadata_buffer *buffer) {
   size_t i;
   if (!buffer->published) {
     for (i = 0; i < buffer->count; i++) {
-      GRPC_MDELEM_UNREF(buffer->elems[i].md);
+      GRPC_MDELEM_UNREF(exec_ctx, buffer->elems[i].md);
     }
   }
   gpr_free(buffer->elems);
diff --git a/src/core/ext/transport/chttp2/transport/incoming_metadata.h b/src/core/ext/transport/chttp2/transport/incoming_metadata.h
index df4343b93e..7a0c4da15f 100644
--- a/src/core/ext/transport/chttp2/transport/incoming_metadata.h
+++ b/src/core/ext/transport/chttp2/transport/incoming_metadata.h
@@ -49,7 +49,7 @@ typedef struct {
 void grpc_chttp2_incoming_metadata_buffer_init(
     grpc_chttp2_incoming_metadata_buffer *buffer);
 void grpc_chttp2_incoming_metadata_buffer_destroy(
-    grpc_chttp2_incoming_metadata_buffer *buffer);
+    grpc_exec_ctx *exec_ctx, grpc_chttp2_incoming_metadata_buffer *buffer);
 void grpc_chttp2_incoming_metadata_buffer_publish(
     grpc_chttp2_incoming_metadata_buffer *buffer, grpc_metadata_batch *batch);
 
diff --git a/src/core/ext/transport/chttp2/transport/parsing.c b/src/core/ext/transport/chttp2/transport/parsing.c
index b601cf282d..4373391e44 100644
--- a/src/core/ext/transport/chttp2/transport/parsing.c
+++ b/src/core/ext/transport/chttp2/transport/parsing.c
@@ -336,7 +336,7 @@ static grpc_error *skip_parser(grpc_exec_ctx *exec_ctx, void *parser,
 }
 
 static void skip_header(grpc_exec_ctx *exec_ctx, void *tp, grpc_mdelem *md) {
-  GRPC_MDELEM_UNREF(md);
+  GRPC_MDELEM_UNREF(exec_ctx, md);
 }
 
 static grpc_error *init_skip_frame_parser(grpc_exec_ctx *exec_ctx,
@@ -482,7 +482,7 @@ static void on_initial_header(grpc_exec_ctx *exec_ctx, void *tp,
     grpc_chttp2_incoming_metadata_buffer_set_deadline(
         &s->metadata_buffer[0],
         gpr_time_add(gpr_now(GPR_CLOCK_MONOTONIC), *cached_timeout));
-    GRPC_MDELEM_UNREF(md);
+    GRPC_MDELEM_UNREF(exec_ctx, md);
   } else {
     const size_t new_size = s->metadata_buffer[0].size + GRPC_MDELEM_LENGTH(md);
     const size_t metadata_size_limit =
@@ -500,7 +500,7 @@ static void on_initial_header(grpc_exec_ctx *exec_ctx, void *tp,
               GRPC_ERROR_INT_GRPC_STATUS, GRPC_STATUS_RESOURCE_EXHAUSTED));
       grpc_chttp2_parsing_become_skip_parser(exec_ctx, t);
       s->seen_error = true;
-      GRPC_MDELEM_UNREF(md);
+      GRPC_MDELEM_UNREF(exec_ctx, md);
     } else {
       grpc_chttp2_incoming_metadata_buffer_add(&s->metadata_buffer[0], md);
     }
@@ -543,7 +543,7 @@ static void on_trailing_header(grpc_exec_ctx *exec_ctx, void *tp,
             GRPC_ERROR_INT_GRPC_STATUS, GRPC_STATUS_RESOURCE_EXHAUSTED));
     grpc_chttp2_parsing_become_skip_parser(exec_ctx, t);
     s->seen_error = true;
-    GRPC_MDELEM_UNREF(md);
+    GRPC_MDELEM_UNREF(exec_ctx, md);
   } else {
     grpc_chttp2_incoming_metadata_buffer_add(&s->metadata_buffer[1], md);
   }
@@ -717,7 +717,7 @@ static grpc_error *init_settings_frame_parser(grpc_exec_ctx *exec_ctx,
     memcpy(t->settings[GRPC_ACKED_SETTINGS], t->settings[GRPC_SENT_SETTINGS],
            GRPC_CHTTP2_NUM_SETTINGS * sizeof(uint32_t));
     grpc_chttp2_hptbl_set_max_bytes(
-        &t->hpack_parser.table,
+        exec_ctx, &t->hpack_parser.table,
         t->settings[GRPC_ACKED_SETTINGS]
                    [GRPC_CHTTP2_SETTINGS_HEADER_TABLE_SIZE]);
     t->sent_local_settings = 0;
diff --git a/src/core/ext/transport/chttp2/transport/writing.c b/src/core/ext/transport/chttp2/transport/writing.c
index 57648a704d..6ef3b147be 100644
--- a/src/core/ext/transport/chttp2/transport/writing.c
+++ b/src/core/ext/transport/chttp2/transport/writing.c
@@ -39,6 +39,7 @@
 
 #include "src/core/ext/transport/chttp2/transport/http2_errors.h"
 #include "src/core/lib/profiling/timers.h"
+#include "src/core/lib/slice/slice_internal.h"
 
 static void add_to_write_list(grpc_chttp2_write_cb **list,
                               grpc_chttp2_write_cb *cb) {
@@ -172,7 +173,7 @@ bool grpc_chttp2_begin_write(grpc_exec_ctx *exec_ctx,
     /* send initial metadata if it's available */
     if (!sent_initial_metadata && s->send_initial_metadata) {
       grpc_chttp2_encode_header(
-          &t->hpack_compressor, s->id, s->send_initial_metadata, 0,
+          exec_ctx, &t->hpack_compressor, s->id, s->send_initial_metadata, 0,
           t->settings[GRPC_ACKED_SETTINGS][GRPC_CHTTP2_SETTINGS_MAX_FRAME_SIZE],
           &s->stats.outgoing, &t->outbuf);
       s->send_initial_metadata = NULL;
@@ -251,9 +252,9 @@ bool grpc_chttp2_begin_write(grpc_exec_ctx *exec_ctx,
                                   &s->stats.outgoing, &t->outbuf);
         } else {
           grpc_chttp2_encode_header(
-              &t->hpack_compressor, s->id, s->send_trailing_metadata, true,
-              t->settings[GRPC_ACKED_SETTINGS]
-                         [GRPC_CHTTP2_SETTINGS_MAX_FRAME_SIZE],
+              exec_ctx, &t->hpack_compressor, s->id, s->send_trailing_metadata,
+              true, t->settings[GRPC_ACKED_SETTINGS]
+                               [GRPC_CHTTP2_SETTINGS_MAX_FRAME_SIZE],
               &s->stats.outgoing, &t->outbuf);
         }
         s->send_trailing_metadata = NULL;
@@ -325,7 +326,7 @@ void grpc_chttp2_end_write(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
     }
     GRPC_CHTTP2_STREAM_UNREF(exec_ctx, s, "chttp2_writing:end");
   }
-  grpc_slice_buffer_reset_and_unref(&t->outbuf);
+  grpc_slice_buffer_reset_and_unref_internal(exec_ctx, &t->outbuf);
   GRPC_ERROR_UNREF(error);
   GPR_TIMER_END("grpc_chttp2_end_write", 0);
 }
diff --git a/src/core/ext/transport/cronet/transport/cronet_transport.c b/src/core/ext/transport/cronet/transport/cronet_transport.c
index df0a769f6c..296c406324 100644
--- a/src/core/ext/transport/cronet/transport/cronet_transport.c
+++ b/src/core/ext/transport/cronet/transport/cronet_transport.c
@@ -427,6 +427,7 @@ static void on_response_headers_received(
     cronet_bidirectional_stream *stream,
     const cronet_bidirectional_stream_header_array *headers,
     const char *negotiated_protocol) {
+  grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
   CRONET_LOG(GPR_DEBUG, "R: on_response_headers_received(%p, %p, %s)", stream,
              headers, negotiated_protocol);
   stream_obj *s = (stream_obj *)stream->annotation;
@@ -438,7 +439,7 @@ static void on_response_headers_received(
     grpc_chttp2_incoming_metadata_buffer_add(
         &s->state.rs.initial_metadata,
         grpc_mdelem_from_metadata_strings(
-            grpc_mdstr_from_string(headers->headers[i].key),
+            &exec_ctx, grpc_mdstr_from_string(headers->headers[i].key),
             grpc_mdstr_from_string(headers->headers[i].value)));
   }
   s->state.state_callback_received[OP_RECV_INITIAL_METADATA] = true;
@@ -455,6 +456,7 @@ static void on_response_headers_received(
                                      s->state.rs.remaining_bytes);
   }
   gpr_mu_unlock(&s->mu);
+  grpc_exec_ctx_finish(&exec_ctx);
   execute_from_storage(s);
 }
 
@@ -520,6 +522,7 @@ static void on_read_completed(cronet_bidirectional_stream *stream, char *data,
 static void on_response_trailers_received(
     cronet_bidirectional_stream *stream,
     const cronet_bidirectional_stream_header_array *trailers) {
+  grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
   CRONET_LOG(GPR_DEBUG, "R: on_response_trailers_received(%p,%p)", stream,
              trailers);
   stream_obj *s = (stream_obj *)stream->annotation;
@@ -534,7 +537,7 @@ static void on_response_trailers_received(
     grpc_chttp2_incoming_metadata_buffer_add(
         &s->state.rs.trailing_metadata,
         grpc_mdelem_from_metadata_strings(
-            grpc_mdstr_from_string(trailers->headers[i].key),
+            &exec_ctx, grpc_mdstr_from_string(trailers->headers[i].key),
             grpc_mdstr_from_string(trailers->headers[i].value)));
     s->state.rs.trailing_metadata_valid = true;
     if (0 == strcmp(trailers->headers[i].key, "grpc-status") &&
@@ -554,8 +557,10 @@ static void on_response_trailers_received(
     s->state.state_op_done[OP_SEND_TRAILING_METADATA] = true;
 
     gpr_mu_unlock(&s->mu);
+    grpc_exec_ctx_finish(&exec_ctx);
   } else {
     gpr_mu_unlock(&s->mu);
+    grpc_exec_ctx_finish(&exec_ctx);
     execute_from_storage(s);
   }
 }
diff --git a/src/core/lib/README.md b/src/core/lib/README.md
new file mode 100644
index 0000000000..69b6bce2d9
--- /dev/null
+++ b/src/core/lib/README.md
@@ -0,0 +1,6 @@
+Required elements of gRPC Core: Each module in this directory is required to
+build gRPC. If it's possible to envisage a configuration where code is not
+required, then that code belongs in ext/ instead.
+
+NOTE: The movement of code between lib and ext is an ongoing effort, so this
+directory currently contains too much of the core library.
diff --git a/src/core/lib/channel/README.md b/src/core/lib/channel/README.md
new file mode 100644
index 0000000000..2dfcfe6e66
--- /dev/null
+++ b/src/core/lib/channel/README.md
@@ -0,0 +1,4 @@
+# Channel
+
+Provides channel/call stack implementation, and implementation of common filters
+for that implementation.
diff --git a/src/core/lib/channel/channel_args.c b/src/core/lib/channel/channel_args.c
index 401a2ad4fe..1a099ac437 100644
--- a/src/core/lib/channel/channel_args.c
+++ b/src/core/lib/channel/channel_args.c
@@ -184,7 +184,7 @@ grpc_channel_args *grpc_channel_args_normalize(const grpc_channel_args *a) {
   return b;
 }
 
-void grpc_channel_args_destroy(grpc_channel_args *a) {
+void grpc_channel_args_destroy(grpc_exec_ctx *exec_ctx, grpc_channel_args *a) {
   size_t i;
   if (!a) return;
   for (i = 0; i < a->num_args; i++) {
@@ -195,7 +195,8 @@ void grpc_channel_args_destroy(grpc_channel_args *a) {
       case GRPC_ARG_INTEGER:
         break;
       case GRPC_ARG_POINTER:
-        a->args[i].value.pointer.vtable->destroy(a->args[i].value.pointer.p);
+        a->args[i].value.pointer.vtable->destroy(exec_ctx,
+                                                 a->args[i].value.pointer.p);
         break;
     }
     gpr_free(a->args[i].key);
@@ -249,7 +250,8 @@ static int find_compression_algorithm_states_bitset(const grpc_channel_args *a,
 }
 
 grpc_channel_args *grpc_channel_args_compression_algorithm_set_state(
-    grpc_channel_args **a, grpc_compression_algorithm algorithm, int state) {
+    grpc_exec_ctx *exec_ctx, grpc_channel_args **a,
+    grpc_compression_algorithm algorithm, int state) {
   int *states_arg = NULL;
   grpc_channel_args *result = *a;
   const int states_arg_found =
@@ -282,7 +284,7 @@ grpc_channel_args *grpc_channel_args_compression_algorithm_set_state(
       GPR_BITCLEAR((unsigned *)&tmp.value.integer, algorithm);
     }
     result = grpc_channel_args_copy_and_add(*a, &tmp, 1);
-    grpc_channel_args_destroy(*a);
+    grpc_channel_args_destroy(exec_ctx, *a);
     *a = result;
   }
   return result;
diff --git a/src/core/lib/channel/channel_args.h b/src/core/lib/channel/channel_args.h
index 88fc0e37a3..5c7d31f8bb 100644
--- a/src/core/lib/channel/channel_args.h
+++ b/src/core/lib/channel/channel_args.h
@@ -68,7 +68,7 @@ grpc_channel_args *grpc_channel_args_merge(const grpc_channel_args *a,
                                            const grpc_channel_args *b);
 
 /** Destroy arguments created by \a grpc_channel_args_copy */
-void grpc_channel_args_destroy(grpc_channel_args *a);
+void grpc_channel_args_destroy(grpc_exec_ctx *exec_ctx, grpc_channel_args *a);
 
 /** Returns the compression algorithm set in \a a. */
 grpc_compression_algorithm grpc_channel_args_get_compression_algorithm(
@@ -88,7 +88,8 @@ grpc_channel_args *grpc_channel_args_set_compression_algorithm(
  * modified to point to the returned instance (which may be different from the
  * input value of \a a). */
 grpc_channel_args *grpc_channel_args_compression_algorithm_set_state(
-    grpc_channel_args **a, grpc_compression_algorithm algorithm, int enabled);
+    grpc_exec_ctx *exec_ctx, grpc_channel_args **a,
+    grpc_compression_algorithm algorithm, int enabled);
 
 /** Returns the bitset representing the support state (true for enabled, false
  * for disabled) for compression algorithms.
diff --git a/src/core/lib/channel/channel_stack.c b/src/core/lib/channel/channel_stack.c
index cddd84fcca..8f08b427fb 100644
--- a/src/core/lib/channel/channel_stack.c
+++ b/src/core/lib/channel/channel_stack.c
@@ -310,7 +310,7 @@ void grpc_call_element_send_cancel_with_message(grpc_exec_ctx *exec_ctx,
   memset(op, 0, sizeof(*op));
   op->on_complete =
       grpc_closure_create(destroy_op, op, grpc_schedule_on_exec_ctx);
-  grpc_transport_stream_op_add_cancellation_with_message(op, status,
+  grpc_transport_stream_op_add_cancellation_with_message(exec_ctx, op, status,
                                                          optional_message);
   elem->filter->start_transport_stream_op(exec_ctx, elem, op);
 }
@@ -323,6 +323,6 @@ void grpc_call_element_send_close_with_message(grpc_exec_ctx *exec_ctx,
   memset(op, 0, sizeof(*op));
   op->on_complete =
       grpc_closure_create(destroy_op, op, grpc_schedule_on_exec_ctx);
-  grpc_transport_stream_op_add_close(op, status, optional_message);
+  grpc_transport_stream_op_add_close(exec_ctx, op, status, optional_message);
   elem->filter->start_transport_stream_op(exec_ctx, elem, op);
 }
diff --git a/src/core/lib/channel/channel_stack_builder.c b/src/core/lib/channel/channel_stack_builder.c
index b959517afb..5f9e3b4539 100644
--- a/src/core/lib/channel/channel_stack_builder.c
+++ b/src/core/lib/channel/channel_stack_builder.c
@@ -138,9 +138,10 @@ void grpc_channel_stack_builder_set_name(grpc_channel_stack_builder *builder,
 }
 
 void grpc_channel_stack_builder_set_channel_arguments(
-    grpc_channel_stack_builder *builder, const grpc_channel_args *args) {
+    grpc_exec_ctx *exec_ctx, grpc_channel_stack_builder *builder,
+    const grpc_channel_args *args) {
   if (builder->args != NULL) {
-    grpc_channel_args_destroy(builder->args);
+    grpc_channel_args_destroy(exec_ctx, builder->args);
   }
   builder->args = grpc_channel_args_copy(args);
 }
@@ -213,7 +214,8 @@ bool grpc_channel_stack_builder_add_filter_after(
   return true;
 }
 
-void grpc_channel_stack_builder_destroy(grpc_channel_stack_builder *builder) {
+void grpc_channel_stack_builder_destroy(grpc_exec_ctx *exec_ctx,
+                                        grpc_channel_stack_builder *builder) {
   filter_node *p = builder->begin.next;
   while (p != &builder->end) {
     filter_node *next = p->next;
@@ -221,7 +223,7 @@ void grpc_channel_stack_builder_destroy(grpc_channel_stack_builder *builder) {
     p = next;
   }
   if (builder->args != NULL) {
-    grpc_channel_args_destroy(builder->args);
+    grpc_channel_args_destroy(exec_ctx, builder->args);
   }
   gpr_free(builder->target);
   gpr_free(builder);
@@ -276,7 +278,7 @@ grpc_error *grpc_channel_stack_builder_finish(
     }
   }
 
-  grpc_channel_stack_builder_destroy(builder);
+  grpc_channel_stack_builder_destroy(exec_ctx, builder);
   gpr_free((grpc_channel_filter **)filters);
 
   return error;
diff --git a/src/core/lib/channel/channel_stack_builder.h b/src/core/lib/channel/channel_stack_builder.h
index 65bfebcabc..8adf38e27b 100644
--- a/src/core/lib/channel/channel_stack_builder.h
+++ b/src/core/lib/channel/channel_stack_builder.h
@@ -73,7 +73,8 @@ grpc_transport *grpc_channel_stack_builder_get_transport(
 
 /// Set channel arguments: copies args
 void grpc_channel_stack_builder_set_channel_arguments(
-    grpc_channel_stack_builder *builder, const grpc_channel_args *args);
+    grpc_exec_ctx *exec_ctx, grpc_channel_stack_builder *builder,
+    const grpc_channel_args *args);
 
 /// Return a borrowed pointer to the channel arguments
 const grpc_channel_args *grpc_channel_stack_builder_get_channel_arguments(
@@ -157,7 +158,8 @@ grpc_error *grpc_channel_stack_builder_finish(
     void *destroy_arg, void **result);
 
 /// Destroy the builder without creating a channel stack
-void grpc_channel_stack_builder_destroy(grpc_channel_stack_builder *builder);
+void grpc_channel_stack_builder_destroy(grpc_exec_ctx *exec_ctx,
+                                        grpc_channel_stack_builder *builder);
 
 extern int grpc_trace_channel_stack_builder;
 
diff --git a/src/core/lib/channel/compress_filter.c b/src/core/lib/channel/compress_filter.c
index 35455d4908..337c194b79 100644
--- a/src/core/lib/channel/compress_filter.c
+++ b/src/core/lib/channel/compress_filter.c
@@ -44,6 +44,7 @@
 #include "src/core/lib/compression/algorithm_metadata.h"
 #include "src/core/lib/compression/message_compress.h"
 #include "src/core/lib/profiling/timers.h"
+#include "src/core/lib/slice/slice_internal.h"
 #include "src/core/lib/support/string.h"
 #include "src/core/lib/transport/static_metadata.h"
 
@@ -82,7 +83,8 @@ typedef struct channel_data {
 /** For each \a md element from the incoming metadata, filter out the entry for
  * "grpc-encoding", using its value to populate the call data's
  * compression_algorithm field. */
-static grpc_mdelem *compression_md_filter(void *user_data, grpc_mdelem *md) {
+static grpc_mdelem *compression_md_filter(grpc_exec_ctx *exec_ctx,
+                                          void *user_data, grpc_mdelem *md) {
   grpc_call_element *elem = user_data;
   call_data *calld = elem->call_data;
   channel_data *channeld = elem->channel_data;
@@ -130,12 +132,14 @@ static int skip_compression(grpc_call_element *elem, uint32_t flags) {
 
 /** Filter initial metadata */
 static void process_send_initial_metadata(
-    grpc_call_element *elem, grpc_metadata_batch *initial_metadata) {
+    grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
+    grpc_metadata_batch *initial_metadata) {
   call_data *calld = elem->call_data;
   channel_data *channeld = elem->channel_data;
   /* Parse incoming request for compression. If any, it'll be available
    * at calld->compression_algorithm */
-  grpc_metadata_batch_filter(initial_metadata, compression_md_filter, elem);
+  grpc_metadata_batch_filter(exec_ctx, initial_metadata, compression_md_filter,
+                             elem);
   if (!calld->has_compression_algorithm) {
     /* If no algorithm was found in the metadata and we aren't
      * exceptionally skipping compression, fall back to the channel
@@ -161,7 +165,7 @@ static void continue_send_message(grpc_exec_ctx *exec_ctx,
 static void send_done(grpc_exec_ctx *exec_ctx, void *elemp, grpc_error *error) {
   grpc_call_element *elem = elemp;
   call_data *calld = elem->call_data;
-  grpc_slice_buffer_reset_and_unref(&calld->slices);
+  grpc_slice_buffer_reset_and_unref_internal(exec_ctx, &calld->slices);
   calld->post_send->cb(exec_ctx, calld->post_send->cb_arg, error);
 }
 
@@ -171,8 +175,8 @@ static void finish_send_message(grpc_exec_ctx *exec_ctx,
   int did_compress;
   grpc_slice_buffer tmp;
   grpc_slice_buffer_init(&tmp);
-  did_compress =
-      grpc_msg_compress(calld->compression_algorithm, &calld->slices, &tmp);
+  did_compress = grpc_msg_compress(exec_ctx, calld->compression_algorithm,
+                                   &calld->slices, &tmp);
   if (did_compress) {
     if (grpc_compression_trace) {
       char *algo_name;
@@ -199,7 +203,7 @@ static void finish_send_message(grpc_exec_ctx *exec_ctx,
     }
   }
 
-  grpc_slice_buffer_destroy(&tmp);
+  grpc_slice_buffer_destroy_internal(exec_ctx, &tmp);
 
   grpc_slice_buffer_stream_init(&calld->replacement_stream, &calld->slices,
                                 calld->send_flags);
@@ -243,7 +247,7 @@ static void compress_start_transport_stream_op(grpc_exec_ctx *exec_ctx,
   GPR_TIMER_BEGIN("compress_start_transport_stream_op", 0);
 
   if (op->send_initial_metadata) {
-    process_send_initial_metadata(elem, op->send_initial_metadata);
+    process_send_initial_metadata(exec_ctx, elem, op->send_initial_metadata);
   }
   if (op->send_message != NULL &&
       !skip_compression(elem, op->send_message->flags)) {
@@ -283,7 +287,7 @@ static void destroy_call_elem(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
                               void *ignored) {
   /* grab pointers to our data from the call element */
   call_data *calld = elem->call_data;
-  grpc_slice_buffer_destroy(&calld->slices);
+  grpc_slice_buffer_destroy_internal(exec_ctx, &calld->slices);
 }
 
 /* Constructor for channel_data */
diff --git a/src/core/lib/channel/connected_channel.c b/src/core/lib/channel/connected_channel.c
index c2a36b5558..ccc0619e1c 100644
--- a/src/core/lib/channel/connected_channel.c
+++ b/src/core/lib/channel/connected_channel.c
@@ -171,7 +171,8 @@ static void bind_transport(grpc_channel_stack *channel_stack,
   channel_stack->call_stack_size += grpc_transport_stream_size(t);
 }
 
-bool grpc_add_connected_filter(grpc_channel_stack_builder *builder,
+bool grpc_add_connected_filter(grpc_exec_ctx *exec_ctx,
+                               grpc_channel_stack_builder *builder,
                                void *arg_must_be_null) {
   GPR_ASSERT(arg_must_be_null == NULL);
   grpc_transport *t = grpc_channel_stack_builder_get_transport(builder);
diff --git a/src/core/lib/channel/connected_channel.h b/src/core/lib/channel/connected_channel.h
index 3142d647b7..3585c0ecbc 100644
--- a/src/core/lib/channel/connected_channel.h
+++ b/src/core/lib/channel/connected_channel.h
@@ -36,7 +36,8 @@
 
 #include "src/core/lib/channel/channel_stack_builder.h"
 
-bool grpc_add_connected_filter(grpc_channel_stack_builder *builder,
+bool grpc_add_connected_filter(grpc_exec_ctx *exec_ctx,
+                               grpc_channel_stack_builder *builder,
                                void *arg_must_be_null);
 
 #endif /* GRPC_CORE_LIB_CHANNEL_CONNECTED_CHANNEL_H */
diff --git a/src/core/lib/channel/deadline_filter.c b/src/core/lib/channel/deadline_filter.c
index 902ebf1955..a45a4d4b82 100644
--- a/src/core/lib/channel/deadline_filter.c
+++ b/src/core/lib/channel/deadline_filter.c
@@ -41,6 +41,7 @@
 
 #include "src/core/lib/iomgr/exec_ctx.h"
 #include "src/core/lib/iomgr/timer.h"
+#include "src/core/lib/slice/slice_internal.h"
 
 //
 // grpc_deadline_state
@@ -58,7 +59,7 @@ static void timer_callback(grpc_exec_ctx* exec_ctx, void* arg,
     grpc_slice msg = grpc_slice_from_static_string("Deadline Exceeded");
     grpc_call_element_send_cancel_with_message(
         exec_ctx, elem, GRPC_STATUS_DEADLINE_EXCEEDED, &msg);
-    grpc_slice_unref(msg);
+    grpc_slice_unref_internal(exec_ctx, msg);
   }
   GRPC_CALL_STACK_UNREF(exec_ctx, deadline_state->call_stack, "deadline_timer");
 }
@@ -82,8 +83,11 @@ static void start_timer_if_needed_locked(grpc_exec_ctx* exec_ctx,
     // Take a reference to the call stack, to be owned by the timer.
     GRPC_CALL_STACK_REF(deadline_state->call_stack, "deadline_timer");
     deadline_state->timer_pending = true;
-    grpc_timer_init(exec_ctx, &deadline_state->timer, deadline, timer_callback,
-                    elem, gpr_now(GPR_CLOCK_MONOTONIC));
+    grpc_closure_init(&deadline_state->timer_callback, timer_callback, elem,
+                      grpc_schedule_on_exec_ctx);
+    grpc_timer_init(exec_ctx, &deadline_state->timer, deadline,
+                    &deadline_state->timer_callback,
+                    gpr_now(GPR_CLOCK_MONOTONIC));
   }
 }
 static void start_timer_if_needed(grpc_exec_ctx* exec_ctx,
diff --git a/src/core/lib/channel/deadline_filter.h b/src/core/lib/channel/deadline_filter.h
index 716a852565..bd2b84f79e 100644
--- a/src/core/lib/channel/deadline_filter.h
+++ b/src/core/lib/channel/deadline_filter.h
@@ -46,6 +46,7 @@ typedef struct grpc_deadline_state {
   bool timer_pending;
   // The deadline timer.
   grpc_timer timer;
+  grpc_closure timer_callback;
   // Closure to invoke when the call is complete.
   // We use this to cancel the timer.
   grpc_closure on_complete;
diff --git a/src/core/lib/channel/handshaker.c b/src/core/lib/channel/handshaker.c
index ff827527b3..c052ca5385 100644
--- a/src/core/lib/channel/handshaker.c
+++ b/src/core/lib/channel/handshaker.c
@@ -86,6 +86,7 @@ struct grpc_handshake_manager {
   grpc_tcp_server_acceptor* acceptor;
   // Deadline timer across all handshakers.
   grpc_timer deadline_timer;
+  grpc_closure on_timeout;
   // The final callback and user_data to invoke after the last handshaker.
   grpc_closure on_handshake_done;
   void* user_data;
@@ -224,9 +225,11 @@ void grpc_handshake_manager_do_handshake(
                     grpc_schedule_on_exec_ctx);
   // Start deadline timer, which owns a ref.
   gpr_ref(&mgr->refs);
+  grpc_closure_init(&mgr->on_timeout, on_timeout, mgr,
+                    grpc_schedule_on_exec_ctx);
   grpc_timer_init(exec_ctx, &mgr->deadline_timer,
                   gpr_convert_clock_type(deadline, GPR_CLOCK_MONOTONIC),
-                  on_timeout, mgr, gpr_now(GPR_CLOCK_MONOTONIC));
+                  &mgr->on_timeout, gpr_now(GPR_CLOCK_MONOTONIC));
   // Start first handshaker, which also owns a ref.
   gpr_ref(&mgr->refs);
   bool done = call_next_handshaker_locked(exec_ctx, mgr, GRPC_ERROR_NONE);
diff --git a/src/core/lib/channel/handshaker_factory.c b/src/core/lib/channel/handshaker_factory.c
new file mode 100644
index 0000000000..3c30a4e1d2
--- /dev/null
+++ b/src/core/lib/channel/handshaker_factory.c
@@ -0,0 +1,54 @@
+/*
+ *
+ * Copyright 2016, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#include "src/core/lib/channel/handshaker_factory.h"
+
+#include <grpc/support/log.h>
+
+void grpc_handshaker_factory_add_handshakers(
+    grpc_exec_ctx *exec_ctx, grpc_handshaker_factory *handshaker_factory,
+    const grpc_channel_args *args, grpc_handshake_manager *handshake_mgr) {
+  if (handshaker_factory != NULL) {
+    GPR_ASSERT(handshaker_factory->vtable != NULL);
+    handshaker_factory->vtable->add_handshakers(exec_ctx, handshaker_factory,
+                                                args, handshake_mgr);
+  }
+}
+
+void grpc_handshaker_factory_destroy(
+    grpc_exec_ctx *exec_ctx, grpc_handshaker_factory *handshaker_factory) {
+  if (handshaker_factory != NULL) {
+    GPR_ASSERT(handshaker_factory->vtable != NULL);
+    handshaker_factory->vtable->destroy(exec_ctx, handshaker_factory);
+  }
+}
diff --git a/src/core/lib/channel/handshaker_factory.h b/src/core/lib/channel/handshaker_factory.h
new file mode 100644
index 0000000000..1984546104
--- /dev/null
+++ b/src/core/lib/channel/handshaker_factory.h
@@ -0,0 +1,66 @@
+/*
+ *
+ * Copyright 2016, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#ifndef GRPC_CORE_LIB_CHANNEL_HANDSHAKER_FACTORY_H
+#define GRPC_CORE_LIB_CHANNEL_HANDSHAKER_FACTORY_H
+
+#include <grpc/impl/codegen/grpc_types.h>
+
+#include "src/core/lib/channel/handshaker.h"
+#include "src/core/lib/iomgr/exec_ctx.h"
+
+// A handshaker factory is used to create handshakers.
+
+typedef struct grpc_handshaker_factory grpc_handshaker_factory;
+
+typedef struct {
+  void (*add_handshakers)(grpc_exec_ctx *exec_ctx,
+                          grpc_handshaker_factory *handshaker_factory,
+                          const grpc_channel_args *args,
+                          grpc_handshake_manager *handshake_mgr);
+  void (*destroy)(grpc_exec_ctx *exec_ctx,
+                  grpc_handshaker_factory *handshaker_factory);
+} grpc_handshaker_factory_vtable;
+
+struct grpc_handshaker_factory {
+  const grpc_handshaker_factory_vtable *vtable;
+};
+
+void grpc_handshaker_factory_add_handshakers(
+    grpc_exec_ctx *exec_ctx, grpc_handshaker_factory *handshaker_factory,
+    const grpc_channel_args *args, grpc_handshake_manager *handshake_mgr);
+
+void grpc_handshaker_factory_destroy(
+    grpc_exec_ctx *exec_ctx, grpc_handshaker_factory *handshaker_factory);
+
+#endif /* GRPC_CORE_LIB_CHANNEL_HANDSHAKER_FACTORY_H */
diff --git a/src/core/lib/channel/handshaker_registry.c b/src/core/lib/channel/handshaker_registry.c
new file mode 100644
index 0000000000..2e5f04064c
--- /dev/null
+++ b/src/core/lib/channel/handshaker_registry.c
@@ -0,0 +1,113 @@
+/*
+ *
+ * Copyright 2016, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#include "src/core/lib/channel/handshaker_registry.h"
+
+#include <string.h>
+
+#include <grpc/support/alloc.h>
+
+//
+// grpc_handshaker_factory_list
+//
+
+typedef struct {
+  grpc_handshaker_factory** list;
+  size_t num_factories;
+} grpc_handshaker_factory_list;
+
+static void grpc_handshaker_factory_list_register(
+    grpc_handshaker_factory_list* list, bool at_start,
+    grpc_handshaker_factory* factory) {
+  list->list = gpr_realloc(
+      list->list, (list->num_factories + 1) * sizeof(grpc_handshaker_factory*));
+  if (at_start) {
+    memmove(list->list + 1, list->list,
+            sizeof(grpc_handshaker_factory*) * list->num_factories);
+    list->list[0] = factory;
+  } else {
+    list->list[list->num_factories] = factory;
+  }
+  ++list->num_factories;
+}
+
+static void grpc_handshaker_factory_list_add_handshakers(
+    grpc_exec_ctx* exec_ctx, grpc_handshaker_factory_list* list,
+    const grpc_channel_args* args, grpc_handshake_manager* handshake_mgr) {
+  for (size_t i = 0; i < list->num_factories; ++i) {
+    grpc_handshaker_factory_add_handshakers(exec_ctx, list->list[i], args,
+                                            handshake_mgr);
+  }
+}
+
+static void grpc_handshaker_factory_list_destroy(
+    grpc_exec_ctx* exec_ctx, grpc_handshaker_factory_list* list) {
+  for (size_t i = 0; i < list->num_factories; ++i) {
+    grpc_handshaker_factory_destroy(exec_ctx, list->list[i]);
+  }
+  gpr_free(list->list);
+}
+
+//
+// plugin
+//
+
+static grpc_handshaker_factory_list
+    g_handshaker_factory_lists[NUM_HANDSHAKER_TYPES];
+
+void grpc_handshaker_factory_registry_init() {
+  memset(g_handshaker_factory_lists, 0, sizeof(g_handshaker_factory_lists));
+}
+
+void grpc_handshaker_factory_registry_shutdown(grpc_exec_ctx* exec_ctx) {
+  for (size_t i = 0; i < NUM_HANDSHAKER_TYPES; ++i) {
+    grpc_handshaker_factory_list_destroy(exec_ctx,
+                                         &g_handshaker_factory_lists[i]);
+  }
+}
+
+void grpc_handshaker_factory_register(bool at_start,
+                                      grpc_handshaker_type handshaker_type,
+                                      grpc_handshaker_factory* factory) {
+  grpc_handshaker_factory_list_register(
+      &g_handshaker_factory_lists[handshaker_type], at_start, factory);
+}
+
+void grpc_handshakers_add(grpc_exec_ctx* exec_ctx,
+                          grpc_handshaker_type handshaker_type,
+                          const grpc_channel_args* args,
+                          grpc_handshake_manager* handshake_mgr) {
+  grpc_handshaker_factory_list_add_handshakers(
+      exec_ctx, &g_handshaker_factory_lists[handshaker_type], args,
+      handshake_mgr);
+}
diff --git a/src/core/lib/channel/handshaker_registry.h b/src/core/lib/channel/handshaker_registry.h
new file mode 100644
index 0000000000..53c1b173af
--- /dev/null
+++ b/src/core/lib/channel/handshaker_registry.h
@@ -0,0 +1,63 @@
+/*
+ *
+ * Copyright 2016, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#ifndef GRPC_CORE_LIB_CHANNEL_HANDSHAKER_REGISTRY_H
+#define GRPC_CORE_LIB_CHANNEL_HANDSHAKER_REGISTRY_H
+
+#include <grpc/impl/codegen/grpc_types.h>
+
+#include "src/core/lib/channel/handshaker_factory.h"
+#include "src/core/lib/iomgr/exec_ctx.h"
+
+typedef enum {
+  HANDSHAKER_CLIENT = 0,
+  HANDSHAKER_SERVER,
+  NUM_HANDSHAKER_TYPES,  // Must be last.
+} grpc_handshaker_type;
+
+void grpc_handshaker_factory_registry_init();
+void grpc_handshaker_factory_registry_shutdown(grpc_exec_ctx* exec_ctx);
+
+/// Registers a new handshaker factory.  Takes ownership.
+/// If \a at_start is true, the new handshaker will be at the beginning of
+/// the list.  Otherwise, it will be added to the end.
+void grpc_handshaker_factory_register(bool at_start,
+                                      grpc_handshaker_type handshaker_type,
+                                      grpc_handshaker_factory* factory);
+
+void grpc_handshakers_add(grpc_exec_ctx* exec_ctx,
+                          grpc_handshaker_type handshaker_type,
+                          const grpc_channel_args* args,
+                          grpc_handshake_manager* handshake_mgr);
+
+#endif /* GRPC_CORE_LIB_CHANNEL_HANDSHAKER_REGISTRY_H */
diff --git a/src/core/lib/channel/http_client_filter.c b/src/core/lib/channel/http_client_filter.c
index c37cab3939..d154450988 100644
--- a/src/core/lib/channel/http_client_filter.c
+++ b/src/core/lib/channel/http_client_filter.c
@@ -37,6 +37,7 @@
 #include <string.h>
 #include "src/core/lib/profiling/timers.h"
 #include "src/core/lib/slice/percent_encoding.h"
+#include "src/core/lib/slice/slice_internal.h"
 #include "src/core/lib/support/string.h"
 #include "src/core/lib/transport/static_metadata.h"
 #include "src/core/lib/transport/transport_impl.h"
@@ -92,13 +93,9 @@ typedef struct channel_data {
   size_t max_payload_size_for_get;
 } channel_data;
 
-typedef struct {
-  grpc_call_element *elem;
-  grpc_exec_ctx *exec_ctx;
-} client_recv_filter_args;
-
-static grpc_mdelem *client_recv_filter(void *user_data, grpc_mdelem *md) {
-  client_recv_filter_args *a = user_data;
+static grpc_mdelem *client_recv_filter(grpc_exec_ctx *exec_ctx, void *user_data,
+                                       grpc_mdelem *md) {
+  grpc_call_element *elem = user_data;
   if (md == GRPC_MDELEM_STATUS_200) {
     return NULL;
   } else if (md->key == GRPC_MDSTR_STATUS) {
@@ -107,18 +104,19 @@ static grpc_mdelem *client_recv_filter(void *user_data, grpc_mdelem *md) {
                  grpc_mdstr_as_c_string(md->value));
     grpc_slice message = grpc_slice_from_copied_string(message_string);
     gpr_free(message_string);
-    grpc_call_element_send_close_with_message(a->exec_ctx, a->elem,
+    grpc_call_element_send_close_with_message(exec_ctx, elem,
                                               GRPC_STATUS_CANCELLED, &message);
     return NULL;
   } else if (md->key == GRPC_MDSTR_GRPC_MESSAGE) {
     grpc_slice pct_decoded_msg =
         grpc_permissive_percent_decode_slice(md->value->slice);
     if (grpc_slice_is_equivalent(pct_decoded_msg, md->value->slice)) {
-      grpc_slice_unref(pct_decoded_msg);
+      grpc_slice_unref_internal(exec_ctx, pct_decoded_msg);
       return md;
     } else {
       return grpc_mdelem_from_metadata_strings(
-          GRPC_MDSTR_GRPC_MESSAGE, grpc_mdstr_from_slice(pct_decoded_msg));
+          exec_ctx, GRPC_MDSTR_GRPC_MESSAGE,
+          grpc_mdstr_from_slice(exec_ctx, pct_decoded_msg));
     }
   } else if (md == GRPC_MDELEM_CONTENT_TYPE_APPLICATION_SLASH_GRPC) {
     return NULL;
@@ -147,11 +145,8 @@ static void hc_on_recv_initial_metadata(grpc_exec_ctx *exec_ctx,
                                         void *user_data, grpc_error *error) {
   grpc_call_element *elem = user_data;
   call_data *calld = elem->call_data;
-  client_recv_filter_args a;
-  a.elem = elem;
-  a.exec_ctx = exec_ctx;
-  grpc_metadata_batch_filter(calld->recv_initial_metadata, client_recv_filter,
-                             &a);
+  grpc_metadata_batch_filter(exec_ctx, calld->recv_initial_metadata,
+                             client_recv_filter, elem);
   grpc_closure_run(exec_ctx, calld->on_done_recv_initial_metadata,
                    GRPC_ERROR_REF(error));
 }
@@ -160,11 +155,8 @@ static void hc_on_recv_trailing_metadata(grpc_exec_ctx *exec_ctx,
                                          void *user_data, grpc_error *error) {
   grpc_call_element *elem = user_data;
   call_data *calld = elem->call_data;
-  client_recv_filter_args a;
-  a.elem = elem;
-  a.exec_ctx = exec_ctx;
-  grpc_metadata_batch_filter(calld->recv_trailing_metadata, client_recv_filter,
-                             &a);
+  grpc_metadata_batch_filter(exec_ctx, calld->recv_trailing_metadata,
+                             client_recv_filter, elem);
   grpc_closure_run(exec_ctx, calld->on_done_recv_trailing_metadata,
                    GRPC_ERROR_REF(error));
 }
@@ -183,11 +175,12 @@ static void hc_on_complete(grpc_exec_ctx *exec_ctx, void *user_data,
 static void send_done(grpc_exec_ctx *exec_ctx, void *elemp, grpc_error *error) {
   grpc_call_element *elem = elemp;
   call_data *calld = elem->call_data;
-  grpc_slice_buffer_reset_and_unref(&calld->slices);
+  grpc_slice_buffer_reset_and_unref_internal(exec_ctx, &calld->slices);
   calld->post_send->cb(exec_ctx, calld->post_send->cb_arg, error);
 }
 
-static grpc_mdelem *client_strip_filter(void *user_data, grpc_mdelem *md) {
+static grpc_mdelem *client_strip_filter(grpc_exec_ctx *exec_ctx,
+                                        void *user_data, grpc_mdelem *md) {
   /* eat the things we'd like to set ourselves */
   if (md->key == GRPC_MDSTR_METHOD) return NULL;
   if (md->key == GRPC_MDSTR_SCHEME) return NULL;
@@ -275,7 +268,7 @@ static void hc_mutate_op(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
         /* when all the send_message data is available, then create a MDELEM and
         append to headers */
         grpc_mdelem *payload_bin = grpc_mdelem_from_metadata_strings(
-            GRPC_MDSTR_GRPC_PAYLOAD_BIN,
+            exec_ctx, GRPC_MDSTR_GRPC_PAYLOAD_BIN,
             grpc_mdstr_from_buffer(calld->payload_bytes,
                                    op->send_message->length));
         grpc_metadata_batch_add_tail(op->send_initial_metadata,
@@ -292,8 +285,8 @@ static void hc_mutate_op(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
       }
     }
 
-    grpc_metadata_batch_filter(op->send_initial_metadata, client_strip_filter,
-                               elem);
+    grpc_metadata_batch_filter(exec_ctx, op->send_initial_metadata,
+                               client_strip_filter, elem);
     /* Send : prefixed headers, which have to be before any application
        layer headers. */
     grpc_metadata_batch_add_head(op->send_initial_metadata, &calld->method,
@@ -371,7 +364,7 @@ static void destroy_call_elem(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
                               const grpc_call_final_info *final_info,
                               void *ignored) {
   call_data *calld = elem->call_data;
-  grpc_slice_buffer_destroy(&calld->slices);
+  grpc_slice_buffer_destroy_internal(exec_ctx, &calld->slices);
 }
 
 static grpc_mdelem *scheme_from_args(const grpc_channel_args *args) {
@@ -472,7 +465,7 @@ static grpc_error *init_channel_elem(grpc_exec_ctx *exec_ctx,
   chand->max_payload_size_for_get =
       max_payload_size_from_args(args->channel_args);
   chand->user_agent = grpc_mdelem_from_metadata_strings(
-      GRPC_MDSTR_USER_AGENT,
+      exec_ctx, GRPC_MDSTR_USER_AGENT,
       user_agent_from_args(args->channel_args,
                            args->optional_transport->vtable->name));
   return GRPC_ERROR_NONE;
@@ -482,7 +475,7 @@ static grpc_error *init_channel_elem(grpc_exec_ctx *exec_ctx,
 static void destroy_channel_elem(grpc_exec_ctx *exec_ctx,
                                  grpc_channel_element *elem) {
   channel_data *chand = elem->channel_data;
-  GRPC_MDELEM_UNREF(chand->user_agent);
+  GRPC_MDELEM_UNREF(exec_ctx, chand->user_agent);
 }
 
 const grpc_channel_filter grpc_http_client_filter = {
diff --git a/src/core/lib/channel/http_server_filter.c b/src/core/lib/channel/http_server_filter.c
index a6d720530a..f508231238 100644
--- a/src/core/lib/channel/http_server_filter.c
+++ b/src/core/lib/channel/http_server_filter.c
@@ -38,6 +38,7 @@
 #include <string.h>
 #include "src/core/lib/profiling/timers.h"
 #include "src/core/lib/slice/percent_encoding.h"
+#include "src/core/lib/slice/slice_internal.h"
 #include "src/core/lib/transport/static_metadata.h"
 
 #define EXPECTED_CONTENT_TYPE "application/grpc"
@@ -82,31 +83,28 @@ typedef struct call_data {
 
 typedef struct channel_data { uint8_t unused; } channel_data;
 
-typedef struct {
-  grpc_call_element *elem;
-  grpc_exec_ctx *exec_ctx;
-} server_filter_args;
-
-static grpc_mdelem *server_filter_outgoing_metadata(void *user_data,
+static grpc_mdelem *server_filter_outgoing_metadata(grpc_exec_ctx *exec_ctx,
+                                                    void *user_data,
                                                     grpc_mdelem *md) {
   if (md->key == GRPC_MDSTR_GRPC_MESSAGE) {
     grpc_slice pct_encoded_msg = grpc_percent_encode_slice(
         md->value->slice, grpc_compatible_percent_encoding_unreserved_bytes);
     if (grpc_slice_is_equivalent(pct_encoded_msg, md->value->slice)) {
-      grpc_slice_unref(pct_encoded_msg);
+      grpc_slice_unref_internal(exec_ctx, pct_encoded_msg);
       return md;
     } else {
       return grpc_mdelem_from_metadata_strings(
-          GRPC_MDSTR_GRPC_MESSAGE, grpc_mdstr_from_slice(pct_encoded_msg));
+          exec_ctx, GRPC_MDSTR_GRPC_MESSAGE,
+          grpc_mdstr_from_slice(exec_ctx, pct_encoded_msg));
     }
   } else {
     return md;
   }
 }
 
-static grpc_mdelem *server_filter(void *user_data, grpc_mdelem *md) {
-  server_filter_args *a = user_data;
-  grpc_call_element *elem = a->elem;
+static grpc_mdelem *server_filter(grpc_exec_ctx *exec_ctx, void *user_data,
+                                  grpc_mdelem *md) {
+  grpc_call_element *elem = user_data;
   call_data *calld = elem->call_data;
 
   /* Check if it is one of the headers we care about. */
@@ -157,7 +155,7 @@ static grpc_mdelem *server_filter(void *user_data, grpc_mdelem *md) {
     /* swallow it and error everything out. */
     /* TODO(klempner): We ought to generate more descriptive error messages
        on the wire here. */
-    grpc_call_element_send_cancel(a->exec_ctx, elem);
+    grpc_call_element_send_cancel(exec_ctx, elem);
     return NULL;
   } else if (md->key == GRPC_MDSTR_PATH) {
     if (calld->seen_path) {
@@ -173,7 +171,7 @@ static grpc_mdelem *server_filter(void *user_data, grpc_mdelem *md) {
     /* translate host to :authority since :authority may be
        omitted */
     grpc_mdelem *authority = grpc_mdelem_from_metadata_strings(
-        GRPC_MDSTR_AUTHORITY, GRPC_MDSTR_REF(md->value));
+        exec_ctx, GRPC_MDSTR_AUTHORITY, GRPC_MDSTR_REF(md->value));
     calld->seen_authority = 1;
     return authority;
   } else if (md->key == GRPC_MDSTR_GRPC_PAYLOAD_BIN) {
@@ -181,7 +179,7 @@ static grpc_mdelem *server_filter(void *user_data, grpc_mdelem *md) {
        header field */
     calld->seen_payload_bin = 1;
     grpc_slice_buffer_add(&calld->read_slice_buffer,
-                          grpc_slice_ref(md->value->slice));
+                          grpc_slice_ref_internal(md->value->slice));
     grpc_slice_buffer_stream_init(&calld->read_stream,
                                   &calld->read_slice_buffer, 0);
     return NULL;
@@ -195,10 +193,8 @@ static void hs_on_recv(grpc_exec_ctx *exec_ctx, void *user_data,
   grpc_call_element *elem = user_data;
   call_data *calld = elem->call_data;
   if (err == GRPC_ERROR_NONE) {
-    server_filter_args a;
-    a.elem = elem;
-    a.exec_ctx = exec_ctx;
-    grpc_metadata_batch_filter(calld->recv_initial_metadata, server_filter, &a);
+    grpc_metadata_batch_filter(exec_ctx, calld->recv_initial_metadata,
+                               server_filter, elem);
     /* Have we seen the required http2 transport headers?
        (:method, :scheme, content-type, with :path and :authority covered
        at the channel level right now) */
@@ -310,9 +306,8 @@ static void hs_mutate_op(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
   }
 
   if (op->send_trailing_metadata) {
-    server_filter_args a = {elem, exec_ctx};
-    grpc_metadata_batch_filter(op->send_trailing_metadata,
-                               server_filter_outgoing_metadata, &a);
+    grpc_metadata_batch_filter(exec_ctx, op->send_trailing_metadata,
+                               server_filter_outgoing_metadata, elem);
   }
 }
 
@@ -349,7 +344,7 @@ static void destroy_call_elem(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
                               const grpc_call_final_info *final_info,
                               void *ignored) {
   call_data *calld = elem->call_data;
-  grpc_slice_buffer_destroy(&calld->read_slice_buffer);
+  grpc_slice_buffer_destroy_internal(exec_ctx, &calld->read_slice_buffer);
 }
 
 /* Constructor for channel_data */
diff --git a/src/core/lib/channel/message_size_filter.c b/src/core/lib/channel/message_size_filter.c
index b5e882de52..862090b371 100644
--- a/src/core/lib/channel/message_size_filter.c
+++ b/src/core/lib/channel/message_size_filter.c
@@ -54,8 +54,12 @@ static void* message_size_limits_copy(void* value) {
   return new_value;
 }
 
+static void message_size_limits_free(grpc_exec_ctx* exec_ctx, void* value) {
+  gpr_free(value);
+}
+
 static const grpc_mdstr_hash_table_vtable message_size_limits_vtable = {
-    gpr_free, message_size_limits_copy};
+    message_size_limits_free, message_size_limits_copy};
 
 static void* message_size_limits_create_from_json(const grpc_json* json) {
   int max_request_message_bytes = -1;
@@ -169,8 +173,8 @@ static grpc_error* init_call_elem(grpc_exec_ctx* exec_ctx,
   calld->max_send_size = chand->max_send_size;
   calld->max_recv_size = chand->max_recv_size;
   if (chand->method_limit_table != NULL) {
-    message_size_limits* limits =
-        grpc_method_config_table_get(chand->method_limit_table, args->path);
+    message_size_limits* limits = grpc_method_config_table_get(
+        exec_ctx, chand->method_limit_table, args->path);
     if (limits != NULL) {
       if (limits->max_send_size >= 0 &&
           (limits->max_send_size < calld->max_send_size ||
@@ -227,7 +231,7 @@ static grpc_error* init_channel_elem(grpc_exec_ctx* exec_ctx,
     if (service_config != NULL) {
       chand->method_limit_table =
           grpc_service_config_create_method_config_table(
-              service_config, message_size_limits_create_from_json,
+              exec_ctx, service_config, message_size_limits_create_from_json,
               &message_size_limits_vtable);
       grpc_service_config_destroy(service_config);
     }
@@ -239,7 +243,7 @@ static grpc_error* init_channel_elem(grpc_exec_ctx* exec_ctx,
 static void destroy_channel_elem(grpc_exec_ctx* exec_ctx,
                                  grpc_channel_element* elem) {
   channel_data* chand = elem->channel_data;
-  grpc_mdstr_hash_table_unref(chand->method_limit_table);
+  grpc_mdstr_hash_table_unref(exec_ctx, chand->method_limit_table);
 }
 
 const grpc_channel_filter grpc_message_size_filter = {
diff --git a/src/core/lib/compression/message_compress.c b/src/core/lib/compression/message_compress.c
index 6c245acf61..49beb953b0 100644
--- a/src/core/lib/compression/message_compress.c
+++ b/src/core/lib/compression/message_compress.c
@@ -40,10 +40,12 @@
 
 #include <zlib.h>
 
+#include "src/core/lib/slice/slice_internal.h"
+
 #define OUTPUT_BLOCK_SIZE 1024
 
-static int zlib_body(z_stream* zs, grpc_slice_buffer* input,
-                     grpc_slice_buffer* output,
+static int zlib_body(grpc_exec_ctx* exec_ctx, z_stream* zs,
+                     grpc_slice_buffer* input, grpc_slice_buffer* output,
                      int (*flate)(z_stream* zs, int flush)) {
   int r;
   int flush;
@@ -87,7 +89,7 @@ static int zlib_body(z_stream* zs, grpc_slice_buffer* input,
   return 1;
 
 error:
-  grpc_slice_unref(outbuf);
+  grpc_slice_unref_internal(exec_ctx, outbuf);
   return 0;
 }
 
@@ -97,8 +99,8 @@ static void* zalloc_gpr(void* opaque, unsigned int items, unsigned int size) {
 
 static void zfree_gpr(void* opaque, void* address) { gpr_free(address); }
 
-static int zlib_compress(grpc_slice_buffer* input, grpc_slice_buffer* output,
-                         int gzip) {
+static int zlib_compress(grpc_exec_ctx* exec_ctx, grpc_slice_buffer* input,
+                         grpc_slice_buffer* output, int gzip) {
   z_stream zs;
   int r;
   size_t i;
@@ -110,10 +112,11 @@ static int zlib_compress(grpc_slice_buffer* input, grpc_slice_buffer* output,
   r = deflateInit2(&zs, Z_DEFAULT_COMPRESSION, Z_DEFLATED, 15 | (gzip ? 16 : 0),
                    8, Z_DEFAULT_STRATEGY);
   GPR_ASSERT(r == Z_OK);
-  r = zlib_body(&zs, input, output, deflate) && output->length < input->length;
+  r = zlib_body(exec_ctx, &zs, input, output, deflate) &&
+      output->length < input->length;
   if (!r) {
     for (i = count_before; i < output->count; i++) {
-      grpc_slice_unref(output->slices[i]);
+      grpc_slice_unref_internal(exec_ctx, output->slices[i]);
     }
     output->count = count_before;
     output->length = length_before;
@@ -122,8 +125,8 @@ static int zlib_compress(grpc_slice_buffer* input, grpc_slice_buffer* output,
   return r;
 }
 
-static int zlib_decompress(grpc_slice_buffer* input, grpc_slice_buffer* output,
-                           int gzip) {
+static int zlib_decompress(grpc_exec_ctx* exec_ctx, grpc_slice_buffer* input,
+                           grpc_slice_buffer* output, int gzip) {
   z_stream zs;
   int r;
   size_t i;
@@ -134,10 +137,10 @@ static int zlib_decompress(grpc_slice_buffer* input, grpc_slice_buffer* output,
   zs.zfree = zfree_gpr;
   r = inflateInit2(&zs, 15 | (gzip ? 16 : 0));
   GPR_ASSERT(r == Z_OK);
-  r = zlib_body(&zs, input, output, inflate);
+  r = zlib_body(exec_ctx, &zs, input, output, inflate);
   if (!r) {
     for (i = count_before; i < output->count; i++) {
-      grpc_slice_unref(output->slices[i]);
+      grpc_slice_unref_internal(exec_ctx, output->slices[i]);
     }
     output->count = count_before;
     output->length = length_before;
@@ -149,12 +152,13 @@ static int zlib_decompress(grpc_slice_buffer* input, grpc_slice_buffer* output,
 static int copy(grpc_slice_buffer* input, grpc_slice_buffer* output) {
   size_t i;
   for (i = 0; i < input->count; i++) {
-    grpc_slice_buffer_add(output, grpc_slice_ref(input->slices[i]));
+    grpc_slice_buffer_add(output, grpc_slice_ref_internal(input->slices[i]));
   }
   return 1;
 }
 
-static int compress_inner(grpc_compression_algorithm algorithm,
+static int compress_inner(grpc_exec_ctx* exec_ctx,
+                          grpc_compression_algorithm algorithm,
                           grpc_slice_buffer* input, grpc_slice_buffer* output) {
   switch (algorithm) {
     case GRPC_COMPRESS_NONE:
@@ -162,9 +166,9 @@ static int compress_inner(grpc_compression_algorithm algorithm,
          rely on that here */
       return 0;
     case GRPC_COMPRESS_DEFLATE:
-      return zlib_compress(input, output, 0);
+      return zlib_compress(exec_ctx, input, output, 0);
     case GRPC_COMPRESS_GZIP:
-      return zlib_compress(input, output, 1);
+      return zlib_compress(exec_ctx, input, output, 1);
     case GRPC_COMPRESS_ALGORITHMS_COUNT:
       break;
   }
@@ -172,24 +176,26 @@ static int compress_inner(grpc_compression_algorithm algorithm,
   return 0;
 }
 
-int grpc_msg_compress(grpc_compression_algorithm algorithm,
+int grpc_msg_compress(grpc_exec_ctx* exec_ctx,
+                      grpc_compression_algorithm algorithm,
                       grpc_slice_buffer* input, grpc_slice_buffer* output) {
-  if (!compress_inner(algorithm, input, output)) {
+  if (!compress_inner(exec_ctx, algorithm, input, output)) {
     copy(input, output);
     return 0;
   }
   return 1;
 }
 
-int grpc_msg_decompress(grpc_compression_algorithm algorithm,
+int grpc_msg_decompress(grpc_exec_ctx* exec_ctx,
+                        grpc_compression_algorithm algorithm,
                         grpc_slice_buffer* input, grpc_slice_buffer* output) {
   switch (algorithm) {
     case GRPC_COMPRESS_NONE:
       return copy(input, output);
     case GRPC_COMPRESS_DEFLATE:
-      return zlib_decompress(input, output, 0);
+      return zlib_decompress(exec_ctx, input, output, 0);
     case GRPC_COMPRESS_GZIP:
-      return zlib_decompress(input, output, 1);
+      return zlib_decompress(exec_ctx, input, output, 1);
     case GRPC_COMPRESS_ALGORITHMS_COUNT:
       break;
   }
diff --git a/src/core/lib/compression/message_compress.h b/src/core/lib/compression/message_compress.h
index 448d36a863..7bd3d98607 100644
--- a/src/core/lib/compression/message_compress.h
+++ b/src/core/lib/compression/message_compress.h
@@ -40,13 +40,15 @@
 /* compress 'input' to 'output' using 'algorithm'.
    On success, appends compressed slices to output and returns 1.
    On failure, appends uncompressed slices to output and returns 0. */
-int grpc_msg_compress(grpc_compression_algorithm algorithm,
+int grpc_msg_compress(grpc_exec_ctx* exec_ctx,
+                      grpc_compression_algorithm algorithm,
                       grpc_slice_buffer* input, grpc_slice_buffer* output);
 
 /* decompress 'input' to 'output' using 'algorithm'.
    On success, appends slices to output and returns 1.
    On failure, output is unchanged, and returns 0. */
-int grpc_msg_decompress(grpc_compression_algorithm algorithm,
+int grpc_msg_decompress(grpc_exec_ctx* exec_ctx,
+                        grpc_compression_algorithm algorithm,
                         grpc_slice_buffer* input, grpc_slice_buffer* output);
 
 #endif /* GRPC_CORE_LIB_COMPRESSION_MESSAGE_COMPRESS_H */
diff --git a/src/core/lib/http/httpcli.c b/src/core/lib/http/httpcli.c
index 581a74b73f..fb2108987b 100644
--- a/src/core/lib/http/httpcli.c
+++ b/src/core/lib/http/httpcli.c
@@ -47,6 +47,7 @@
 #include "src/core/lib/iomgr/resolve_address.h"
 #include "src/core/lib/iomgr/sockaddr_utils.h"
 #include "src/core/lib/iomgr/tcp_client.h"
+#include "src/core/lib/slice/slice_internal.h"
 #include "src/core/lib/support/string.h"
 
 typedef struct {
@@ -111,14 +112,14 @@ static void finish(grpc_exec_ctx *exec_ctx, internal_request *req,
   if (req->ep != NULL) {
     grpc_endpoint_destroy(exec_ctx, req->ep);
   }
-  grpc_slice_unref(req->request_text);
+  grpc_slice_unref_internal(exec_ctx, req->request_text);
   gpr_free(req->host);
   gpr_free(req->ssl_host_override);
   grpc_iomgr_unregister_object(&req->iomgr_obj);
-  grpc_slice_buffer_destroy(&req->incoming);
-  grpc_slice_buffer_destroy(&req->outgoing);
+  grpc_slice_buffer_destroy_internal(exec_ctx, &req->incoming);
+  grpc_slice_buffer_destroy_internal(exec_ctx, &req->outgoing);
   GRPC_ERROR_UNREF(req->overall_error);
-  grpc_resource_quota_internal_unref(exec_ctx, req->resource_quota);
+  grpc_resource_quota_unref_internal(exec_ctx, req->resource_quota);
   gpr_free(req);
 }
 
@@ -178,7 +179,7 @@ static void done_write(grpc_exec_ctx *exec_ctx, void *arg, grpc_error *error) {
 }
 
 static void start_write(grpc_exec_ctx *exec_ctx, internal_request *req) {
-  grpc_slice_ref(req->request_text);
+  grpc_slice_ref_internal(req->request_text);
   grpc_slice_buffer_add(&req->outgoing, req->request_text);
   grpc_endpoint_write(exec_ctx, req->ep, &req->outgoing, &req->done_write);
 }
@@ -266,7 +267,7 @@ static void internal_request_begin(grpc_exec_ctx *exec_ctx,
   req->context = context;
   req->pollent = pollent;
   req->overall_error = GRPC_ERROR_NONE;
-  req->resource_quota = grpc_resource_quota_internal_ref(resource_quota);
+  req->resource_quota = grpc_resource_quota_ref_internal(resource_quota);
   grpc_closure_init(&req->on_read, on_read, req, grpc_schedule_on_exec_ctx);
   grpc_closure_init(&req->done_write, done_write, req,
                     grpc_schedule_on_exec_ctx);
diff --git a/src/core/lib/http/httpcli_security_connector.c b/src/core/lib/http/httpcli_security_connector.c
index 6b197c2e35..440817c5a6 100644
--- a/src/core/lib/http/httpcli_security_connector.c
+++ b/src/core/lib/http/httpcli_security_connector.c
@@ -41,6 +41,7 @@
 
 #include "src/core/lib/channel/channel_args.h"
 #include "src/core/lib/security/transport/security_handshaker.h"
+#include "src/core/lib/slice/slice_internal.h"
 #include "src/core/lib/support/string.h"
 #include "src/core/lib/tsi/ssl_transport_security.h"
 
@@ -50,7 +51,8 @@ typedef struct {
   char *secure_peer_name;
 } grpc_httpcli_ssl_channel_security_connector;
 
-static void httpcli_ssl_destroy(grpc_security_connector *sc) {
+static void httpcli_ssl_destroy(grpc_exec_ctx *exec_ctx,
+                                grpc_security_connector *sc) {
   grpc_httpcli_ssl_channel_security_connector *c =
       (grpc_httpcli_ssl_channel_security_connector *)sc;
   if (c->handshaker_factory != NULL) {
@@ -104,8 +106,9 @@ static grpc_security_connector_vtable httpcli_ssl_vtable = {
     httpcli_ssl_destroy, httpcli_ssl_check_peer};
 
 static grpc_security_status httpcli_ssl_channel_security_connector_create(
-    const unsigned char *pem_root_certs, size_t pem_root_certs_size,
-    const char *secure_peer_name, grpc_channel_security_connector **sc) {
+    grpc_exec_ctx *exec_ctx, const unsigned char *pem_root_certs,
+    size_t pem_root_certs_size, const char *secure_peer_name,
+    grpc_channel_security_connector **sc) {
   tsi_result result = TSI_OK;
   grpc_httpcli_ssl_channel_security_connector *c;
 
@@ -129,7 +132,7 @@ static grpc_security_status httpcli_ssl_channel_security_connector_create(
   if (result != TSI_OK) {
     gpr_log(GPR_ERROR, "Handshaker factory creation failed with %s.",
             tsi_result_to_string(result));
-    httpcli_ssl_destroy(&c->base.base);
+    httpcli_ssl_destroy(exec_ctx, &c->base.base);
     *sc = NULL;
     return GRPC_SECURITY_ERROR;
   }
@@ -156,8 +159,8 @@ static void on_handshake_done(grpc_exec_ctx *exec_ctx, void *arg,
     grpc_error_free_string(msg);
     c->func(exec_ctx, c->arg, NULL);
   } else {
-    grpc_channel_args_destroy(args->args);
-    grpc_slice_buffer_destroy(args->read_buffer);
+    grpc_channel_args_destroy(exec_ctx, args->args);
+    grpc_slice_buffer_destroy_internal(exec_ctx, args->read_buffer);
     gpr_free(args->read_buffer);
     c->func(exec_ctx, c->arg, args->endpoint);
   }
@@ -184,14 +187,14 @@ static void ssl_handshake(grpc_exec_ctx *exec_ctx, void *arg,
   c->arg = arg;
   c->handshake_mgr = grpc_handshake_manager_create();
   GPR_ASSERT(httpcli_ssl_channel_security_connector_create(
-                 pem_root_certs, pem_root_certs_size, host, &sc) ==
+                 exec_ctx, pem_root_certs, pem_root_certs_size, host, &sc) ==
              GRPC_SECURITY_OK);
   grpc_channel_security_connector_add_handshakers(exec_ctx, sc,
                                                   c->handshake_mgr);
   grpc_handshake_manager_do_handshake(
       exec_ctx, c->handshake_mgr, tcp, NULL /* channel_args */, deadline,
       NULL /* acceptor */, on_handshake_done, c /* user_data */);
-  GRPC_SECURITY_CONNECTOR_UNREF(&sc->base, "httpcli");
+  GRPC_SECURITY_CONNECTOR_UNREF(exec_ctx, &sc->base, "httpcli");
 }
 
 const grpc_httpcli_handshaker grpc_httpcli_ssl = {"https", ssl_handshake};
diff --git a/src/core/lib/iomgr/README.md b/src/core/lib/iomgr/README.md
new file mode 100644
index 0000000000..9b22b76ceb
--- /dev/null
+++ b/src/core/lib/iomgr/README.md
@@ -0,0 +1,6 @@
+# iomgr
+
+Platform abstractions for I/O (mostly network).
+
+Provides abstractions over TCP/UDP I/O, file loading, polling, and concurrency
+management for various operating systems.
diff --git a/src/core/lib/iomgr/closure.h b/src/core/lib/iomgr/closure.h
index 1a4ebbd360..7ffec29ebb 100644
--- a/src/core/lib/iomgr/closure.h
+++ b/src/core/lib/iomgr/closure.h
@@ -35,6 +35,8 @@
 #define GRPC_CORE_LIB_IOMGR_CLOSURE_H
 
 #include <grpc/support/port_platform.h>
+
+#include <grpc/impl/codegen/exec_ctx_fwd.h>
 #include <stdbool.h>
 #include "src/core/lib/iomgr/error.h"
 #include "src/core/lib/support/mpscq.h"
@@ -42,10 +44,6 @@
 struct grpc_closure;
 typedef struct grpc_closure grpc_closure;
 
-/* forward declaration for exec_ctx.h */
-struct grpc_exec_ctx;
-typedef struct grpc_exec_ctx grpc_exec_ctx;
-
 typedef struct grpc_closure_list {
   grpc_closure *head;
   grpc_closure *tail;
diff --git a/src/core/lib/iomgr/ev_epoll_linux.c b/src/core/lib/iomgr/ev_epoll_linux.c
index 045001f6d8..d6664aead2 100644
--- a/src/core/lib/iomgr/ev_epoll_linux.c
+++ b/src/core/lib/iomgr/ev_epoll_linux.c
@@ -31,7 +31,6 @@
  *
  */
 
-#include <grpc/grpc_posix.h>
 #include "src/core/lib/iomgr/port.h"
 
 /* This polling engine is only relevant on linux kernels supporting epoll() */
diff --git a/src/core/lib/iomgr/executor.c b/src/core/lib/iomgr/executor.c
index 1342a28d8d..852775564f 100644
--- a/src/core/lib/iomgr/executor.c
+++ b/src/core/lib/iomgr/executor.c
@@ -130,9 +130,8 @@ static void executor_push(grpc_exec_ctx *exec_ctx, grpc_closure *closure,
   gpr_mu_unlock(&g_executor.mu);
 }
 
-void grpc_executor_shutdown() {
+void grpc_executor_shutdown(grpc_exec_ctx *exec_ctx) {
   int pending_join;
-  grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
 
   gpr_mu_lock(&g_executor.mu);
   pending_join = g_executor.pending_join;
@@ -147,11 +146,11 @@ void grpc_executor_shutdown() {
   while (c != NULL) {
     grpc_closure *next = c->next_data.next;
     grpc_error *error = c->error_data.error;
-    c->cb(&exec_ctx, c->cb_arg, error);
+    c->cb(exec_ctx, c->cb_arg, error);
     GRPC_ERROR_UNREF(error);
     c = next;
   }
-  grpc_exec_ctx_finish(&exec_ctx);
+  grpc_exec_ctx_flush(exec_ctx);
   GPR_ASSERT(grpc_closure_list_empty(g_executor.closures));
   if (pending_join) {
     gpr_thd_join(g_executor.tid);
diff --git a/src/core/lib/iomgr/executor.h b/src/core/lib/iomgr/executor.h
index 53f3b6d441..1213016383 100644
--- a/src/core/lib/iomgr/executor.h
+++ b/src/core/lib/iomgr/executor.h
@@ -46,6 +46,6 @@ void grpc_executor_init();
 extern grpc_closure_scheduler *grpc_executor_scheduler;
 
 /** Shutdown the executor, running all pending work as part of the call */
-void grpc_executor_shutdown();
+void grpc_executor_shutdown(grpc_exec_ctx *exec_ctx);
 
 #endif /* GRPC_CORE_LIB_IOMGR_EXECUTOR_H */
diff --git a/src/core/lib/iomgr/iocp_windows.c b/src/core/lib/iomgr/iocp_windows.c
index 60ebe43676..f0f4a6ff39 100644
--- a/src/core/lib/iomgr/iocp_windows.c
+++ b/src/core/lib/iomgr/iocp_windows.c
@@ -80,7 +80,6 @@ grpc_iocp_work_status grpc_iocp_work(grpc_exec_ctx *exec_ctx,
   LPOVERLAPPED overlapped;
   grpc_winsocket *socket;
   grpc_winsocket_callback_info *info;
-  grpc_closure *closure = NULL;
   success = GetQueuedCompletionStatus(
       g_iocp, &bytes, &completion_key, &overlapped,
       deadline_to_millis_timeout(deadline, gpr_now(deadline.clock_type)));
diff --git a/src/core/lib/iomgr/iomgr.c b/src/core/lib/iomgr/iomgr.c
index 3470b5ac81..001e528409 100644
--- a/src/core/lib/iomgr/iomgr.c
+++ b/src/core/lib/iomgr/iomgr.c
@@ -83,11 +83,10 @@ static void dump_objects(const char *kind) {
   }
 }
 
-void grpc_iomgr_shutdown(void) {
+void grpc_iomgr_shutdown(grpc_exec_ctx *exec_ctx) {
   gpr_timespec shutdown_deadline = gpr_time_add(
       gpr_now(GPR_CLOCK_REALTIME), gpr_time_from_seconds(10, GPR_TIMESPAN));
   gpr_timespec last_warning_time = gpr_now(GPR_CLOCK_REALTIME);
-  grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
 
   grpc_iomgr_platform_flush();
 
@@ -104,10 +103,9 @@ void grpc_iomgr_shutdown(void) {
       }
       last_warning_time = gpr_now(GPR_CLOCK_REALTIME);
     }
-    if (grpc_timer_check(&exec_ctx, gpr_inf_future(GPR_CLOCK_MONOTONIC),
-                         NULL)) {
+    if (grpc_timer_check(exec_ctx, gpr_inf_future(GPR_CLOCK_MONOTONIC), NULL)) {
       gpr_mu_unlock(&g_mu);
-      grpc_exec_ctx_flush(&exec_ctx);
+      grpc_exec_ctx_flush(exec_ctx);
       grpc_iomgr_platform_flush();
       gpr_mu_lock(&g_mu);
       continue;
@@ -139,8 +137,8 @@ void grpc_iomgr_shutdown(void) {
   }
   gpr_mu_unlock(&g_mu);
 
-  grpc_timer_list_shutdown(&exec_ctx);
-  grpc_exec_ctx_finish(&exec_ctx);
+  grpc_timer_list_shutdown(exec_ctx);
+  grpc_exec_ctx_flush(exec_ctx);
 
   /* ensure all threads have left g_mu */
   gpr_mu_lock(&g_mu);
diff --git a/src/core/lib/iomgr/iomgr.h b/src/core/lib/iomgr/iomgr.h
index c1cfaf302e..245a1e08aa 100644
--- a/src/core/lib/iomgr/iomgr.h
+++ b/src/core/lib/iomgr/iomgr.h
@@ -34,12 +34,14 @@
 #ifndef GRPC_CORE_LIB_IOMGR_IOMGR_H
 #define GRPC_CORE_LIB_IOMGR_IOMGR_H
 
+#include <grpc/impl/codegen/exec_ctx_fwd.h>
 #include "src/core/lib/iomgr/port.h"
 
 /** Initializes the iomgr. */
 void grpc_iomgr_init(void);
 
-/** Signals the intention to shutdown the iomgr. */
-void grpc_iomgr_shutdown(void);
+/** Signals the intention to shutdown the iomgr. Expects to be able to flush
+ * exec_ctx. */
+void grpc_iomgr_shutdown(grpc_exec_ctx *exec_ctx);
 
 #endif /* GRPC_CORE_LIB_IOMGR_IOMGR_H */
diff --git a/src/core/lib/iomgr/resource_quota.c b/src/core/lib/iomgr/resource_quota.c
index 237da5293e..19a16b34ed 100644
--- a/src/core/lib/iomgr/resource_quota.c
+++ b/src/core/lib/iomgr/resource_quota.c
@@ -264,14 +264,14 @@ static void rq_step(grpc_exec_ctx *exec_ctx, void *rq, grpc_error *error) {
   }
 
 done:
-  grpc_resource_quota_internal_unref(exec_ctx, resource_quota);
+  grpc_resource_quota_unref_internal(exec_ctx, resource_quota);
 }
 
 static void rq_step_sched(grpc_exec_ctx *exec_ctx,
                           grpc_resource_quota *resource_quota) {
   if (resource_quota->step_scheduled) return;
   resource_quota->step_scheduled = true;
-  grpc_resource_quota_internal_ref(resource_quota);
+  grpc_resource_quota_ref_internal(resource_quota);
   grpc_closure_sched(exec_ctx, &resource_quota->rq_step_closure,
                      GRPC_ERROR_NONE);
 }
@@ -363,7 +363,7 @@ static bool rq_reclaim(grpc_exec_ctx *exec_ctx,
             destructive ? "destructive" : "benign");
   }
   resource_quota->reclaiming = true;
-  grpc_resource_quota_internal_ref(resource_quota);
+  grpc_resource_quota_ref_internal(resource_quota);
   grpc_closure *c = resource_user->reclaimers[destructive];
   GPR_ASSERT(c);
   resource_quota->debug_only_last_reclaimer_resource_user = resource_user;
@@ -389,21 +389,10 @@ static void ru_slice_ref(void *p) {
   gpr_ref(&rc->refs);
 }
 
-static void ru_slice_unref(void *p) {
+static void ru_slice_unref(grpc_exec_ctx *exec_ctx, void *p) {
   ru_slice_refcount *rc = p;
   if (gpr_unref(&rc->refs)) {
-    /* TODO(ctiller): this is dangerous, but I think safe for now:
-       we have no guarantee here that we're at a safe point for creating an
-       execution context, but we have no way of writing this code otherwise.
-       In the future: consider lifting grpc_slice to grpc, and offering an
-       internal_{ref,unref} pair that is execution context aware.
-       Alternatively,
-       make exec_ctx be thread local and 'do the right thing' (whatever that
-       is)
-       if NULL */
-    grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
-    grpc_resource_user_free(&exec_ctx, rc->resource_user, rc->size);
-    grpc_exec_ctx_finish(&exec_ctx);
+    grpc_resource_user_free(exec_ctx, rc->resource_user, rc->size);
     gpr_free(rc);
   }
 }
@@ -522,7 +511,7 @@ static void ru_destroy(grpc_exec_ctx *exec_ctx, void *ru, grpc_error *error) {
     resource_user->resource_quota->free_pool += resource_user->free_pool;
     rq_step_sched(exec_ctx, resource_user->resource_quota);
   }
-  grpc_resource_quota_internal_unref(exec_ctx, resource_user->resource_quota);
+  grpc_resource_quota_unref_internal(exec_ctx, resource_user->resource_quota);
   gpr_mu_destroy(&resource_user->mu);
   gpr_free(resource_user->name);
   gpr_free(resource_user);
@@ -559,7 +548,7 @@ static void rq_resize(grpc_exec_ctx *exec_ctx, void *args, grpc_error *error) {
   a->resource_quota->free_pool += delta;
   rq_update_estimate(a->resource_quota);
   rq_step_sched(exec_ctx, a->resource_quota);
-  grpc_resource_quota_internal_unref(exec_ctx, a->resource_quota);
+  grpc_resource_quota_unref_internal(exec_ctx, a->resource_quota);
   gpr_free(a);
 }
 
@@ -568,7 +557,7 @@ static void rq_reclamation_done(grpc_exec_ctx *exec_ctx, void *rq,
   grpc_resource_quota *resource_quota = rq;
   resource_quota->reclaiming = false;
   rq_step_sched(exec_ctx, resource_quota);
-  grpc_resource_quota_internal_unref(exec_ctx, resource_quota);
+  grpc_resource_quota_unref_internal(exec_ctx, resource_quota);
 }
 
 /*******************************************************************************
@@ -603,7 +592,7 @@ grpc_resource_quota *grpc_resource_quota_create(const char *name) {
   return resource_quota;
 }
 
-void grpc_resource_quota_internal_unref(grpc_exec_ctx *exec_ctx,
+void grpc_resource_quota_unref_internal(grpc_exec_ctx *exec_ctx,
                                         grpc_resource_quota *resource_quota) {
   if (gpr_unref(&resource_quota->refs)) {
     grpc_combiner_destroy(exec_ctx, resource_quota->combiner);
@@ -615,11 +604,11 @@ void grpc_resource_quota_internal_unref(grpc_exec_ctx *exec_ctx,
 /* Public API */
 void grpc_resource_quota_unref(grpc_resource_quota *resource_quota) {
   grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
-  grpc_resource_quota_internal_unref(&exec_ctx, resource_quota);
+  grpc_resource_quota_unref_internal(&exec_ctx, resource_quota);
   grpc_exec_ctx_finish(&exec_ctx);
 }
 
-grpc_resource_quota *grpc_resource_quota_internal_ref(
+grpc_resource_quota *grpc_resource_quota_ref_internal(
     grpc_resource_quota *resource_quota) {
   gpr_ref(&resource_quota->refs);
   return resource_quota;
@@ -627,7 +616,7 @@ grpc_resource_quota *grpc_resource_quota_internal_ref(
 
 /* Public API */
 void grpc_resource_quota_ref(grpc_resource_quota *resource_quota) {
-  grpc_resource_quota_internal_ref(resource_quota);
+  grpc_resource_quota_ref_internal(resource_quota);
 }
 
 double grpc_resource_quota_get_memory_pressure(
@@ -642,7 +631,7 @@ void grpc_resource_quota_resize(grpc_resource_quota *resource_quota,
                                 size_t size) {
   grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
   rq_resize_args *a = gpr_malloc(sizeof(*a));
-  a->resource_quota = grpc_resource_quota_internal_ref(resource_quota);
+  a->resource_quota = grpc_resource_quota_ref_internal(resource_quota);
   a->size = (int64_t)size;
   grpc_closure_init(&a->closure, rq_resize, a, grpc_schedule_on_exec_ctx);
   grpc_closure_sched(&exec_ctx, &a->closure, GRPC_ERROR_NONE);
@@ -658,7 +647,7 @@ grpc_resource_quota *grpc_resource_quota_from_channel_args(
   for (size_t i = 0; i < channel_args->num_args; i++) {
     if (0 == strcmp(channel_args->args[i].key, GRPC_ARG_RESOURCE_QUOTA)) {
       if (channel_args->args[i].type == GRPC_ARG_POINTER) {
-        return grpc_resource_quota_internal_ref(
+        return grpc_resource_quota_ref_internal(
             channel_args->args[i].value.pointer.p);
       } else {
         gpr_log(GPR_DEBUG, GRPC_ARG_RESOURCE_QUOTA " should be a pointer");
@@ -673,7 +662,9 @@ static void *rq_copy(void *rq) {
   return rq;
 }
 
-static void rq_destroy(void *rq) { grpc_resource_quota_unref(rq); }
+static void rq_destroy(grpc_exec_ctx *exec_ctx, void *rq) {
+  grpc_resource_quota_unref_internal(exec_ctx, rq);
+}
 
 static int rq_cmp(void *a, void *b) { return GPR_ICMP(a, b); }
 
@@ -690,7 +681,7 @@ grpc_resource_user *grpc_resource_user_create(
     grpc_resource_quota *resource_quota, const char *name) {
   grpc_resource_user *resource_user = gpr_malloc(sizeof(*resource_user));
   resource_user->resource_quota =
-      grpc_resource_quota_internal_ref(resource_quota);
+      grpc_resource_quota_ref_internal(resource_quota);
   grpc_closure_init(&resource_user->allocate_closure, &ru_allocate,
                     resource_user,
                     grpc_combiner_scheduler(resource_quota->combiner, false));
diff --git a/src/core/lib/iomgr/resource_quota.h b/src/core/lib/iomgr/resource_quota.h
index e3ff99e0aa..e7ba144188 100644
--- a/src/core/lib/iomgr/resource_quota.h
+++ b/src/core/lib/iomgr/resource_quota.h
@@ -77,9 +77,9 @@
 
 extern int grpc_resource_quota_trace;
 
-grpc_resource_quota *grpc_resource_quota_internal_ref(
+grpc_resource_quota *grpc_resource_quota_ref_internal(
     grpc_resource_quota *resource_quota);
-void grpc_resource_quota_internal_unref(grpc_exec_ctx *exec_ctx,
+void grpc_resource_quota_unref_internal(grpc_exec_ctx *exec_ctx,
                                         grpc_resource_quota *resource_quota);
 grpc_resource_quota *grpc_resource_quota_from_channel_args(
     const grpc_channel_args *channel_args);
diff --git a/src/core/lib/iomgr/socket_mutator.c b/src/core/lib/iomgr/socket_mutator.c
index 8b1efb6bab..34b61dcfe5 100644
--- a/src/core/lib/iomgr/socket_mutator.c
+++ b/src/core/lib/iomgr/socket_mutator.c
@@ -76,7 +76,7 @@ static void *socket_mutator_arg_copy(void *p) {
   return grpc_socket_mutator_ref(p);
 }
 
-static void socket_mutator_arg_destroy(void *p) {
+static void socket_mutator_arg_destroy(grpc_exec_ctx *exec_ctx, void *p) {
   grpc_socket_mutator_unref(p);
 }
 
diff --git a/src/core/lib/iomgr/tcp_client_posix.c b/src/core/lib/iomgr/tcp_client_posix.c
index d089d2bc3b..9a77c92016 100644
--- a/src/core/lib/iomgr/tcp_client_posix.c
+++ b/src/core/lib/iomgr/tcp_client_posix.c
@@ -65,6 +65,7 @@ typedef struct {
   grpc_fd *fd;
   gpr_timespec deadline;
   grpc_timer alarm;
+  grpc_closure on_alarm;
   int refs;
   grpc_closure write_closure;
   grpc_pollset_set *interested_parties;
@@ -128,7 +129,7 @@ static void tc_on_alarm(grpc_exec_ctx *exec_ctx, void *acp, grpc_error *error) {
   if (done) {
     gpr_mu_destroy(&ac->mu);
     gpr_free(ac->addr_str);
-    grpc_channel_args_destroy(ac->channel_args);
+    grpc_channel_args_destroy(exec_ctx, ac->channel_args);
     gpr_free(ac);
   }
 }
@@ -148,8 +149,8 @@ grpc_endpoint *grpc_tcp_client_create_from_fd(
             &channel_args->args[i], options);
       } else if (0 ==
                  strcmp(channel_args->args[i].key, GRPC_ARG_RESOURCE_QUOTA)) {
-        grpc_resource_quota_internal_unref(exec_ctx, resource_quota);
-        resource_quota = grpc_resource_quota_internal_ref(
+        grpc_resource_quota_unref_internal(exec_ctx, resource_quota);
+        resource_quota = grpc_resource_quota_ref_internal(
             channel_args->args[i].value.pointer.p);
       }
     }
@@ -157,7 +158,7 @@ grpc_endpoint *grpc_tcp_client_create_from_fd(
 
   grpc_endpoint *ep =
       grpc_tcp_create(fd, resource_quota, tcp_read_chunk_size, addr_str);
-  grpc_resource_quota_internal_unref(exec_ctx, resource_quota);
+  grpc_resource_quota_unref_internal(exec_ctx, resource_quota);
   return ep;
 }
 
@@ -262,7 +263,7 @@ finish:
   if (done) {
     gpr_mu_destroy(&ac->mu);
     gpr_free(ac->addr_str);
-    grpc_channel_args_destroy(ac->channel_args);
+    grpc_channel_args_destroy(exec_ctx, ac->channel_args);
     gpr_free(ac);
   }
   grpc_closure_sched(exec_ctx, closure, error);
@@ -352,9 +353,10 @@ static void tcp_client_connect_impl(grpc_exec_ctx *exec_ctx,
   }
 
   gpr_mu_lock(&ac->mu);
+  grpc_closure_init(&ac->on_alarm, tc_on_alarm, ac, grpc_schedule_on_exec_ctx);
   grpc_timer_init(exec_ctx, &ac->alarm,
                   gpr_convert_clock_type(deadline, GPR_CLOCK_MONOTONIC),
-                  tc_on_alarm, ac, gpr_now(GPR_CLOCK_MONOTONIC));
+                  &ac->on_alarm, gpr_now(GPR_CLOCK_MONOTONIC));
   grpc_fd_notify_on_write(exec_ctx, ac->fd, &ac->write_closure);
   gpr_mu_unlock(&ac->mu);
 
diff --git a/src/core/lib/iomgr/tcp_client_uv.c b/src/core/lib/iomgr/tcp_client_uv.c
index b1664b85fd..5225a5402b 100644
--- a/src/core/lib/iomgr/tcp_client_uv.c
+++ b/src/core/lib/iomgr/tcp_client_uv.c
@@ -49,6 +49,7 @@
 typedef struct grpc_uv_tcp_connect {
   uv_connect_t connect_req;
   grpc_timer alarm;
+  grpc_closure on_alarm;
   uv_tcp_t *tcp_handle;
   grpc_closure *closure;
   grpc_endpoint **endpoint;
@@ -59,7 +60,7 @@ typedef struct grpc_uv_tcp_connect {
 
 static void uv_tcp_connect_cleanup(grpc_exec_ctx *exec_ctx,
                                    grpc_uv_tcp_connect *connect) {
-  grpc_resource_quota_internal_unref(exec_ctx, connect->resource_quota);
+  grpc_resource_quota_unref_internal(exec_ctx, connect->resource_quota);
   gpr_free(connect);
 }
 
@@ -128,8 +129,8 @@ static void tcp_client_connect_impl(grpc_exec_ctx *exec_ctx,
   if (channel_args != NULL) {
     for (size_t i = 0; i < channel_args->num_args; i++) {
       if (0 == strcmp(channel_args->args[i].key, GRPC_ARG_RESOURCE_QUOTA)) {
-        grpc_resource_quota_internal_unref(exec_ctx, resource_quota);
-        resource_quota = grpc_resource_quota_internal_ref(
+        grpc_resource_quota_unref_internal(exec_ctx, resource_quota);
+        resource_quota = grpc_resource_quota_ref_internal(
             channel_args->args[i].value.pointer.p);
       }
     }
@@ -148,9 +149,11 @@ static void tcp_client_connect_impl(grpc_exec_ctx *exec_ctx,
   uv_tcp_connect(&connect->connect_req, connect->tcp_handle,
                  (const struct sockaddr *)resolved_addr->addr,
                  uv_tc_on_connect);
+  grpc_closure_init(&connect->on_alarm, uv_tc_on_alarm, connect,
+                    grpc_schedule_on_exec_ctx);
   grpc_timer_init(exec_ctx, &connect->alarm,
                   gpr_convert_clock_type(deadline, GPR_CLOCK_MONOTONIC),
-                  uv_tc_on_alarm, connect, gpr_now(GPR_CLOCK_MONOTONIC));
+                  &connect->on_alarm, gpr_now(GPR_CLOCK_MONOTONIC));
 }
 
 // overridden by api_fuzzer.c
diff --git a/src/core/lib/iomgr/tcp_client_windows.c b/src/core/lib/iomgr/tcp_client_windows.c
index 692252bbe0..1e84ec3a1e 100644
--- a/src/core/lib/iomgr/tcp_client_windows.c
+++ b/src/core/lib/iomgr/tcp_client_windows.c
@@ -58,6 +58,7 @@ typedef struct {
   grpc_winsocket *socket;
   gpr_timespec deadline;
   grpc_timer alarm;
+  grpc_closure on_alarm;
   char *addr_name;
   int refs;
   grpc_closure on_connect;
@@ -71,7 +72,7 @@ static void async_connect_unlock_and_cleanup(grpc_exec_ctx *exec_ctx,
   int done = (--ac->refs == 0);
   gpr_mu_unlock(&ac->mu);
   if (done) {
-    grpc_resource_quota_internal_unref(exec_ctx, ac->resource_quota);
+    grpc_resource_quota_unref_internal(exec_ctx, ac->resource_quota);
     gpr_mu_destroy(&ac->mu);
     gpr_free(ac->addr_name);
     gpr_free(ac);
@@ -157,8 +158,8 @@ void grpc_tcp_client_connect(grpc_exec_ctx *exec_ctx, grpc_closure *on_done,
   if (channel_args != NULL) {
     for (size_t i = 0; i < channel_args->num_args; i++) {
       if (0 == strcmp(channel_args->args[i].key, GRPC_ARG_RESOURCE_QUOTA)) {
-        grpc_resource_quota_internal_unref(exec_ctx, resource_quota);
-        resource_quota = grpc_resource_quota_internal_ref(
+        grpc_resource_quota_unref_internal(exec_ctx, resource_quota);
+        resource_quota = grpc_resource_quota_ref_internal(
             channel_args->args[i].value.pointer.p);
       }
     }
@@ -229,7 +230,8 @@ void grpc_tcp_client_connect(grpc_exec_ctx *exec_ctx, grpc_closure *on_done,
   ac->resource_quota = resource_quota;
   grpc_closure_init(&ac->on_connect, on_connect, ac, grpc_schedule_on_exec_ctx);
 
-  grpc_timer_init(exec_ctx, &ac->alarm, deadline, on_alarm, ac,
+  grpc_closure_init(&ac->on_alarm, on_alarm, ac, grpc_schedule_on_exec_ctx);
+  grpc_timer_init(exec_ctx, &ac->alarm, deadline, &ac->on_alarm,
                   gpr_now(GPR_CLOCK_MONOTONIC));
   grpc_socket_notify_on_write(exec_ctx, socket, &ac->on_connect);
   return;
@@ -246,7 +248,7 @@ failure:
   } else if (sock != INVALID_SOCKET) {
     closesocket(sock);
   }
-  grpc_resource_quota_internal_unref(exec_ctx, resource_quota);
+  grpc_resource_quota_unref_internal(exec_ctx, resource_quota);
   grpc_closure_sched(exec_ctx, on_done, final_error);
 }
 
diff --git a/src/core/lib/iomgr/tcp_posix.c b/src/core/lib/iomgr/tcp_posix.c
index 21a0371d10..ece44978b0 100644
--- a/src/core/lib/iomgr/tcp_posix.c
+++ b/src/core/lib/iomgr/tcp_posix.c
@@ -56,6 +56,7 @@
 #include "src/core/lib/debug/trace.h"
 #include "src/core/lib/iomgr/ev_posix.h"
 #include "src/core/lib/profiling/timers.h"
+#include "src/core/lib/slice/slice_internal.h"
 #include "src/core/lib/slice/slice_string_helpers.h"
 #include "src/core/lib/support/string.h"
 
@@ -127,7 +128,7 @@ static void tcp_shutdown(grpc_exec_ctx *exec_ctx, grpc_endpoint *ep) {
 static void tcp_free(grpc_exec_ctx *exec_ctx, grpc_tcp *tcp) {
   grpc_fd_orphan(exec_ctx, tcp->em_fd, tcp->release_fd_cb, tcp->release_fd,
                  "tcp_unref_orphan");
-  grpc_slice_buffer_destroy(&tcp->last_read_buffer);
+  grpc_slice_buffer_destroy_internal(exec_ctx, &tcp->last_read_buffer);
   grpc_resource_user_unref(exec_ctx, tcp->resource_user);
   gpr_free(tcp->peer_string);
   gpr_free(tcp);
@@ -168,7 +169,7 @@ static void tcp_ref(grpc_tcp *tcp) { gpr_ref(&tcp->refcount); }
 static void tcp_destroy(grpc_exec_ctx *exec_ctx, grpc_endpoint *ep) {
   grpc_network_status_unregister_endpoint(ep);
   grpc_tcp *tcp = (grpc_tcp *)ep;
-  grpc_slice_buffer_reset_and_unref(&tcp->last_read_buffer);
+  grpc_slice_buffer_reset_and_unref_internal(exec_ctx, &tcp->last_read_buffer);
   TCP_UNREF(exec_ctx, tcp, "destroy");
 }
 
@@ -235,14 +236,15 @@ static void tcp_do_read(grpc_exec_ctx *exec_ctx, grpc_tcp *tcp) {
       /* We've consumed the edge, request a new one */
       grpc_fd_notify_on_read(exec_ctx, tcp->em_fd, &tcp->read_closure);
     } else {
-      grpc_slice_buffer_reset_and_unref(tcp->incoming_buffer);
+      grpc_slice_buffer_reset_and_unref_internal(exec_ctx,
+                                                 tcp->incoming_buffer);
       call_read_cb(exec_ctx, tcp,
                    tcp_annotate_error(GRPC_OS_ERROR(errno, "recvmsg"), tcp));
       TCP_UNREF(exec_ctx, tcp, "read");
     }
   } else if (read_bytes == 0) {
     /* 0 read size ==> end of stream */
-    grpc_slice_buffer_reset_and_unref(tcp->incoming_buffer);
+    grpc_slice_buffer_reset_and_unref_internal(exec_ctx, tcp->incoming_buffer);
     call_read_cb(exec_ctx, tcp,
                  tcp_annotate_error(GRPC_ERROR_CREATE("Socket closed"), tcp));
     TCP_UNREF(exec_ctx, tcp, "read");
@@ -268,8 +270,9 @@ static void tcp_read_allocation_done(grpc_exec_ctx *exec_ctx, void *tcpp,
                                      grpc_error *error) {
   grpc_tcp *tcp = tcpp;
   if (error != GRPC_ERROR_NONE) {
-    grpc_slice_buffer_reset_and_unref(tcp->incoming_buffer);
-    grpc_slice_buffer_reset_and_unref(&tcp->last_read_buffer);
+    grpc_slice_buffer_reset_and_unref_internal(exec_ctx, tcp->incoming_buffer);
+    grpc_slice_buffer_reset_and_unref_internal(exec_ctx,
+                                               &tcp->last_read_buffer);
     call_read_cb(exec_ctx, tcp, GRPC_ERROR_REF(error));
     TCP_UNREF(exec_ctx, tcp, "read");
   } else {
@@ -294,8 +297,9 @@ static void tcp_handle_read(grpc_exec_ctx *exec_ctx, void *arg /* grpc_tcp */,
   GPR_ASSERT(!tcp->finished_edge);
 
   if (error != GRPC_ERROR_NONE) {
-    grpc_slice_buffer_reset_and_unref(tcp->incoming_buffer);
-    grpc_slice_buffer_reset_and_unref(&tcp->last_read_buffer);
+    grpc_slice_buffer_reset_and_unref_internal(exec_ctx, tcp->incoming_buffer);
+    grpc_slice_buffer_reset_and_unref_internal(exec_ctx,
+                                               &tcp->last_read_buffer);
     call_read_cb(exec_ctx, tcp, GRPC_ERROR_REF(error));
     TCP_UNREF(exec_ctx, tcp, "read");
   } else {
@@ -309,7 +313,7 @@ static void tcp_read(grpc_exec_ctx *exec_ctx, grpc_endpoint *ep,
   GPR_ASSERT(tcp->read_cb == NULL);
   tcp->read_cb = cb;
   tcp->incoming_buffer = incoming_buffer;
-  grpc_slice_buffer_reset_and_unref(incoming_buffer);
+  grpc_slice_buffer_reset_and_unref_internal(exec_ctx, incoming_buffer);
   grpc_slice_buffer_swap(incoming_buffer, &tcp->last_read_buffer);
   TCP_REF(tcp, "read");
   if (tcp->finished_edge) {
@@ -578,7 +582,7 @@ void grpc_tcp_destroy_and_release_fd(grpc_exec_ctx *exec_ctx, grpc_endpoint *ep,
   GPR_ASSERT(ep->vtable == &vtable);
   tcp->release_fd = fd;
   tcp->release_fd_cb = done;
-  grpc_slice_buffer_reset_and_unref(&tcp->last_read_buffer);
+  grpc_slice_buffer_reset_and_unref_internal(exec_ctx, &tcp->last_read_buffer);
   TCP_UNREF(exec_ctx, tcp, "destroy");
 }
 
diff --git a/src/core/lib/iomgr/tcp_server_posix.c b/src/core/lib/iomgr/tcp_server_posix.c
index 6db624dd56..20efb678b2 100644
--- a/src/core/lib/iomgr/tcp_server_posix.c
+++ b/src/core/lib/iomgr/tcp_server_posix.c
@@ -167,18 +167,18 @@ grpc_error *grpc_tcp_server_create(grpc_exec_ctx *exec_ctx,
         s->so_reuseport =
             has_so_reuseport && (args->args[i].value.integer != 0);
       } else {
-        grpc_resource_quota_internal_unref(exec_ctx, s->resource_quota);
+        grpc_resource_quota_unref_internal(exec_ctx, s->resource_quota);
         gpr_free(s);
         return GRPC_ERROR_CREATE(GRPC_ARG_ALLOW_REUSEPORT
                                  " must be an integer");
       }
     } else if (0 == strcmp(GRPC_ARG_RESOURCE_QUOTA, args->args[i].key)) {
       if (args->args[i].type == GRPC_ARG_POINTER) {
-        grpc_resource_quota_internal_unref(exec_ctx, s->resource_quota);
+        grpc_resource_quota_unref_internal(exec_ctx, s->resource_quota);
         s->resource_quota =
-            grpc_resource_quota_internal_ref(args->args[i].value.pointer.p);
+            grpc_resource_quota_ref_internal(args->args[i].value.pointer.p);
       } else {
-        grpc_resource_quota_internal_unref(exec_ctx, s->resource_quota);
+        grpc_resource_quota_unref_internal(exec_ctx, s->resource_quota);
         gpr_free(s);
         return GRPC_ERROR_CREATE(GRPC_ARG_RESOURCE_QUOTA
                                  " must be a pointer to a buffer pool");
@@ -219,7 +219,7 @@ static void finish_shutdown(grpc_exec_ctx *exec_ctx, grpc_tcp_server *s) {
     gpr_free(sp);
   }
 
-  grpc_resource_quota_internal_unref(exec_ctx, s->resource_quota);
+  grpc_resource_quota_unref_internal(exec_ctx, s->resource_quota);
 
   gpr_free(s);
 }
diff --git a/src/core/lib/iomgr/tcp_server_uv.c b/src/core/lib/iomgr/tcp_server_uv.c
index 8abc60d624..eed2773f8a 100644
--- a/src/core/lib/iomgr/tcp_server_uv.c
+++ b/src/core/lib/iomgr/tcp_server_uv.c
@@ -89,11 +89,11 @@ grpc_error *grpc_tcp_server_create(grpc_exec_ctx *exec_ctx,
   for (size_t i = 0; i < (args == NULL ? 0 : args->num_args); i++) {
     if (0 == strcmp(GRPC_ARG_RESOURCE_QUOTA, args->args[i].key)) {
       if (args->args[i].type == GRPC_ARG_POINTER) {
-        grpc_resource_quota_internal_unref(exec_ctx, s->resource_quota);
+        grpc_resource_quota_unref_internal(exec_ctx, s->resource_quota);
         s->resource_quota =
-            grpc_resource_quota_internal_ref(args->args[i].value.pointer.p);
+            grpc_resource_quota_ref_internal(args->args[i].value.pointer.p);
       } else {
-        grpc_resource_quota_internal_unref(exec_ctx, s->resource_quota);
+        grpc_resource_quota_unref_internal(exec_ctx, s->resource_quota);
         gpr_free(s);
         return GRPC_ERROR_CREATE(GRPC_ARG_RESOURCE_QUOTA
                                  " must be a pointer to a buffer pool");
@@ -136,7 +136,7 @@ static void finish_shutdown(grpc_exec_ctx *exec_ctx, grpc_tcp_server *s) {
     gpr_free(sp->handle);
     gpr_free(sp);
   }
-  grpc_resource_quota_internal_unref(exec_ctx, s->resource_quota);
+  grpc_resource_quota_unref_internal(exec_ctx, s->resource_quota);
   gpr_free(s);
 }
 
diff --git a/src/core/lib/iomgr/tcp_server_windows.c b/src/core/lib/iomgr/tcp_server_windows.c
index 6302bff5d2..dafe851ce8 100644
--- a/src/core/lib/iomgr/tcp_server_windows.c
+++ b/src/core/lib/iomgr/tcp_server_windows.c
@@ -116,11 +116,11 @@ grpc_error *grpc_tcp_server_create(grpc_exec_ctx *exec_ctx,
   for (size_t i = 0; i < (args == NULL ? 0 : args->num_args); i++) {
     if (0 == strcmp(GRPC_ARG_RESOURCE_QUOTA, args->args[i].key)) {
       if (args->args[i].type == GRPC_ARG_POINTER) {
-        grpc_resource_quota_internal_unref(exec_ctx, s->resource_quota);
+        grpc_resource_quota_unref_internal(exec_ctx, s->resource_quota);
         s->resource_quota =
-            grpc_resource_quota_internal_ref(args->args[i].value.pointer.p);
+            grpc_resource_quota_ref_internal(args->args[i].value.pointer.p);
       } else {
-        grpc_resource_quota_internal_unref(exec_ctx, s->resource_quota);
+        grpc_resource_quota_unref_internal(exec_ctx, s->resource_quota);
         gpr_free(s);
         return GRPC_ERROR_CREATE(GRPC_ARG_RESOURCE_QUOTA
                                  " must be a pointer to a buffer pool");
@@ -155,7 +155,7 @@ static void destroy_server(grpc_exec_ctx *exec_ctx, void *arg,
     grpc_winsocket_destroy(sp->socket);
     gpr_free(sp);
   }
-  grpc_resource_quota_internal_unref(exec_ctx, s->resource_quota);
+  grpc_resource_quota_unref_internal(exec_ctx, s->resource_quota);
   gpr_free(s);
 }
 
@@ -184,7 +184,6 @@ void grpc_tcp_server_shutdown_starting_add(grpc_tcp_server *s,
 }
 
 static void tcp_server_destroy(grpc_exec_ctx *exec_ctx, grpc_tcp_server *s) {
-  int immediately_done = 0;
   grpc_tcp_listener *sp;
   gpr_mu_lock(&s->mu);
 
@@ -240,7 +239,7 @@ static grpc_error *prepare_socket(SOCKET sock,
     error = GRPC_WSA_ERROR(WSAGetLastError(), "getsockname");
     goto failure;
   }
-  sockname_temp.len = sockname_temp_len;
+  sockname_temp.len = (size_t)sockname_temp_len;
 
   *port = grpc_sockaddr_get_port(&sockname_temp);
   return GRPC_ERROR_NONE;
@@ -248,7 +247,7 @@ static grpc_error *prepare_socket(SOCKET sock,
 failure:
   GPR_ASSERT(error != GRPC_ERROR_NONE);
   char *tgtaddr = grpc_sockaddr_to_uri(addr);
-  grpc_error *final_error = grpc_error_set_int(
+  grpc_error_set_int(
       grpc_error_set_str(GRPC_ERROR_CREATE_REFERENCING(
                              "Failed to prepare server socket", &error, 1),
                          GRPC_ERROR_STR_TARGET_ADDRESS, tgtaddr),
@@ -261,7 +260,6 @@ failure:
 
 static void decrement_active_ports_and_notify_locked(grpc_exec_ctx *exec_ctx,
                                                      grpc_tcp_listener *sp) {
-  int notify = 0;
   sp->shutting_down = 0;
   GPR_ASSERT(sp->server->active_ports > 0);
   if (0 == --sp->server->active_ports) {
@@ -375,7 +373,7 @@ static void on_accept(grpc_exec_ctx *exec_ctx, void *arg, grpc_error *error) {
       int peer_name_len = (int)peer_name.len;
       err =
           getpeername(sock, (struct sockaddr *)peer_name.addr, &peer_name_len);
-      peer_name.len = peer_name_len;
+      peer_name.len = (size_t)peer_name_len;
       if (!err) {
         peer_name_string = grpc_sockaddr_to_uri(&peer_name);
       } else {
@@ -498,7 +496,7 @@ grpc_error *grpc_tcp_server_add_port(grpc_tcp_server *s,
       if (0 == getsockname(sp->socket->socket,
                            (struct sockaddr *)sockname_temp.addr,
                            &sockname_temp_len)) {
-        sockname_temp.len = sockname_temp_len;
+        sockname_temp.len = (size_t)sockname_temp_len;
         *port = grpc_sockaddr_get_port(&sockname_temp);
         if (*port > 0) {
           allocated_addr = gpr_malloc(sizeof(grpc_resolved_address));
diff --git a/src/core/lib/iomgr/tcp_uv.c b/src/core/lib/iomgr/tcp_uv.c
index 4be95457d5..3ddc79706b 100644
--- a/src/core/lib/iomgr/tcp_uv.c
+++ b/src/core/lib/iomgr/tcp_uv.c
@@ -181,7 +181,7 @@ static void uv_endpoint_read(grpc_exec_ctx *exec_ctx, grpc_endpoint *ep,
   GPR_ASSERT(tcp->read_cb == NULL);
   tcp->read_cb = cb;
   tcp->read_slices = read_slices;
-  grpc_slice_buffer_reset_and_unref(read_slices);
+  grpc_slice_buffer_reset_and_unref_internal(exec_ctx, read_slices);
   TCP_REF(tcp, "read");
   // TODO(murgatroid99): figure out what the return value here means
   status =
diff --git a/src/core/lib/iomgr/tcp_windows.c b/src/core/lib/iomgr/tcp_windows.c
index fa13ac1d25..84f791ba07 100644
--- a/src/core/lib/iomgr/tcp_windows.c
+++ b/src/core/lib/iomgr/tcp_windows.c
@@ -53,6 +53,7 @@
 #include "src/core/lib/iomgr/socket_windows.h"
 #include "src/core/lib/iomgr/tcp_client.h"
 #include "src/core/lib/iomgr/timer.h"
+#include "src/core/lib/slice/slice_internal.h"
 
 #if defined(__MSYS__) && defined(GPR_ARCH_64)
 /* Nasty workaround for nasty bug when using the 64 bits msys compiler
@@ -174,13 +175,13 @@ static void on_read(grpc_exec_ctx *exec_ctx, void *tcpp, grpc_error *error) {
       char *utf8_message = gpr_format_message(info->wsa_error);
       error = GRPC_ERROR_CREATE(utf8_message);
       gpr_free(utf8_message);
-      grpc_slice_unref(tcp->read_slice);
+      grpc_slice_unref_internal(exec_ctx, tcp->read_slice);
     } else {
       if (info->bytes_transfered != 0 && !tcp->shutting_down) {
         sub = grpc_slice_sub_no_ref(tcp->read_slice, 0, info->bytes_transfered);
         grpc_slice_buffer_add(tcp->read_slices, sub);
       } else {
-        grpc_slice_unref(tcp->read_slice);
+        grpc_slice_unref_internal(exec_ctx, tcp->read_slice);
         error = GRPC_ERROR_CREATE("End of TCP stream");
       }
     }
@@ -209,7 +210,7 @@ static void win_read(grpc_exec_ctx *exec_ctx, grpc_endpoint *ep,
 
   tcp->read_cb = cb;
   tcp->read_slices = read_slices;
-  grpc_slice_buffer_reset_and_unref(read_slices);
+  grpc_slice_buffer_reset_and_unref_internal(exec_ctx, read_slices);
 
   tcp->read_slice = grpc_slice_malloc(8192);
 
diff --git a/src/core/lib/iomgr/timer.h b/src/core/lib/iomgr/timer.h
index 20fe98c4a7..d84a278b18 100644
--- a/src/core/lib/iomgr/timer.h
+++ b/src/core/lib/iomgr/timer.h
@@ -49,15 +49,15 @@
 
 typedef struct grpc_timer grpc_timer;
 
-/* Initialize *timer. When expired or canceled, timer_cb will be called with
-   *timer_cb_arg and error set to indicate if it expired (GRPC_ERROR_NONE) or
-   was canceled (GRPC_ERROR_CANCELLED). timer_cb is guaranteed to be called
-   exactly once, and application code should check the error to determine
-   how it was invoked. The application callback is also responsible for
-   maintaining information about when to free up any user-level state. */
+/* Initialize *timer. When expired or canceled, closure will be called with
+   error set to indicate if it expired (GRPC_ERROR_NONE) or was canceled
+   (GRPC_ERROR_CANCELLED). timer_cb is guaranteed to be called exactly once, and
+   application code should check the error to determine how it was invoked. The
+   application callback is also responsible for maintaining information about
+   when to free up any user-level state. */
 void grpc_timer_init(grpc_exec_ctx *exec_ctx, grpc_timer *timer,
-                     gpr_timespec deadline, grpc_iomgr_cb_func timer_cb,
-                     void *timer_cb_arg, gpr_timespec now);
+                     gpr_timespec deadline, grpc_closure *closure,
+                     gpr_timespec now);
 
 /* Note that there is no timer destroy function. This is because the
    timer is a one-time occurrence with a guarantee that the callback will
diff --git a/src/core/lib/iomgr/timer_generic.c b/src/core/lib/iomgr/timer_generic.c
index ecd3b284dc..40c8351472 100644
--- a/src/core/lib/iomgr/timer_generic.c
+++ b/src/core/lib/iomgr/timer_generic.c
@@ -178,28 +178,27 @@ static void note_deadline_change(shard_type *shard) {
 }
 
 void grpc_timer_init(grpc_exec_ctx *exec_ctx, grpc_timer *timer,
-                     gpr_timespec deadline, grpc_iomgr_cb_func timer_cb,
-                     void *timer_cb_arg, gpr_timespec now) {
+                     gpr_timespec deadline, grpc_closure *closure,
+                     gpr_timespec now) {
   int is_first_timer = 0;
   shard_type *shard = &g_shards[shard_idx(timer)];
   GPR_ASSERT(deadline.clock_type == g_clock_type);
   GPR_ASSERT(now.clock_type == g_clock_type);
-  grpc_closure_init(&timer->closure, timer_cb, timer_cb_arg,
-                    grpc_schedule_on_exec_ctx);
+  timer->closure = closure;
   timer->deadline = deadline;
   timer->triggered = 0;
 
   if (!g_initialized) {
     timer->triggered = 1;
     grpc_closure_sched(
-        exec_ctx, &timer->closure,
+        exec_ctx, timer->closure,
         GRPC_ERROR_CREATE("Attempt to create timer before initialization"));
     return;
   }
 
   if (gpr_time_cmp(deadline, now) <= 0) {
     timer->triggered = 1;
-    grpc_closure_sched(exec_ctx, &timer->closure, GRPC_ERROR_NONE);
+    grpc_closure_sched(exec_ctx, timer->closure, GRPC_ERROR_NONE);
     return;
   }
 
@@ -251,7 +250,7 @@ void grpc_timer_cancel(grpc_exec_ctx *exec_ctx, grpc_timer *timer) {
   shard_type *shard = &g_shards[shard_idx(timer)];
   gpr_mu_lock(&shard->mu);
   if (!timer->triggered) {
-    grpc_closure_sched(exec_ctx, &timer->closure, GRPC_ERROR_CANCELLED);
+    grpc_closure_sched(exec_ctx, timer->closure, GRPC_ERROR_CANCELLED);
     timer->triggered = 1;
     if (timer->heap_index == INVALID_HEAP_INDEX) {
       list_remove(timer);
@@ -317,7 +316,7 @@ static size_t pop_timers(grpc_exec_ctx *exec_ctx, shard_type *shard,
   grpc_timer *timer;
   gpr_mu_lock(&shard->mu);
   while ((timer = pop_one(shard, now))) {
-    grpc_closure_sched(exec_ctx, &timer->closure, GRPC_ERROR_REF(error));
+    grpc_closure_sched(exec_ctx, timer->closure, GRPC_ERROR_REF(error));
     n++;
   }
   *new_min_deadline = compute_min_deadline(shard);
diff --git a/src/core/lib/iomgr/timer_generic.h b/src/core/lib/iomgr/timer_generic.h
index e4494adb5f..9d901c7e68 100644
--- a/src/core/lib/iomgr/timer_generic.h
+++ b/src/core/lib/iomgr/timer_generic.h
@@ -43,7 +43,7 @@ struct grpc_timer {
   int triggered;
   struct grpc_timer *next;
   struct grpc_timer *prev;
-  grpc_closure closure;
+  grpc_closure *closure;
 };
 
 #endif /* GRPC_CORE_LIB_IOMGR_TIMER_GENERIC_H */
diff --git a/src/core/lib/iomgr/timer_uv.c b/src/core/lib/iomgr/timer_uv.c
index 00b835ffb8..fa2cdee964 100644
--- a/src/core/lib/iomgr/timer_uv.c
+++ b/src/core/lib/iomgr/timer_uv.c
@@ -55,21 +55,20 @@ void run_expired_timer(uv_timer_t *handle) {
   grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
   GPR_ASSERT(!timer->triggered);
   timer->triggered = 1;
-  grpc_closure_sched(&exec_ctx, &timer->closure, GRPC_ERROR_NONE);
+  grpc_closure_sched(&exec_ctx, timer->closure, GRPC_ERROR_NONE);
   stop_uv_timer(handle);
   grpc_exec_ctx_finish(&exec_ctx);
 }
 
 void grpc_timer_init(grpc_exec_ctx *exec_ctx, grpc_timer *timer,
-                     gpr_timespec deadline, grpc_iomgr_cb_func timer_cb,
-                     void *timer_cb_arg, gpr_timespec now) {
+                     gpr_timespec deadline, grpc_closure *closure,
+                     gpr_timespec now) {
   uint64_t timeout;
   uv_timer_t *uv_timer;
-  grpc_closure_init(&timer->closure, timer_cb, timer_cb_arg,
-                    grpc_schedule_on_exec_ctx);
+  timer->closure = closure;
   if (gpr_time_cmp(deadline, now) <= 0) {
     timer->triggered = 1;
-    grpc_closure_sched(exec_ctx, &timer->closure, GRPC_ERROR_NONE);
+    grpc_closure_sched(exec_ctx, timer->closure, GRPC_ERROR_NONE);
     return;
   }
   timer->triggered = 0;
@@ -84,7 +83,7 @@ void grpc_timer_init(grpc_exec_ctx *exec_ctx, grpc_timer *timer,
 void grpc_timer_cancel(grpc_exec_ctx *exec_ctx, grpc_timer *timer) {
   if (!timer->triggered) {
     timer->triggered = 1;
-    grpc_closure_sched(exec_ctx, &timer->closure, GRPC_ERROR_CANCELLED);
+    grpc_closure_sched(exec_ctx, timer->closure, GRPC_ERROR_CANCELLED);
     stop_uv_timer((uv_timer_t *)timer->uv_timer);
   }
 }
diff --git a/src/core/lib/iomgr/timer_uv.h b/src/core/lib/iomgr/timer_uv.h
index 3de383ebd5..13cf8bd4fa 100644
--- a/src/core/lib/iomgr/timer_uv.h
+++ b/src/core/lib/iomgr/timer_uv.h
@@ -37,7 +37,7 @@
 #include "src/core/lib/iomgr/exec_ctx.h"
 
 struct grpc_timer {
-  grpc_closure closure;
+  grpc_closure *closure;
   /* This is actually a uv_timer_t*, but we want to keep platform-specific
      types out of headers */
   void *uv_timer;
diff --git a/src/core/lib/security/context/security_context.c b/src/core/lib/security/context/security_context.c
index 2204fadf54..fe82fabc31 100644
--- a/src/core/lib/security/context/security_context.c
+++ b/src/core/lib/security/context/security_context.c
@@ -47,6 +47,7 @@
 
 grpc_call_error grpc_call_set_credentials(grpc_call *call,
                                           grpc_call_credentials *creds) {
+  grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
   grpc_client_security_context *ctx = NULL;
   GRPC_API_TRACE("grpc_call_set_credentials(call=%p, creds=%p)", 2,
                  (call, creds));
@@ -62,9 +63,10 @@ grpc_call_error grpc_call_set_credentials(grpc_call *call,
     grpc_call_context_set(call, GRPC_CONTEXT_SECURITY, ctx,
                           grpc_client_security_context_destroy);
   } else {
-    grpc_call_credentials_unref(ctx->creds);
+    grpc_call_credentials_unref(&exec_ctx, ctx->creds);
     ctx->creds = grpc_call_credentials_ref(creds);
   }
+  grpc_exec_ctx_finish(&exec_ctx);
   return GRPC_CALL_OK;
 }
 
@@ -96,13 +98,15 @@ grpc_client_security_context *grpc_client_security_context_create(void) {
 }
 
 void grpc_client_security_context_destroy(void *ctx) {
+  grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
   grpc_client_security_context *c = (grpc_client_security_context *)ctx;
-  grpc_call_credentials_unref(c->creds);
+  grpc_call_credentials_unref(&exec_ctx, c->creds);
   GRPC_AUTH_CONTEXT_UNREF(c->auth_context, "client_security_context");
   if (c->extension.instance != NULL && c->extension.destroy != NULL) {
     c->extension.destroy(c->extension.instance);
   }
   gpr_free(ctx);
+  grpc_exec_ctx_finish(&exec_ctx);
 }
 
 /* --- grpc_server_security_context --- */
@@ -307,7 +311,7 @@ void grpc_auth_property_reset(grpc_auth_property *property) {
   memset(property, 0, sizeof(grpc_auth_property));
 }
 
-static void auth_context_pointer_arg_destroy(void *p) {
+static void auth_context_pointer_arg_destroy(grpc_exec_ctx *exec_ctx, void *p) {
   GRPC_AUTH_CONTEXT_UNREF(p, "auth_context_pointer_arg");
 }
 
diff --git a/src/core/lib/security/credentials/composite/composite_credentials.c b/src/core/lib/security/credentials/composite/composite_credentials.c
index d55d00b7b6..be1588dd8b 100644
--- a/src/core/lib/security/credentials/composite/composite_credentials.c
+++ b/src/core/lib/security/credentials/composite/composite_credentials.c
@@ -54,18 +54,20 @@ typedef struct {
   grpc_credentials_metadata_cb cb;
 } grpc_composite_call_credentials_metadata_context;
 
-static void composite_call_destruct(grpc_call_credentials *creds) {
+static void composite_call_destruct(grpc_exec_ctx *exec_ctx,
+                                    grpc_call_credentials *creds) {
   grpc_composite_call_credentials *c = (grpc_composite_call_credentials *)creds;
   size_t i;
   for (i = 0; i < c->inner.num_creds; i++) {
-    grpc_call_credentials_unref(c->inner.creds_array[i]);
+    grpc_call_credentials_unref(exec_ctx, c->inner.creds_array[i]);
   }
   gpr_free(c->inner.creds_array);
 }
 
 static void composite_call_md_context_destroy(
+    grpc_exec_ctx *exec_ctx,
     grpc_composite_call_credentials_metadata_context *ctx) {
-  grpc_credentials_md_store_unref(ctx->md_elems);
+  grpc_credentials_md_store_unref(exec_ctx, ctx->md_elems);
   gpr_free(ctx);
 }
 
@@ -103,7 +105,7 @@ static void composite_call_metadata_cb(grpc_exec_ctx *exec_ctx, void *user_data,
   /* We're done!. */
   ctx->cb(exec_ctx, ctx->user_data, ctx->md_elems->entries,
           ctx->md_elems->num_entries, GRPC_CREDENTIALS_OK, NULL);
-  composite_call_md_context_destroy(ctx);
+  composite_call_md_context_destroy(exec_ctx, ctx);
 }
 
 static void composite_call_get_request_metadata(
@@ -209,17 +211,19 @@ grpc_call_credentials *grpc_credentials_contains_type(
 
 /* -- Composite channel credentials. -- */
 
-static void composite_channel_destruct(grpc_channel_credentials *creds) {
+static void composite_channel_destruct(grpc_exec_ctx *exec_ctx,
+                                       grpc_channel_credentials *creds) {
   grpc_composite_channel_credentials *c =
       (grpc_composite_channel_credentials *)creds;
-  grpc_channel_credentials_unref(c->inner_creds);
-  grpc_call_credentials_unref(c->call_creds);
+  grpc_channel_credentials_unref(exec_ctx, c->inner_creds);
+  grpc_call_credentials_unref(exec_ctx, c->call_creds);
 }
 
 static grpc_security_status composite_channel_create_security_connector(
-    grpc_channel_credentials *creds, grpc_call_credentials *call_creds,
-    const char *target, const grpc_channel_args *args,
-    grpc_channel_security_connector **sc, grpc_channel_args **new_args) {
+    grpc_exec_ctx *exec_ctx, grpc_channel_credentials *creds,
+    grpc_call_credentials *call_creds, const char *target,
+    const grpc_channel_args *args, grpc_channel_security_connector **sc,
+    grpc_channel_args **new_args) {
   grpc_composite_channel_credentials *c =
       (grpc_composite_channel_credentials *)creds;
   grpc_security_status status = GRPC_SECURITY_ERROR;
@@ -233,11 +237,12 @@ static grpc_security_status composite_channel_create_security_connector(
     grpc_call_credentials *composite_call_creds =
         grpc_composite_call_credentials_create(c->call_creds, call_creds, NULL);
     status = c->inner_creds->vtable->create_security_connector(
-        c->inner_creds, composite_call_creds, target, args, sc, new_args);
-    grpc_call_credentials_unref(composite_call_creds);
+        exec_ctx, c->inner_creds, composite_call_creds, target, args, sc,
+        new_args);
+    grpc_call_credentials_unref(exec_ctx, composite_call_creds);
   } else {
     status = c->inner_creds->vtable->create_security_connector(
-        c->inner_creds, c->call_creds, target, args, sc, new_args);
+        exec_ctx, c->inner_creds, c->call_creds, target, args, sc, new_args);
   }
   return status;
 }
diff --git a/src/core/lib/security/credentials/credentials.c b/src/core/lib/security/credentials/credentials.c
index 1149e5c2ed..9781a22a86 100644
--- a/src/core/lib/security/credentials/credentials.c
+++ b/src/core/lib/security/credentials/credentials.c
@@ -66,8 +66,8 @@ grpc_credentials_metadata_request *grpc_credentials_metadata_request_create(
 }
 
 void grpc_credentials_metadata_request_destroy(
-    grpc_credentials_metadata_request *r) {
-  grpc_call_credentials_unref(r->creds);
+    grpc_exec_ctx *exec_ctx, grpc_credentials_metadata_request *r) {
+  grpc_call_credentials_unref(exec_ctx, r->creds);
   grpc_http_response_destroy(&r->response);
   gpr_free(r);
 }
@@ -79,17 +79,22 @@ grpc_channel_credentials *grpc_channel_credentials_ref(
   return creds;
 }
 
-void grpc_channel_credentials_unref(grpc_channel_credentials *creds) {
+void grpc_channel_credentials_unref(grpc_exec_ctx *exec_ctx,
+                                    grpc_channel_credentials *creds) {
   if (creds == NULL) return;
   if (gpr_unref(&creds->refcount)) {
-    if (creds->vtable->destruct != NULL) creds->vtable->destruct(creds);
+    if (creds->vtable->destruct != NULL) {
+      creds->vtable->destruct(exec_ctx, creds);
+    }
     gpr_free(creds);
   }
 }
 
 void grpc_channel_credentials_release(grpc_channel_credentials *creds) {
   GRPC_API_TRACE("grpc_channel_credentials_release(creds=%p)", 1, (creds));
-  grpc_channel_credentials_unref(creds);
+  grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
+  grpc_channel_credentials_unref(&exec_ctx, creds);
+  grpc_exec_ctx_finish(&exec_ctx);
 }
 
 grpc_call_credentials *grpc_call_credentials_ref(grpc_call_credentials *creds) {
@@ -98,17 +103,22 @@ grpc_call_credentials *grpc_call_credentials_ref(grpc_call_credentials *creds) {
   return creds;
 }
 
-void grpc_call_credentials_unref(grpc_call_credentials *creds) {
+void grpc_call_credentials_unref(grpc_exec_ctx *exec_ctx,
+                                 grpc_call_credentials *creds) {
   if (creds == NULL) return;
   if (gpr_unref(&creds->refcount)) {
-    if (creds->vtable->destruct != NULL) creds->vtable->destruct(creds);
+    if (creds->vtable->destruct != NULL) {
+      creds->vtable->destruct(exec_ctx, creds);
+    }
     gpr_free(creds);
   }
 }
 
 void grpc_call_credentials_release(grpc_call_credentials *creds) {
   GRPC_API_TRACE("grpc_call_credentials_release(creds=%p)", 1, (creds));
-  grpc_call_credentials_unref(creds);
+  grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
+  grpc_call_credentials_unref(&exec_ctx, creds);
+  grpc_exec_ctx_finish(&exec_ctx);
 }
 
 void grpc_call_credentials_get_request_metadata(
@@ -126,16 +136,16 @@ void grpc_call_credentials_get_request_metadata(
 }
 
 grpc_security_status grpc_channel_credentials_create_security_connector(
-    grpc_channel_credentials *channel_creds, const char *target,
-    const grpc_channel_args *args, grpc_channel_security_connector **sc,
-    grpc_channel_args **new_args) {
+    grpc_exec_ctx *exec_ctx, grpc_channel_credentials *channel_creds,
+    const char *target, const grpc_channel_args *args,
+    grpc_channel_security_connector **sc, grpc_channel_args **new_args) {
   *new_args = NULL;
   if (channel_creds == NULL) {
     return GRPC_SECURITY_ERROR;
   }
   GPR_ASSERT(channel_creds->vtable->create_security_connector != NULL);
   return channel_creds->vtable->create_security_connector(
-      channel_creds, NULL, target, args, sc, new_args);
+      exec_ctx, channel_creds, NULL, target, args, sc, new_args);
 }
 
 grpc_channel_credentials *
@@ -157,10 +167,13 @@ grpc_server_credentials *grpc_server_credentials_ref(
   return creds;
 }
 
-void grpc_server_credentials_unref(grpc_server_credentials *creds) {
+void grpc_server_credentials_unref(grpc_exec_ctx *exec_ctx,
+                                   grpc_server_credentials *creds) {
   if (creds == NULL) return;
   if (gpr_unref(&creds->refcount)) {
-    if (creds->vtable->destruct != NULL) creds->vtable->destruct(creds);
+    if (creds->vtable->destruct != NULL) {
+      creds->vtable->destruct(exec_ctx, creds);
+    }
     if (creds->processor.destroy != NULL && creds->processor.state != NULL) {
       creds->processor.destroy(creds->processor.state);
     }
@@ -170,16 +183,19 @@ void grpc_server_credentials_unref(grpc_server_credentials *creds) {
 
 void grpc_server_credentials_release(grpc_server_credentials *creds) {
   GRPC_API_TRACE("grpc_server_credentials_release(creds=%p)", 1, (creds));
-  grpc_server_credentials_unref(creds);
+  grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
+  grpc_server_credentials_unref(&exec_ctx, creds);
+  grpc_exec_ctx_finish(&exec_ctx);
 }
 
 grpc_security_status grpc_server_credentials_create_security_connector(
-    grpc_server_credentials *creds, grpc_server_security_connector **sc) {
+    grpc_exec_ctx *exec_ctx, grpc_server_credentials *creds,
+    grpc_server_security_connector **sc) {
   if (creds == NULL || creds->vtable->create_security_connector == NULL) {
     gpr_log(GPR_ERROR, "Server credentials cannot create security context.");
     return GRPC_SECURITY_ERROR;
   }
-  return creds->vtable->create_security_connector(creds, sc);
+  return creds->vtable->create_security_connector(exec_ctx, creds, sc);
 }
 
 void grpc_server_credentials_set_auth_metadata_processor(
@@ -196,8 +212,9 @@ void grpc_server_credentials_set_auth_metadata_processor(
   creds->processor = processor;
 }
 
-static void server_credentials_pointer_arg_destroy(void *p) {
-  grpc_server_credentials_unref(p);
+static void server_credentials_pointer_arg_destroy(grpc_exec_ctx *exec_ctx,
+                                                   void *p) {
+  grpc_server_credentials_unref(exec_ctx, p);
 }
 
 static void *server_credentials_pointer_arg_copy(void *p) {
diff --git a/src/core/lib/security/credentials/credentials.h b/src/core/lib/security/credentials/credentials.h
index 85b3bc5350..3011df6b8a 100644
--- a/src/core/lib/security/credentials/credentials.h
+++ b/src/core/lib/security/credentials/credentials.h
@@ -101,12 +101,13 @@ void grpc_override_well_known_credentials_path_getter(
 /* --- grpc_channel_credentials. --- */
 
 typedef struct {
-  void (*destruct)(grpc_channel_credentials *c);
+  void (*destruct)(grpc_exec_ctx *exec_ctx, grpc_channel_credentials *c);
 
   grpc_security_status (*create_security_connector)(
-      grpc_channel_credentials *c, grpc_call_credentials *call_creds,
-      const char *target, const grpc_channel_args *args,
-      grpc_channel_security_connector **sc, grpc_channel_args **new_args);
+      grpc_exec_ctx *exec_ctx, grpc_channel_credentials *c,
+      grpc_call_credentials *call_creds, const char *target,
+      const grpc_channel_args *args, grpc_channel_security_connector **sc,
+      grpc_channel_args **new_args);
 
   grpc_channel_credentials *(*duplicate_without_call_credentials)(
       grpc_channel_credentials *c);
@@ -120,16 +121,17 @@ struct grpc_channel_credentials {
 
 grpc_channel_credentials *grpc_channel_credentials_ref(
     grpc_channel_credentials *creds);
-void grpc_channel_credentials_unref(grpc_channel_credentials *creds);
+void grpc_channel_credentials_unref(grpc_exec_ctx *exec_ctx,
+                                    grpc_channel_credentials *creds);
 
 /* Creates a security connector for the channel. May also create new channel
    args for the channel to be used in place of the passed in const args if
    returned non NULL. In that case the caller is responsible for destroying
    new_args after channel creation. */
 grpc_security_status grpc_channel_credentials_create_security_connector(
-    grpc_channel_credentials *creds, const char *target,
-    const grpc_channel_args *args, grpc_channel_security_connector **sc,
-    grpc_channel_args **new_args);
+    grpc_exec_ctx *exec_ctx, grpc_channel_credentials *creds,
+    const char *target, const grpc_channel_args *args,
+    grpc_channel_security_connector **sc, grpc_channel_args **new_args);
 
 /* Creates a version of the channel credentials without any attached call
    credentials. This can be used in order to open a channel to a non-trusted
@@ -162,7 +164,8 @@ void grpc_credentials_md_store_add_cstrings(grpc_credentials_md_store *store,
                                             const char *key, const char *value);
 grpc_credentials_md_store *grpc_credentials_md_store_ref(
     grpc_credentials_md_store *store);
-void grpc_credentials_md_store_unref(grpc_credentials_md_store *store);
+void grpc_credentials_md_store_unref(grpc_exec_ctx *exec_ctx,
+                                     grpc_credentials_md_store *store);
 
 /* --- grpc_call_credentials. --- */
 
@@ -172,7 +175,7 @@ typedef void (*grpc_credentials_metadata_cb)(
     size_t num_md, grpc_credentials_status status, const char *error_details);
 
 typedef struct {
-  void (*destruct)(grpc_call_credentials *c);
+  void (*destruct)(grpc_exec_ctx *exec_ctx, grpc_call_credentials *c);
   void (*get_request_metadata)(grpc_exec_ctx *exec_ctx,
                                grpc_call_credentials *c,
                                grpc_polling_entity *pollent,
@@ -188,7 +191,8 @@ struct grpc_call_credentials {
 };
 
 grpc_call_credentials *grpc_call_credentials_ref(grpc_call_credentials *creds);
-void grpc_call_credentials_unref(grpc_call_credentials *creds);
+void grpc_call_credentials_unref(grpc_exec_ctx *exec_ctx,
+                                 grpc_call_credentials *creds);
 void grpc_call_credentials_get_request_metadata(
     grpc_exec_ctx *exec_ctx, grpc_call_credentials *creds,
     grpc_polling_entity *pollent, grpc_auth_metadata_context context,
@@ -202,9 +206,10 @@ grpc_call_credentials *grpc_md_only_test_credentials_create(
 /* --- grpc_server_credentials. --- */
 
 typedef struct {
-  void (*destruct)(grpc_server_credentials *c);
+  void (*destruct)(grpc_exec_ctx *exec_ctx, grpc_server_credentials *c);
   grpc_security_status (*create_security_connector)(
-      grpc_server_credentials *c, grpc_server_security_connector **sc);
+      grpc_exec_ctx *exec_ctx, grpc_server_credentials *c,
+      grpc_server_security_connector **sc);
 } grpc_server_credentials_vtable;
 
 struct grpc_server_credentials {
@@ -215,12 +220,14 @@ struct grpc_server_credentials {
 };
 
 grpc_security_status grpc_server_credentials_create_security_connector(
-    grpc_server_credentials *creds, grpc_server_security_connector **sc);
+    grpc_exec_ctx *exec_ctx, grpc_server_credentials *creds,
+    grpc_server_security_connector **sc);
 
 grpc_server_credentials *grpc_server_credentials_ref(
     grpc_server_credentials *creds);
 
-void grpc_server_credentials_unref(grpc_server_credentials *creds);
+void grpc_server_credentials_unref(grpc_exec_ctx *exec_ctx,
+                                   grpc_server_credentials *creds);
 
 #define GRPC_SERVER_CREDENTIALS_ARG "grpc.server_credentials"
 
@@ -243,6 +250,6 @@ grpc_credentials_metadata_request *grpc_credentials_metadata_request_create(
     void *user_data);
 
 void grpc_credentials_metadata_request_destroy(
-    grpc_credentials_metadata_request *r);
+    grpc_exec_ctx *exec_ctx, grpc_credentials_metadata_request *r);
 
 #endif /* GRPC_CORE_LIB_SECURITY_CREDENTIALS_CREDENTIALS_H */
diff --git a/src/core/lib/security/credentials/credentials_metadata.c b/src/core/lib/security/credentials/credentials_metadata.c
index e6cb567734..68da5fb4a8 100644
--- a/src/core/lib/security/credentials/credentials_metadata.c
+++ b/src/core/lib/security/credentials/credentials_metadata.c
@@ -37,6 +37,8 @@
 
 #include <string.h>
 
+#include "src/core/lib/slice/slice_internal.h"
+
 static void store_ensure_capacity(grpc_credentials_md_store *store) {
   if (store->num_entries == store->allocated) {
     store->allocated = (store->allocated == 0) ? 1 : store->allocated * 2;
@@ -62,8 +64,8 @@ void grpc_credentials_md_store_add(grpc_credentials_md_store *store,
                                    grpc_slice key, grpc_slice value) {
   if (store == NULL) return;
   store_ensure_capacity(store);
-  store->entries[store->num_entries].key = grpc_slice_ref(key);
-  store->entries[store->num_entries].value = grpc_slice_ref(value);
+  store->entries[store->num_entries].key = grpc_slice_ref_internal(key);
+  store->entries[store->num_entries].value = grpc_slice_ref_internal(value);
   store->num_entries++;
 }
 
@@ -85,14 +87,15 @@ grpc_credentials_md_store *grpc_credentials_md_store_ref(
   return store;
 }
 
-void grpc_credentials_md_store_unref(grpc_credentials_md_store *store) {
+void grpc_credentials_md_store_unref(grpc_exec_ctx *exec_ctx,
+                                     grpc_credentials_md_store *store) {
   if (store == NULL) return;
   if (gpr_unref(&store->refcount)) {
     if (store->entries != NULL) {
       size_t i;
       for (i = 0; i < store->num_entries; i++) {
-        grpc_slice_unref(store->entries[i].key);
-        grpc_slice_unref(store->entries[i].value);
+        grpc_slice_unref_internal(exec_ctx, store->entries[i].key);
+        grpc_slice_unref_internal(exec_ctx, store->entries[i].value);
       }
       gpr_free(store->entries);
     }
diff --git a/src/core/lib/security/credentials/fake/fake_credentials.c b/src/core/lib/security/credentials/fake/fake_credentials.c
index 1cf142fa9a..a8679d097d 100644
--- a/src/core/lib/security/credentials/fake/fake_credentials.c
+++ b/src/core/lib/security/credentials/fake/fake_credentials.c
@@ -45,16 +45,18 @@
 /* -- Fake transport security credentials. -- */
 
 static grpc_security_status fake_transport_security_create_security_connector(
-    grpc_channel_credentials *c, grpc_call_credentials *call_creds,
-    const char *target, const grpc_channel_args *args,
-    grpc_channel_security_connector **sc, grpc_channel_args **new_args) {
+    grpc_exec_ctx *exec_ctx, grpc_channel_credentials *c,
+    grpc_call_credentials *call_creds, const char *target,
+    const grpc_channel_args *args, grpc_channel_security_connector **sc,
+    grpc_channel_args **new_args) {
   *sc = grpc_fake_channel_security_connector_create(call_creds);
   return GRPC_SECURITY_OK;
 }
 
 static grpc_security_status
 fake_transport_security_server_create_security_connector(
-    grpc_server_credentials *c, grpc_server_security_connector **sc) {
+    grpc_exec_ctx *exec_ctx, grpc_server_credentials *c,
+    grpc_server_security_connector **sc) {
   *sc = grpc_fake_server_security_connector_create();
   return GRPC_SECURITY_OK;
 }
@@ -89,9 +91,10 @@ grpc_server_credentials *grpc_fake_transport_security_server_credentials_create(
 
 /* -- Metadata-only test credentials. -- */
 
-static void md_only_test_destruct(grpc_call_credentials *creds) {
+static void md_only_test_destruct(grpc_exec_ctx *exec_ctx,
+                                  grpc_call_credentials *creds) {
   grpc_md_only_test_credentials *c = (grpc_md_only_test_credentials *)creds;
-  grpc_credentials_md_store_unref(c->md_store);
+  grpc_credentials_md_store_unref(exec_ctx, c->md_store);
 }
 
 static void on_simulated_token_fetch_done(grpc_exec_ctx *exec_ctx,
@@ -101,7 +104,7 @@ static void on_simulated_token_fetch_done(grpc_exec_ctx *exec_ctx,
   grpc_md_only_test_credentials *c = (grpc_md_only_test_credentials *)r->creds;
   r->cb(exec_ctx, r->user_data, c->md_store->entries, c->md_store->num_entries,
         GRPC_CREDENTIALS_OK, NULL);
-  grpc_credentials_metadata_request_destroy(r);
+  grpc_credentials_metadata_request_destroy(exec_ctx, r);
 }
 
 static void md_only_test_get_request_metadata(
diff --git a/src/core/lib/security/credentials/google_default/google_default_credentials.c b/src/core/lib/security/credentials/google_default/google_default_credentials.c
index caf57c856b..d6e1fe3dcf 100644
--- a/src/core/lib/security/credentials/google_default/google_default_credentials.c
+++ b/src/core/lib/security/credentials/google_default/google_default_credentials.c
@@ -45,6 +45,7 @@
 #include "src/core/lib/iomgr/polling_entity.h"
 #include "src/core/lib/security/credentials/jwt/jwt_credentials.h"
 #include "src/core/lib/security/credentials/oauth2/oauth2_credentials.h"
+#include "src/core/lib/slice/slice_internal.h"
 #include "src/core/lib/slice/slice_string_helpers.h"
 #include "src/core/lib/support/env.h"
 #include "src/core/lib/support/string.h"
@@ -101,11 +102,10 @@ static void destroy_pollset(grpc_exec_ctx *exec_ctx, void *p, grpc_error *e) {
   grpc_pollset_destroy(p);
 }
 
-static int is_stack_running_on_compute_engine(void) {
+static int is_stack_running_on_compute_engine(grpc_exec_ctx *exec_ctx) {
   compute_engine_detector detector;
   grpc_httpcli_request request;
   grpc_httpcli_context context;
-  grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
   grpc_closure destroy_closure;
 
   /* The http call is local. If it takes more than one sec, it is for sure not
@@ -128,14 +128,14 @@ static int is_stack_running_on_compute_engine(void) {
   grpc_resource_quota *resource_quota =
       grpc_resource_quota_create("google_default_credentials");
   grpc_httpcli_get(
-      &exec_ctx, &context, &detector.pollent, resource_quota, &request,
+      exec_ctx, &context, &detector.pollent, resource_quota, &request,
       gpr_time_add(gpr_now(GPR_CLOCK_REALTIME), max_detection_delay),
       grpc_closure_create(on_compute_engine_detection_http_response, &detector,
                           grpc_schedule_on_exec_ctx),
       &detector.response);
-  grpc_resource_quota_internal_unref(&exec_ctx, resource_quota);
+  grpc_resource_quota_unref_internal(exec_ctx, resource_quota);
 
-  grpc_exec_ctx_flush(&exec_ctx);
+  grpc_exec_ctx_flush(exec_ctx);
 
   /* Block until we get the response. This is not ideal but this should only be
      called once for the lifetime of the process by the default credentials. */
@@ -144,7 +144,7 @@ static int is_stack_running_on_compute_engine(void) {
     grpc_pollset_worker *worker = NULL;
     if (!GRPC_LOG_IF_ERROR(
             "pollset_work",
-            grpc_pollset_work(&exec_ctx,
+            grpc_pollset_work(exec_ctx,
                               grpc_polling_entity_pollset(&detector.pollent),
                               &worker, gpr_now(GPR_CLOCK_MONOTONIC),
                               gpr_inf_future(GPR_CLOCK_MONOTONIC)))) {
@@ -158,11 +158,11 @@ static int is_stack_running_on_compute_engine(void) {
   grpc_closure_init(&destroy_closure, destroy_pollset,
                     grpc_polling_entity_pollset(&detector.pollent),
                     grpc_schedule_on_exec_ctx);
-  grpc_pollset_shutdown(&exec_ctx,
+  grpc_pollset_shutdown(exec_ctx,
                         grpc_polling_entity_pollset(&detector.pollent),
                         &destroy_closure);
-  grpc_exec_ctx_finish(&exec_ctx);
   g_polling_mu = NULL;
+  grpc_exec_ctx_flush(exec_ctx);
 
   gpr_free(grpc_polling_entity_pollset(&detector.pollent));
   grpc_http_response_destroy(&detector.response);
@@ -172,7 +172,7 @@ static int is_stack_running_on_compute_engine(void) {
 
 /* Takes ownership of creds_path if not NULL. */
 static grpc_error *create_default_creds_from_path(
-    char *creds_path, grpc_call_credentials **creds) {
+    grpc_exec_ctx *exec_ctx, char *creds_path, grpc_call_credentials **creds) {
   grpc_json *json = NULL;
   grpc_auth_json_key key;
   grpc_auth_refresh_token token;
@@ -202,7 +202,7 @@ static grpc_error *create_default_creds_from_path(
   if (grpc_auth_json_key_is_valid(&key)) {
     result =
         grpc_service_account_jwt_access_credentials_create_from_auth_json_key(
-            key, grpc_max_auth_token_lifetime());
+            exec_ctx, key, grpc_max_auth_token_lifetime());
     if (result == NULL) {
       error = GRPC_ERROR_CREATE(
           "grpc_service_account_jwt_access_credentials_create_from_auth_json_"
@@ -227,7 +227,7 @@ static grpc_error *create_default_creds_from_path(
 end:
   GPR_ASSERT((result == NULL) + (error == GRPC_ERROR_NONE) == 1);
   if (creds_path != NULL) gpr_free(creds_path);
-  grpc_slice_unref(creds_data);
+  grpc_slice_unref_internal(exec_ctx, creds_data);
   if (json != NULL) grpc_json_destroy(json);
   *creds = result;
   return error;
@@ -238,6 +238,7 @@ grpc_channel_credentials *grpc_google_default_credentials_create(void) {
   grpc_call_credentials *call_creds = NULL;
   grpc_error *error = GRPC_ERROR_CREATE("Failed to create Google credentials");
   grpc_error *err;
+  grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
 
   GRPC_API_TRACE("grpc_google_default_credentials_create(void)", 0, ());
 
@@ -252,20 +253,22 @@ grpc_channel_credentials *grpc_google_default_credentials_create(void) {
 
   /* First, try the environment variable. */
   err = create_default_creds_from_path(
-      gpr_getenv(GRPC_GOOGLE_CREDENTIALS_ENV_VAR), &call_creds);
+      &exec_ctx, gpr_getenv(GRPC_GOOGLE_CREDENTIALS_ENV_VAR), &call_creds);
   if (err == GRPC_ERROR_NONE) goto end;
   error = grpc_error_add_child(error, err);
 
   /* Then the well-known file. */
   err = create_default_creds_from_path(
-      grpc_get_well_known_google_credentials_file_path(), &call_creds);
+      &exec_ctx, grpc_get_well_known_google_credentials_file_path(),
+      &call_creds);
   if (err == GRPC_ERROR_NONE) goto end;
   error = grpc_error_add_child(error, err);
 
   /* At last try to see if we're on compute engine (do the detection only once
      since it requires a network test). */
   if (!compute_engine_detection_done) {
-    int need_compute_engine_creds = is_stack_running_on_compute_engine();
+    int need_compute_engine_creds =
+        is_stack_running_on_compute_engine(&exec_ctx);
     compute_engine_detection_done = 1;
     if (need_compute_engine_creds) {
       call_creds = grpc_google_compute_engine_credentials_create(NULL);
@@ -288,8 +291,8 @@ end:
           grpc_composite_channel_credentials_create(ssl_creds, call_creds,
                                                     NULL));
       GPR_ASSERT(default_credentials != NULL);
-      grpc_channel_credentials_unref(ssl_creds);
-      grpc_call_credentials_unref(call_creds);
+      grpc_channel_credentials_unref(&exec_ctx, ssl_creds);
+      grpc_call_credentials_unref(&exec_ctx, call_creds);
       result = default_credentials;
     } else {
       gpr_log(GPR_ERROR, "Could not create google default credentials.");
@@ -301,18 +304,21 @@ end:
   } else {
     GRPC_ERROR_UNREF(error);
   }
+  grpc_exec_ctx_finish(&exec_ctx);
   return result;
 }
 
 void grpc_flush_cached_google_default_credentials(void) {
+  grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
   gpr_once_init(&g_once, init_default_credentials);
   gpr_mu_lock(&g_state_mu);
   if (default_credentials != NULL) {
-    grpc_channel_credentials_unref(default_credentials);
+    grpc_channel_credentials_unref(&exec_ctx, default_credentials);
     default_credentials = NULL;
   }
   compute_engine_detection_done = 0;
   gpr_mu_unlock(&g_state_mu);
+  grpc_exec_ctx_finish(&exec_ctx);
 }
 
 /* -- Well known credentials path. -- */
diff --git a/src/core/lib/security/credentials/iam/iam_credentials.c b/src/core/lib/security/credentials/iam/iam_credentials.c
index 370a384d0e..abd69a9670 100644
--- a/src/core/lib/security/credentials/iam/iam_credentials.c
+++ b/src/core/lib/security/credentials/iam/iam_credentials.c
@@ -42,9 +42,10 @@
 #include <grpc/support/string_util.h>
 #include <grpc/support/sync.h>
 
-static void iam_destruct(grpc_call_credentials *creds) {
+static void iam_destruct(grpc_exec_ctx *exec_ctx,
+                         grpc_call_credentials *creds) {
   grpc_google_iam_credentials *c = (grpc_google_iam_credentials *)creds;
-  grpc_credentials_md_store_unref(c->iam_md);
+  grpc_credentials_md_store_unref(exec_ctx, c->iam_md);
 }
 
 static void iam_get_request_metadata(grpc_exec_ctx *exec_ctx,
diff --git a/src/core/lib/security/credentials/jwt/jwt_credentials.c b/src/core/lib/security/credentials/jwt/jwt_credentials.c
index 3daf0f4ef7..616be64a54 100644
--- a/src/core/lib/security/credentials/jwt/jwt_credentials.c
+++ b/src/core/lib/security/credentials/jwt/jwt_credentials.c
@@ -42,9 +42,10 @@
 #include <grpc/support/string_util.h>
 #include <grpc/support/sync.h>
 
-static void jwt_reset_cache(grpc_service_account_jwt_access_credentials *c) {
+static void jwt_reset_cache(grpc_exec_ctx *exec_ctx,
+                            grpc_service_account_jwt_access_credentials *c) {
   if (c->cached.jwt_md != NULL) {
-    grpc_credentials_md_store_unref(c->cached.jwt_md);
+    grpc_credentials_md_store_unref(exec_ctx, c->cached.jwt_md);
     c->cached.jwt_md = NULL;
   }
   if (c->cached.service_url != NULL) {
@@ -54,11 +55,12 @@ static void jwt_reset_cache(grpc_service_account_jwt_access_credentials *c) {
   c->cached.jwt_expiration = gpr_inf_past(GPR_CLOCK_REALTIME);
 }
 
-static void jwt_destruct(grpc_call_credentials *creds) {
+static void jwt_destruct(grpc_exec_ctx *exec_ctx,
+                         grpc_call_credentials *creds) {
   grpc_service_account_jwt_access_credentials *c =
       (grpc_service_account_jwt_access_credentials *)creds;
   grpc_auth_json_key_destruct(&c->key);
-  jwt_reset_cache(c);
+  jwt_reset_cache(exec_ctx, c);
   gpr_mu_destroy(&c->cache_mu);
 }
 
@@ -92,7 +94,7 @@ static void jwt_get_request_metadata(grpc_exec_ctx *exec_ctx,
     char *jwt = NULL;
     /* Generate a new jwt. */
     gpr_mu_lock(&c->cache_mu);
-    jwt_reset_cache(c);
+    jwt_reset_cache(exec_ctx, c);
     jwt = grpc_jwt_encode_and_sign(&c->key, context.service_url,
                                    c->jwt_lifetime, NULL);
     if (jwt != NULL) {
@@ -114,7 +116,7 @@ static void jwt_get_request_metadata(grpc_exec_ctx *exec_ctx,
   if (jwt_md != NULL) {
     cb(exec_ctx, user_data, jwt_md->entries, jwt_md->num_entries,
        GRPC_CREDENTIALS_OK, NULL);
-    grpc_credentials_md_store_unref(jwt_md);
+    grpc_credentials_md_store_unref(exec_ctx, jwt_md);
   } else {
     cb(exec_ctx, user_data, NULL, 0, GRPC_CREDENTIALS_ERROR,
        "Could not generate JWT.");
@@ -126,7 +128,8 @@ static grpc_call_credentials_vtable jwt_vtable = {jwt_destruct,
 
 grpc_call_credentials *
 grpc_service_account_jwt_access_credentials_create_from_auth_json_key(
-    grpc_auth_json_key key, gpr_timespec token_lifetime) {
+    grpc_exec_ctx *exec_ctx, grpc_auth_json_key key,
+    gpr_timespec token_lifetime) {
   grpc_service_account_jwt_access_credentials *c;
   if (!grpc_auth_json_key_is_valid(&key)) {
     gpr_log(GPR_ERROR, "Invalid input for jwt credentials creation");
@@ -140,7 +143,7 @@ grpc_service_account_jwt_access_credentials_create_from_auth_json_key(
   c->key = key;
   c->jwt_lifetime = token_lifetime;
   gpr_mu_init(&c->cache_mu);
-  jwt_reset_cache(c);
+  jwt_reset_cache(exec_ctx, c);
   return &c->base;
 }
 
@@ -183,6 +186,11 @@ grpc_call_credentials *grpc_service_account_jwt_access_credentials_create(
     gpr_free(clean_json);
   }
   GPR_ASSERT(reserved == NULL);
-  return grpc_service_account_jwt_access_credentials_create_from_auth_json_key(
-      grpc_auth_json_key_create_from_string(json_key), token_lifetime);
+  grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
+  grpc_call_credentials *creds =
+      grpc_service_account_jwt_access_credentials_create_from_auth_json_key(
+          &exec_ctx, grpc_auth_json_key_create_from_string(json_key),
+          token_lifetime);
+  grpc_exec_ctx_finish(&exec_ctx);
+  return creds;
 }
diff --git a/src/core/lib/security/credentials/jwt/jwt_credentials.h b/src/core/lib/security/credentials/jwt/jwt_credentials.h
index d572606179..39b7aeafe8 100644
--- a/src/core/lib/security/credentials/jwt/jwt_credentials.h
+++ b/src/core/lib/security/credentials/jwt/jwt_credentials.h
@@ -57,6 +57,7 @@ typedef struct {
 // Takes ownership of the key.
 grpc_call_credentials *
 grpc_service_account_jwt_access_credentials_create_from_auth_json_key(
-    grpc_auth_json_key key, gpr_timespec token_lifetime);
+    grpc_exec_ctx *exec_ctx, grpc_auth_json_key key,
+    gpr_timespec token_lifetime);
 
 #endif /* GRPC_CORE_LIB_SECURITY_CREDENTIALS_JWT_JWT_CREDENTIALS_H */
diff --git a/src/core/lib/security/credentials/jwt/jwt_verifier.c b/src/core/lib/security/credentials/jwt/jwt_verifier.c
index 8c75098612..2270be8f44 100644
--- a/src/core/lib/security/credentials/jwt/jwt_verifier.c
+++ b/src/core/lib/security/credentials/jwt/jwt_verifier.c
@@ -36,12 +36,6 @@
 #include <limits.h>
 #include <string.h>
 
-#include "src/core/lib/http/httpcli.h"
-#include "src/core/lib/iomgr/polling_entity.h"
-#include "src/core/lib/security/util/b64.h"
-#include "src/core/lib/support/string.h"
-#include "src/core/lib/tsi/ssl_types.h"
-
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
 #include <grpc/support/string_util.h>
@@ -49,6 +43,13 @@
 #include <grpc/support/useful.h>
 #include <openssl/pem.h>
 
+#include "src/core/lib/http/httpcli.h"
+#include "src/core/lib/iomgr/polling_entity.h"
+#include "src/core/lib/security/util/b64.h"
+#include "src/core/lib/slice/slice_internal.h"
+#include "src/core/lib/support/string.h"
+#include "src/core/lib/tsi/ssl_types.h"
+
 /* --- Utils. --- */
 
 const char *grpc_jwt_verifier_status_to_string(
@@ -85,11 +86,12 @@ static const EVP_MD *evp_md_from_alg(const char *alg) {
   }
 }
 
-static grpc_json *parse_json_part_from_jwt(const char *str, size_t len,
+static grpc_json *parse_json_part_from_jwt(grpc_exec_ctx *exec_ctx,
+                                           const char *str, size_t len,
                                            grpc_slice *buffer) {
   grpc_json *json;
 
-  *buffer = grpc_base64_decode_with_len(str, len, 1);
+  *buffer = grpc_base64_decode_with_len(exec_ctx, str, len, 1);
   if (GRPC_SLICE_IS_EMPTY(*buffer)) {
     gpr_log(GPR_ERROR, "Invalid base64.");
     return NULL;
@@ -97,7 +99,7 @@ static grpc_json *parse_json_part_from_jwt(const char *str, size_t len,
   json = grpc_json_parse_string_with_len((char *)GRPC_SLICE_START_PTR(*buffer),
                                          GRPC_SLICE_LENGTH(*buffer));
   if (json == NULL) {
-    grpc_slice_unref(*buffer);
+    grpc_slice_unref_internal(exec_ctx, *buffer);
     gpr_log(GPR_ERROR, "JSON parsing error.");
   }
   return json;
@@ -133,13 +135,14 @@ typedef struct {
   grpc_slice buffer;
 } jose_header;
 
-static void jose_header_destroy(jose_header *h) {
-  grpc_slice_unref(h->buffer);
+static void jose_header_destroy(grpc_exec_ctx *exec_ctx, jose_header *h) {
+  grpc_slice_unref_internal(exec_ctx, h->buffer);
   gpr_free(h);
 }
 
 /* Takes ownership of json and buffer. */
-static jose_header *jose_header_from_json(grpc_json *json, grpc_slice buffer) {
+static jose_header *jose_header_from_json(grpc_exec_ctx *exec_ctx,
+                                          grpc_json *json, grpc_slice buffer) {
   grpc_json *cur;
   jose_header *h = gpr_malloc(sizeof(jose_header));
   memset(h, 0, sizeof(jose_header));
@@ -174,7 +177,7 @@ static jose_header *jose_header_from_json(grpc_json *json, grpc_slice buffer) {
 
 error:
   grpc_json_destroy(json);
-  jose_header_destroy(h);
+  jose_header_destroy(exec_ctx, h);
   return NULL;
 }
 
@@ -194,9 +197,9 @@ struct grpc_jwt_claims {
   grpc_slice buffer;
 };
 
-void grpc_jwt_claims_destroy(grpc_jwt_claims *claims) {
+void grpc_jwt_claims_destroy(grpc_exec_ctx *exec_ctx, grpc_jwt_claims *claims) {
   grpc_json_destroy(claims->json);
-  grpc_slice_unref(claims->buffer);
+  grpc_slice_unref_internal(exec_ctx, claims->buffer);
   gpr_free(claims);
 }
 
@@ -241,7 +244,8 @@ gpr_timespec grpc_jwt_claims_not_before(const grpc_jwt_claims *claims) {
 }
 
 /* Takes ownership of json and buffer even in case of failure. */
-grpc_jwt_claims *grpc_jwt_claims_from_json(grpc_json *json, grpc_slice buffer) {
+grpc_jwt_claims *grpc_jwt_claims_from_json(grpc_exec_ctx *exec_ctx,
+                                           grpc_json *json, grpc_slice buffer) {
   grpc_json *cur;
   grpc_jwt_claims *claims = gpr_malloc(sizeof(grpc_jwt_claims));
   memset(claims, 0, sizeof(grpc_jwt_claims));
@@ -282,7 +286,7 @@ grpc_jwt_claims *grpc_jwt_claims_from_json(grpc_json *json, grpc_slice buffer) {
   return claims;
 
 error:
-  grpc_jwt_claims_destroy(claims);
+  grpc_jwt_claims_destroy(exec_ctx, claims);
   return NULL;
 }
 
@@ -374,12 +378,12 @@ static verifier_cb_ctx *verifier_cb_ctx_create(
   return ctx;
 }
 
-void verifier_cb_ctx_destroy(verifier_cb_ctx *ctx) {
+void verifier_cb_ctx_destroy(grpc_exec_ctx *exec_ctx, verifier_cb_ctx *ctx) {
   if (ctx->audience != NULL) gpr_free(ctx->audience);
-  if (ctx->claims != NULL) grpc_jwt_claims_destroy(ctx->claims);
-  grpc_slice_unref(ctx->signature);
-  grpc_slice_unref(ctx->signed_data);
-  jose_header_destroy(ctx->header);
+  if (ctx->claims != NULL) grpc_jwt_claims_destroy(exec_ctx, ctx->claims);
+  grpc_slice_unref_internal(exec_ctx, ctx->signature);
+  grpc_slice_unref_internal(exec_ctx, ctx->signed_data);
+  jose_header_destroy(exec_ctx, ctx->header);
   for (size_t i = 0; i < HTTP_RESPONSE_COUNT; i++) {
     grpc_http_response_destroy(&ctx->responses[i]);
   }
@@ -459,23 +463,24 @@ end:
   return result;
 }
 
-static BIGNUM *bignum_from_base64(const char *b64) {
+static BIGNUM *bignum_from_base64(grpc_exec_ctx *exec_ctx, const char *b64) {
   BIGNUM *result = NULL;
   grpc_slice bin;
 
   if (b64 == NULL) return NULL;
-  bin = grpc_base64_decode(b64, 1);
+  bin = grpc_base64_decode(exec_ctx, b64, 1);
   if (GRPC_SLICE_IS_EMPTY(bin)) {
     gpr_log(GPR_ERROR, "Invalid base64 for big num.");
     return NULL;
   }
   result = BN_bin2bn(GRPC_SLICE_START_PTR(bin),
                      TSI_SIZE_AS_SIZE(GRPC_SLICE_LENGTH(bin)), NULL);
-  grpc_slice_unref(bin);
+  grpc_slice_unref_internal(exec_ctx, bin);
   return result;
 }
 
-static EVP_PKEY *pkey_from_jwk(const grpc_json *json, const char *kty) {
+static EVP_PKEY *pkey_from_jwk(grpc_exec_ctx *exec_ctx, const grpc_json *json,
+                               const char *kty) {
   const grpc_json *key_prop;
   RSA *rsa = NULL;
   EVP_PKEY *result = NULL;
@@ -492,10 +497,12 @@ static EVP_PKEY *pkey_from_jwk(const grpc_json *json, const char *kty) {
   }
   for (key_prop = json->child; key_prop != NULL; key_prop = key_prop->next) {
     if (strcmp(key_prop->key, "n") == 0) {
-      rsa->n = bignum_from_base64(validate_string_field(key_prop, "n"));
+      rsa->n =
+          bignum_from_base64(exec_ctx, validate_string_field(key_prop, "n"));
       if (rsa->n == NULL) goto end;
     } else if (strcmp(key_prop->key, "e") == 0) {
-      rsa->e = bignum_from_base64(validate_string_field(key_prop, "e"));
+      rsa->e =
+          bignum_from_base64(exec_ctx, validate_string_field(key_prop, "e"));
       if (rsa->e == NULL) goto end;
     }
   }
@@ -511,7 +518,8 @@ end:
   return result;
 }
 
-static EVP_PKEY *find_verification_key(const grpc_json *json,
+static EVP_PKEY *find_verification_key(grpc_exec_ctx *exec_ctx,
+                                       const grpc_json *json,
                                        const char *header_alg,
                                        const char *header_kid) {
   const grpc_json *jkey;
@@ -555,7 +563,7 @@ static EVP_PKEY *find_verification_key(const grpc_json *json,
     }
     if (alg != NULL && kid != NULL && kty != NULL &&
         strcmp(kid, header_kid) == 0 && strcmp(alg, header_alg) == 0) {
-      return pkey_from_jwk(jkey, kty);
+      return pkey_from_jwk(exec_ctx, jkey, kty);
     }
   }
   gpr_log(GPR_ERROR,
@@ -609,7 +617,7 @@ static void on_keys_retrieved(grpc_exec_ctx *exec_ctx, void *user_data,
     goto end;
   }
   verification_key =
-      find_verification_key(json, ctx->header->alg, ctx->header->kid);
+      find_verification_key(exec_ctx, json, ctx->header->alg, ctx->header->kid);
   if (verification_key == NULL) {
     gpr_log(GPR_ERROR, "Could not find verification key with kid %s.",
             ctx->header->kid);
@@ -633,8 +641,8 @@ static void on_keys_retrieved(grpc_exec_ctx *exec_ctx, void *user_data,
 end:
   if (json != NULL) grpc_json_destroy(json);
   if (verification_key != NULL) EVP_PKEY_free(verification_key);
-  ctx->user_cb(ctx->user_data, status, claims);
-  verifier_cb_ctx_destroy(ctx);
+  ctx->user_cb(exec_ctx, ctx->user_data, status, claims);
+  verifier_cb_ctx_destroy(exec_ctx, ctx);
 }
 
 static void on_openid_config_retrieved(grpc_exec_ctx *exec_ctx, void *user_data,
@@ -679,15 +687,16 @@ static void on_openid_config_retrieved(grpc_exec_ctx *exec_ctx, void *user_data,
       gpr_time_add(gpr_now(GPR_CLOCK_REALTIME), grpc_jwt_verifier_max_delay),
       grpc_closure_create(on_keys_retrieved, ctx, grpc_schedule_on_exec_ctx),
       &ctx->responses[HTTP_RESPONSE_KEYS]);
-  grpc_resource_quota_internal_unref(exec_ctx, resource_quota);
+  grpc_resource_quota_unref_internal(exec_ctx, resource_quota);
   grpc_json_destroy(json);
   gpr_free(req.host);
   return;
 
 error:
   if (json != NULL) grpc_json_destroy(json);
-  ctx->user_cb(ctx->user_data, GRPC_JWT_VERIFIER_KEY_RETRIEVAL_ERROR, NULL);
-  verifier_cb_ctx_destroy(ctx);
+  ctx->user_cb(exec_ctx, ctx->user_data, GRPC_JWT_VERIFIER_KEY_RETRIEVAL_ERROR,
+               NULL);
+  verifier_cb_ctx_destroy(exec_ctx, ctx);
 }
 
 static email_key_mapping *verifier_get_mapping(grpc_jwt_verifier *v,
@@ -805,14 +814,15 @@ static void retrieve_key_and_verify(grpc_exec_ctx *exec_ctx,
       exec_ctx, &ctx->verifier->http_ctx, &ctx->pollent, resource_quota, &req,
       gpr_time_add(gpr_now(GPR_CLOCK_REALTIME), grpc_jwt_verifier_max_delay),
       http_cb, &ctx->responses[rsp_idx]);
-  grpc_resource_quota_internal_unref(exec_ctx, resource_quota);
+  grpc_resource_quota_unref_internal(exec_ctx, resource_quota);
   gpr_free(req.host);
   gpr_free(req.http.path);
   return;
 
 error:
-  ctx->user_cb(ctx->user_data, GRPC_JWT_VERIFIER_KEY_RETRIEVAL_ERROR, NULL);
-  verifier_cb_ctx_destroy(ctx);
+  ctx->user_cb(exec_ctx, ctx->user_data, GRPC_JWT_VERIFIER_KEY_RETRIEVAL_ERROR,
+               NULL);
+  verifier_cb_ctx_destroy(exec_ctx, ctx);
 }
 
 void grpc_jwt_verifier_verify(grpc_exec_ctx *exec_ctx,
@@ -834,22 +844,24 @@ void grpc_jwt_verifier_verify(grpc_exec_ctx *exec_ctx,
   GPR_ASSERT(verifier != NULL && jwt != NULL && audience != NULL && cb != NULL);
   dot = strchr(cur, '.');
   if (dot == NULL) goto error;
-  json = parse_json_part_from_jwt(cur, (size_t)(dot - cur), &header_buffer);
+  json = parse_json_part_from_jwt(exec_ctx, cur, (size_t)(dot - cur),
+                                  &header_buffer);
   if (json == NULL) goto error;
-  header = jose_header_from_json(json, header_buffer);
+  header = jose_header_from_json(exec_ctx, json, header_buffer);
   if (header == NULL) goto error;
 
   cur = dot + 1;
   dot = strchr(cur, '.');
   if (dot == NULL) goto error;
-  json = parse_json_part_from_jwt(cur, (size_t)(dot - cur), &claims_buffer);
+  json = parse_json_part_from_jwt(exec_ctx, cur, (size_t)(dot - cur),
+                                  &claims_buffer);
   if (json == NULL) goto error;
-  claims = grpc_jwt_claims_from_json(json, claims_buffer);
+  claims = grpc_jwt_claims_from_json(exec_ctx, json, claims_buffer);
   if (claims == NULL) goto error;
 
   signed_jwt_len = (size_t)(dot - jwt);
   cur = dot + 1;
-  signature = grpc_base64_decode(cur, 1);
+  signature = grpc_base64_decode(exec_ctx, cur, 1);
   if (GRPC_SLICE_IS_EMPTY(signature)) goto error;
   retrieve_key_and_verify(
       exec_ctx,
@@ -858,9 +870,9 @@ void grpc_jwt_verifier_verify(grpc_exec_ctx *exec_ctx,
   return;
 
 error:
-  if (header != NULL) jose_header_destroy(header);
-  if (claims != NULL) grpc_jwt_claims_destroy(claims);
-  cb(user_data, GRPC_JWT_VERIFIER_BAD_FORMAT, NULL);
+  if (header != NULL) jose_header_destroy(exec_ctx, header);
+  if (claims != NULL) grpc_jwt_claims_destroy(exec_ctx, claims);
+  cb(exec_ctx, user_data, GRPC_JWT_VERIFIER_BAD_FORMAT, NULL);
 }
 
 grpc_jwt_verifier *grpc_jwt_verifier_create(
diff --git a/src/core/lib/security/credentials/jwt/jwt_verifier.h b/src/core/lib/security/credentials/jwt/jwt_verifier.h
index 54ff9b05e5..4fa320a415 100644
--- a/src/core/lib/security/credentials/jwt/jwt_verifier.h
+++ b/src/core/lib/security/credentials/jwt/jwt_verifier.h
@@ -66,7 +66,7 @@ const char *grpc_jwt_verifier_status_to_string(grpc_jwt_verifier_status status);
 
 typedef struct grpc_jwt_claims grpc_jwt_claims;
 
-void grpc_jwt_claims_destroy(grpc_jwt_claims *claims);
+void grpc_jwt_claims_destroy(grpc_exec_ctx *exec_ctx, grpc_jwt_claims *claims);
 
 /* Returns the whole JSON tree of the claims. */
 const grpc_json *grpc_jwt_claims_json(const grpc_jwt_claims *claims);
@@ -115,7 +115,8 @@ void grpc_jwt_verifier_destroy(grpc_jwt_verifier *verifier);
    is done (maybe in another thread).
    It is the responsibility of the callee to call grpc_jwt_claims_destroy on
    the claims. */
-typedef void (*grpc_jwt_verification_done_cb)(void *user_data,
+typedef void (*grpc_jwt_verification_done_cb)(grpc_exec_ctx *exec_ctx,
+                                              void *user_data,
                                               grpc_jwt_verifier_status status,
                                               grpc_jwt_claims *claims);
 
@@ -129,7 +130,8 @@ void grpc_jwt_verifier_verify(grpc_exec_ctx *exec_ctx,
 
 /* --- TESTING ONLY exposed functions. --- */
 
-grpc_jwt_claims *grpc_jwt_claims_from_json(grpc_json *json, grpc_slice buffer);
+grpc_jwt_claims *grpc_jwt_claims_from_json(grpc_exec_ctx *exec_ctx,
+                                           grpc_json *json, grpc_slice buffer);
 grpc_jwt_verifier_status grpc_jwt_claims_check(const grpc_jwt_claims *claims,
                                                const char *audience);
 const char *grpc_jwt_issuer_email_domain(const char *issuer);
diff --git a/src/core/lib/security/credentials/oauth2/oauth2_credentials.c b/src/core/lib/security/credentials/oauth2/oauth2_credentials.c
index 9aa7863977..1b0e43a1e4 100644
--- a/src/core/lib/security/credentials/oauth2/oauth2_credentials.c
+++ b/src/core/lib/security/credentials/oauth2/oauth2_credentials.c
@@ -118,18 +118,19 @@ void grpc_auth_refresh_token_destruct(grpc_auth_refresh_token *refresh_token) {
 // Oauth2 Token Fetcher credentials.
 //
 
-static void oauth2_token_fetcher_destruct(grpc_call_credentials *creds) {
+static void oauth2_token_fetcher_destruct(grpc_exec_ctx *exec_ctx,
+                                          grpc_call_credentials *creds) {
   grpc_oauth2_token_fetcher_credentials *c =
       (grpc_oauth2_token_fetcher_credentials *)creds;
-  grpc_credentials_md_store_unref(c->access_token_md);
+  grpc_credentials_md_store_unref(exec_ctx, c->access_token_md);
   gpr_mu_destroy(&c->mu);
   grpc_httpcli_context_destroy(&c->httpcli_context);
 }
 
 grpc_credentials_status
 grpc_oauth2_token_fetcher_credentials_parse_server_response(
-    const grpc_http_response *response, grpc_credentials_md_store **token_md,
-    gpr_timespec *token_lifetime) {
+    grpc_exec_ctx *exec_ctx, const grpc_http_response *response,
+    grpc_credentials_md_store **token_md, gpr_timespec *token_lifetime) {
   char *null_terminated_body = NULL;
   char *new_access_token = NULL;
   grpc_credentials_status status = GRPC_CREDENTIALS_OK;
@@ -198,7 +199,7 @@ grpc_oauth2_token_fetcher_credentials_parse_server_response(
     token_lifetime->tv_sec = strtol(expires_in->value, NULL, 10);
     token_lifetime->tv_nsec = 0;
     token_lifetime->clock_type = GPR_TIMESPAN;
-    if (*token_md != NULL) grpc_credentials_md_store_unref(*token_md);
+    if (*token_md != NULL) grpc_credentials_md_store_unref(exec_ctx, *token_md);
     *token_md = grpc_credentials_md_store_create(1);
     grpc_credentials_md_store_add_cstrings(
         *token_md, GRPC_AUTHORIZATION_METADATA_KEY, new_access_token);
@@ -207,7 +208,7 @@ grpc_oauth2_token_fetcher_credentials_parse_server_response(
 
 end:
   if (status != GRPC_CREDENTIALS_OK && (*token_md != NULL)) {
-    grpc_credentials_md_store_unref(*token_md);
+    grpc_credentials_md_store_unref(exec_ctx, *token_md);
     *token_md = NULL;
   }
   if (null_terminated_body != NULL) gpr_free(null_terminated_body);
@@ -230,7 +231,7 @@ static void on_oauth2_token_fetcher_http_response(grpc_exec_ctx *exec_ctx,
 
   gpr_mu_lock(&c->mu);
   status = grpc_oauth2_token_fetcher_credentials_parse_server_response(
-      &r->response, &c->access_token_md, &token_lifetime);
+      exec_ctx, &r->response, &c->access_token_md, &token_lifetime);
   if (status == GRPC_CREDENTIALS_OK) {
     c->token_expiration =
         gpr_time_add(gpr_now(GPR_CLOCK_REALTIME), token_lifetime);
@@ -242,7 +243,7 @@ static void on_oauth2_token_fetcher_http_response(grpc_exec_ctx *exec_ctx,
           "Error occured when fetching oauth2 token.");
   }
   gpr_mu_unlock(&c->mu);
-  grpc_credentials_metadata_request_destroy(r);
+  grpc_credentials_metadata_request_destroy(exec_ctx, r);
 }
 
 static void oauth2_token_fetcher_get_request_metadata(
@@ -268,7 +269,7 @@ static void oauth2_token_fetcher_get_request_metadata(
   if (cached_access_token_md != NULL) {
     cb(exec_ctx, user_data, cached_access_token_md->entries,
        cached_access_token_md->num_entries, GRPC_CREDENTIALS_OK, NULL);
-    grpc_credentials_md_store_unref(cached_access_token_md);
+    grpc_credentials_md_store_unref(exec_ctx, cached_access_token_md);
   } else {
     c->fetch_func(
         exec_ctx,
@@ -315,8 +316,9 @@ static void compute_engine_fetch_oauth2(
   grpc_httpcli_get(
       exec_ctx, httpcli_context, pollent, resource_quota, &request, deadline,
       grpc_closure_create(response_cb, metadata_req, grpc_schedule_on_exec_ctx),
+
       &metadata_req->response);
-  grpc_resource_quota_internal_unref(exec_ctx, resource_quota);
+  grpc_resource_quota_unref_internal(exec_ctx, resource_quota);
 }
 
 grpc_call_credentials *grpc_google_compute_engine_credentials_create(
@@ -335,11 +337,12 @@ grpc_call_credentials *grpc_google_compute_engine_credentials_create(
 // Google Refresh Token credentials.
 //
 
-static void refresh_token_destruct(grpc_call_credentials *creds) {
+static void refresh_token_destruct(grpc_exec_ctx *exec_ctx,
+                                   grpc_call_credentials *creds) {
   grpc_google_refresh_token_credentials *c =
       (grpc_google_refresh_token_credentials *)creds;
   grpc_auth_refresh_token_destruct(&c->refresh_token);
-  oauth2_token_fetcher_destruct(&c->base.base);
+  oauth2_token_fetcher_destruct(exec_ctx, &c->base.base);
 }
 
 static grpc_call_credentials_vtable refresh_token_vtable = {
@@ -374,7 +377,7 @@ static void refresh_token_fetch_oauth2(
       strlen(body), deadline,
       grpc_closure_create(response_cb, metadata_req, grpc_schedule_on_exec_ctx),
       &metadata_req->response);
-  grpc_resource_quota_internal_unref(exec_ctx, resource_quota);
+  grpc_resource_quota_unref_internal(exec_ctx, resource_quota);
   gpr_free(body);
 }
 
@@ -426,9 +429,10 @@ grpc_call_credentials *grpc_google_refresh_token_credentials_create(
 // Oauth2 Access Token credentials.
 //
 
-static void access_token_destruct(grpc_call_credentials *creds) {
+static void access_token_destruct(grpc_exec_ctx *exec_ctx,
+                                  grpc_call_credentials *creds) {
   grpc_access_token_credentials *c = (grpc_access_token_credentials *)creds;
-  grpc_credentials_md_store_unref(c->access_token_md);
+  grpc_credentials_md_store_unref(exec_ctx, c->access_token_md);
 }
 
 static void access_token_get_request_metadata(
diff --git a/src/core/lib/security/credentials/oauth2/oauth2_credentials.h b/src/core/lib/security/credentials/oauth2/oauth2_credentials.h
index 7f6f205c22..2d7c02ccf5 100644
--- a/src/core/lib/security/credentials/oauth2/oauth2_credentials.h
+++ b/src/core/lib/security/credentials/oauth2/oauth2_credentials.h
@@ -103,7 +103,7 @@ grpc_refresh_token_credentials_create_from_auth_refresh_token(
 // Exposed for testing only.
 grpc_credentials_status
 grpc_oauth2_token_fetcher_credentials_parse_server_response(
-    const struct grpc_http_response *response,
+    grpc_exec_ctx *exec_ctx, const struct grpc_http_response *response,
     grpc_credentials_md_store **token_md, gpr_timespec *token_lifetime);
 
 #endif /* GRPC_CORE_LIB_SECURITY_CREDENTIALS_OAUTH2_OAUTH2_CREDENTIALS_H */
diff --git a/src/core/lib/security/credentials/plugin/plugin_credentials.c b/src/core/lib/security/credentials/plugin/plugin_credentials.c
index 5d950098a0..f90d7dce83 100644
--- a/src/core/lib/security/credentials/plugin/plugin_credentials.c
+++ b/src/core/lib/security/credentials/plugin/plugin_credentials.c
@@ -35,20 +35,22 @@
 
 #include <string.h>
 
-#include "src/core/lib/surface/api_trace.h"
-
 #include <grpc/grpc.h>
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
 #include <grpc/support/string_util.h>
 #include <grpc/support/sync.h>
 
+#include "src/core/lib/slice/slice_internal.h"
+#include "src/core/lib/surface/api_trace.h"
+
 typedef struct {
   void *user_data;
   grpc_credentials_metadata_cb cb;
 } grpc_metadata_plugin_request;
 
-static void plugin_destruct(grpc_call_credentials *creds) {
+static void plugin_destruct(grpc_exec_ctx *exec_ctx,
+                            grpc_call_credentials *creds) {
   grpc_plugin_credentials *c = (grpc_plugin_credentials *)creds;
   if (c->plugin.state != NULL && c->plugin.destroy != NULL) {
     c->plugin.destroy(c->plugin.state);
@@ -100,8 +102,8 @@ static void plugin_md_request_metadata_ready(void *request,
       r->cb(&exec_ctx, r->user_data, md_array, num_md, GRPC_CREDENTIALS_OK,
             NULL);
       for (i = 0; i < num_md; i++) {
-        grpc_slice_unref(md_array[i].key);
-        grpc_slice_unref(md_array[i].value);
+        grpc_slice_unref_internal(&exec_ctx, md_array[i].key);
+        grpc_slice_unref_internal(&exec_ctx, md_array[i].value);
       }
       gpr_free(md_array);
     } else if (num_md == 0) {
diff --git a/src/core/lib/security/credentials/ssl/ssl_credentials.c b/src/core/lib/security/credentials/ssl/ssl_credentials.c
index 0dc1fccec4..4eebb7d613 100644
--- a/src/core/lib/security/credentials/ssl/ssl_credentials.c
+++ b/src/core/lib/security/credentials/ssl/ssl_credentials.c
@@ -57,7 +57,8 @@ static void ssl_copy_key_material(const char *input, unsigned char **output,
 // SSL Channel Credentials.
 //
 
-static void ssl_destruct(grpc_channel_credentials *creds) {
+static void ssl_destruct(grpc_exec_ctx *exec_ctx,
+                         grpc_channel_credentials *creds) {
   grpc_ssl_credentials *c = (grpc_ssl_credentials *)creds;
   if (c->config.pem_root_certs != NULL) gpr_free(c->config.pem_root_certs);
   if (c->config.pem_private_key != NULL) gpr_free(c->config.pem_private_key);
@@ -65,9 +66,10 @@ static void ssl_destruct(grpc_channel_credentials *creds) {
 }
 
 static grpc_security_status ssl_create_security_connector(
-    grpc_channel_credentials *creds, grpc_call_credentials *call_creds,
-    const char *target, const grpc_channel_args *args,
-    grpc_channel_security_connector **sc, grpc_channel_args **new_args) {
+    grpc_exec_ctx *exec_ctx, grpc_channel_credentials *creds,
+    grpc_call_credentials *call_creds, const char *target,
+    const grpc_channel_args *args, grpc_channel_security_connector **sc,
+    grpc_channel_args **new_args) {
   grpc_ssl_credentials *c = (grpc_ssl_credentials *)creds;
   grpc_security_status status = GRPC_SECURITY_OK;
   size_t i = 0;
@@ -83,7 +85,7 @@ static grpc_security_status ssl_create_security_connector(
     }
   }
   status = grpc_ssl_channel_security_connector_create(
-      call_creds, &c->config, target, overridden_target_name, sc);
+      exec_ctx, call_creds, &c->config, target, overridden_target_name, sc);
   if (status != GRPC_SECURITY_OK) {
     return status;
   }
@@ -138,7 +140,8 @@ grpc_channel_credentials *grpc_ssl_credentials_create(
 // SSL Server Credentials.
 //
 
-static void ssl_server_destruct(grpc_server_credentials *creds) {
+static void ssl_server_destruct(grpc_exec_ctx *exec_ctx,
+                                grpc_server_credentials *creds) {
   grpc_ssl_server_credentials *c = (grpc_ssl_server_credentials *)creds;
   size_t i;
   for (i = 0; i < c->config.num_key_cert_pairs; i++) {
@@ -161,9 +164,10 @@ static void ssl_server_destruct(grpc_server_credentials *creds) {
 }
 
 static grpc_security_status ssl_server_create_security_connector(
-    grpc_server_credentials *creds, grpc_server_security_connector **sc) {
+    grpc_exec_ctx *exec_ctx, grpc_server_credentials *creds,
+    grpc_server_security_connector **sc) {
   grpc_ssl_server_credentials *c = (grpc_ssl_server_credentials *)creds;
-  return grpc_ssl_server_security_connector_create(&c->config, sc);
+  return grpc_ssl_server_security_connector_create(exec_ctx, &c->config, sc);
 }
 
 static grpc_server_credentials_vtable ssl_server_vtable = {
diff --git a/src/core/lib/security/transport/client_auth_filter.c b/src/core/lib/security/transport/client_auth_filter.c
index da897296e4..b7f6fd23e3 100644
--- a/src/core/lib/security/transport/client_auth_filter.c
+++ b/src/core/lib/security/transport/client_auth_filter.c
@@ -44,6 +44,7 @@
 #include "src/core/lib/security/context/security_context.h"
 #include "src/core/lib/security/credentials/credentials.h"
 #include "src/core/lib/security/transport/security_connector.h"
+#include "src/core/lib/slice/slice_internal.h"
 #include "src/core/lib/support/string.h"
 #include "src/core/lib/surface/call.h"
 #include "src/core/lib/transport/static_metadata.h"
@@ -93,7 +94,8 @@ static void bubble_up_error(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
   call_data *calld = elem->call_data;
   gpr_log(GPR_ERROR, "Client side authentication failure: %s", error_msg);
   grpc_slice error_slice = grpc_slice_from_copied_string(error_msg);
-  grpc_transport_stream_op_add_close(&calld->op, status, &error_slice);
+  grpc_transport_stream_op_add_close(exec_ctx, &calld->op, status,
+                                     &error_slice);
   grpc_call_next_op(exec_ctx, elem, &calld->op);
 }
 
@@ -121,8 +123,9 @@ static void on_credentials_metadata(grpc_exec_ctx *exec_ctx, void *user_data,
   for (i = 0; i < num_md; i++) {
     grpc_metadata_batch_add_tail(
         mdb, &calld->md_links[i],
-        grpc_mdelem_from_slices(grpc_slice_ref(md_elems[i].key),
-                                grpc_slice_ref(md_elems[i].value)));
+        grpc_mdelem_from_slices(exec_ctx,
+                                grpc_slice_ref_internal(md_elems[i].key),
+                                grpc_slice_ref_internal(md_elems[i].value)));
   }
   grpc_call_next_op(exec_ctx, elem, op);
 }
@@ -248,10 +251,10 @@ static void auth_start_transport_op(grpc_exec_ctx *exec_ctx,
       /* Pointer comparison is OK for md_elems created from the same context.
        */
       if (md->key == GRPC_MDSTR_AUTHORITY) {
-        if (calld->host != NULL) GRPC_MDSTR_UNREF(calld->host);
+        if (calld->host != NULL) GRPC_MDSTR_UNREF(exec_ctx, calld->host);
         calld->host = GRPC_MDSTR_REF(md->value);
       } else if (md->key == GRPC_MDSTR_PATH) {
-        if (calld->method != NULL) GRPC_MDSTR_UNREF(calld->method);
+        if (calld->method != NULL) GRPC_MDSTR_UNREF(exec_ctx, calld->method);
         calld->method = GRPC_MDSTR_REF(md->value);
       }
     }
@@ -292,12 +295,12 @@ static void destroy_call_elem(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
                               const grpc_call_final_info *final_info,
                               void *ignored) {
   call_data *calld = elem->call_data;
-  grpc_call_credentials_unref(calld->creds);
+  grpc_call_credentials_unref(exec_ctx, calld->creds);
   if (calld->host != NULL) {
-    GRPC_MDSTR_UNREF(calld->host);
+    GRPC_MDSTR_UNREF(exec_ctx, calld->host);
   }
   if (calld->method != NULL) {
-    GRPC_MDSTR_UNREF(calld->method);
+    GRPC_MDSTR_UNREF(exec_ctx, calld->method);
   }
   reset_auth_metadata_context(&calld->auth_md_context);
 }
@@ -337,7 +340,7 @@ static void destroy_channel_elem(grpc_exec_ctx *exec_ctx,
   channel_data *chand = elem->channel_data;
   grpc_channel_security_connector *sc = chand->security_connector;
   if (sc != NULL) {
-    GRPC_SECURITY_CONNECTOR_UNREF(&sc->base, "client_auth_filter");
+    GRPC_SECURITY_CONNECTOR_UNREF(exec_ctx, &sc->base, "client_auth_filter");
   }
   GRPC_AUTH_CONTEXT_UNREF(chand->auth_context, "client_auth_filter");
 }
diff --git a/src/core/lib/security/transport/secure_endpoint.c b/src/core/lib/security/transport/secure_endpoint.c
index 750c3675b1..18a7a6f7e7 100644
--- a/src/core/lib/security/transport/secure_endpoint.c
+++ b/src/core/lib/security/transport/secure_endpoint.c
@@ -46,6 +46,7 @@
 #include "src/core/lib/profiling/timers.h"
 #include "src/core/lib/security/transport/secure_endpoint.h"
 #include "src/core/lib/security/transport/tsi_error.h"
+#include "src/core/lib/slice/slice_internal.h"
 #include "src/core/lib/slice/slice_string_helpers.h"
 #include "src/core/lib/support/string.h"
 #include "src/core/lib/tsi/transport_security_interface.h"
@@ -80,11 +81,11 @@ static void destroy(grpc_exec_ctx *exec_ctx, secure_endpoint *secure_ep) {
   secure_endpoint *ep = secure_ep;
   grpc_endpoint_destroy(exec_ctx, ep->wrapped_ep);
   tsi_frame_protector_destroy(ep->protector);
-  grpc_slice_buffer_destroy(&ep->leftover_bytes);
-  grpc_slice_unref(ep->read_staging_buffer);
-  grpc_slice_unref(ep->write_staging_buffer);
-  grpc_slice_buffer_destroy(&ep->output_buffer);
-  grpc_slice_buffer_destroy(&ep->source_buffer);
+  grpc_slice_buffer_destroy_internal(exec_ctx, &ep->leftover_bytes);
+  grpc_slice_unref_internal(exec_ctx, ep->read_staging_buffer);
+  grpc_slice_unref_internal(exec_ctx, ep->write_staging_buffer);
+  grpc_slice_buffer_destroy_internal(exec_ctx, &ep->output_buffer);
+  grpc_slice_buffer_destroy_internal(exec_ctx, &ep->source_buffer);
   gpr_mu_destroy(&ep->protector_mu);
   gpr_free(ep);
 }
@@ -160,7 +161,7 @@ static void on_read(grpc_exec_ctx *exec_ctx, void *user_data,
   uint8_t *end = GRPC_SLICE_END_PTR(ep->read_staging_buffer);
 
   if (error != GRPC_ERROR_NONE) {
-    grpc_slice_buffer_reset_and_unref(ep->read_buffer);
+    grpc_slice_buffer_reset_and_unref_internal(exec_ctx, ep->read_buffer);
     call_read_cb(exec_ctx, ep, GRPC_ERROR_CREATE_REFERENCING(
                                    "Secure read failed", &error, 1));
     return;
@@ -215,10 +216,10 @@ static void on_read(grpc_exec_ctx *exec_ctx, void *user_data,
 
   /* TODO(yangg) experiment with moving this block after read_cb to see if it
      helps latency */
-  grpc_slice_buffer_reset_and_unref(&ep->source_buffer);
+  grpc_slice_buffer_reset_and_unref_internal(exec_ctx, &ep->source_buffer);
 
   if (result != TSI_OK) {
-    grpc_slice_buffer_reset_and_unref(ep->read_buffer);
+    grpc_slice_buffer_reset_and_unref_internal(exec_ctx, ep->read_buffer);
     call_read_cb(exec_ctx, ep, grpc_set_tsi_error_result(
                                    GRPC_ERROR_CREATE("Unwrap failed"), result));
     return;
@@ -232,7 +233,7 @@ static void endpoint_read(grpc_exec_ctx *exec_ctx, grpc_endpoint *secure_ep,
   secure_endpoint *ep = (secure_endpoint *)secure_ep;
   ep->read_cb = cb;
   ep->read_buffer = slices;
-  grpc_slice_buffer_reset_and_unref(ep->read_buffer);
+  grpc_slice_buffer_reset_and_unref_internal(exec_ctx, ep->read_buffer);
 
   SECURE_ENDPOINT_REF(ep, "read");
   if (ep->leftover_bytes.count) {
@@ -264,7 +265,7 @@ static void endpoint_write(grpc_exec_ctx *exec_ctx, grpc_endpoint *secure_ep,
   uint8_t *cur = GRPC_SLICE_START_PTR(ep->write_staging_buffer);
   uint8_t *end = GRPC_SLICE_END_PTR(ep->write_staging_buffer);
 
-  grpc_slice_buffer_reset_and_unref(&ep->output_buffer);
+  grpc_slice_buffer_reset_and_unref_internal(exec_ctx, &ep->output_buffer);
 
   if (grpc_trace_secure_endpoint) {
     for (i = 0; i < slices->count; i++) {
@@ -328,7 +329,7 @@ static void endpoint_write(grpc_exec_ctx *exec_ctx, grpc_endpoint *secure_ep,
 
   if (result != TSI_OK) {
     /* TODO(yangg) do different things according to the error type? */
-    grpc_slice_buffer_reset_and_unref(&ep->output_buffer);
+    grpc_slice_buffer_reset_and_unref_internal(exec_ctx, &ep->output_buffer);
     grpc_closure_sched(
         exec_ctx, cb,
         grpc_set_tsi_error_result(GRPC_ERROR_CREATE("Wrap failed"), result));
@@ -409,7 +410,7 @@ grpc_endpoint *grpc_secure_endpoint_create(
   grpc_slice_buffer_init(&ep->leftover_bytes);
   for (i = 0; i < leftover_nslices; i++) {
     grpc_slice_buffer_add(&ep->leftover_bytes,
-                          grpc_slice_ref(leftover_slices[i]));
+                          grpc_slice_ref_internal(leftover_slices[i]));
   }
   ep->write_staging_buffer = grpc_slice_malloc(STAGING_BUFFER_SIZE);
   ep->read_staging_buffer = grpc_slice_malloc(STAGING_BUFFER_SIZE);
diff --git a/src/core/lib/security/transport/security_connector.c b/src/core/lib/security/transport/security_connector.c
index 17ad681c82..5aa26e0577 100644
--- a/src/core/lib/security/transport/security_connector.c
+++ b/src/core/lib/security/transport/security_connector.c
@@ -172,7 +172,8 @@ grpc_security_connector *grpc_security_connector_ref(
 }
 
 #ifdef GRPC_SECURITY_CONNECTOR_REFCOUNT_DEBUG
-void grpc_security_connector_unref(grpc_security_connector *sc,
+void grpc_security_connector_unref(grpc_exec_ctx *exec_ctx,
+                                   grpc_security_connector *sc,
                                    const char *file, int line,
                                    const char *reason) {
   if (sc == NULL) return;
@@ -180,14 +181,15 @@ void grpc_security_connector_unref(grpc_security_connector *sc,
           "SECURITY_CONNECTOR:%p unref %d -> %d %s", sc,
           (int)sc->refcount.count, (int)sc->refcount.count - 1, reason);
 #else
-void grpc_security_connector_unref(grpc_security_connector *sc) {
+void grpc_security_connector_unref(grpc_exec_ctx *exec_ctx,
+                                   grpc_security_connector *sc) {
   if (sc == NULL) return;
 #endif
-  if (gpr_unref(&sc->refcount)) sc->vtable->destroy(sc);
+  if (gpr_unref(&sc->refcount)) sc->vtable->destroy(exec_ctx, sc);
 }
 
-static void connector_pointer_arg_destroy(void *p) {
-  GRPC_SECURITY_CONNECTOR_UNREF(p, "connector_pointer_arg_destroy");
+static void connector_pointer_arg_destroy(grpc_exec_ctx *exec_ctx, void *p) {
+  GRPC_SECURITY_CONNECTOR_UNREF(exec_ctx, p, "connector_pointer_arg_destroy");
 }
 
 static void *connector_pointer_arg_copy(void *p) {
@@ -233,13 +235,17 @@ grpc_security_connector *grpc_find_security_connector_in_args(
 
 /* -- Fake implementation. -- */
 
-static void fake_channel_destroy(grpc_security_connector *sc) {
+static void fake_channel_destroy(grpc_exec_ctx *exec_ctx,
+                                 grpc_security_connector *sc) {
   grpc_channel_security_connector *c = (grpc_channel_security_connector *)sc;
-  grpc_call_credentials_unref(c->request_metadata_creds);
+  grpc_call_credentials_unref(exec_ctx, c->request_metadata_creds);
   gpr_free(sc);
 }
 
-static void fake_server_destroy(grpc_security_connector *sc) { gpr_free(sc); }
+static void fake_server_destroy(grpc_exec_ctx *exec_ctx,
+                                grpc_security_connector *sc) {
+  gpr_free(sc);
+}
 
 static void fake_check_peer(grpc_exec_ctx *exec_ctx,
                             grpc_security_connector *sc, tsi_peer peer,
@@ -351,10 +357,11 @@ typedef struct {
   tsi_ssl_handshaker_factory *handshaker_factory;
 } grpc_ssl_server_security_connector;
 
-static void ssl_channel_destroy(grpc_security_connector *sc) {
+static void ssl_channel_destroy(grpc_exec_ctx *exec_ctx,
+                                grpc_security_connector *sc) {
   grpc_ssl_channel_security_connector *c =
       (grpc_ssl_channel_security_connector *)sc;
-  grpc_call_credentials_unref(c->base.request_metadata_creds);
+  grpc_call_credentials_unref(exec_ctx, c->base.request_metadata_creds);
   if (c->handshaker_factory != NULL) {
     tsi_ssl_handshaker_factory_destroy(c->handshaker_factory);
   }
@@ -363,7 +370,8 @@ static void ssl_channel_destroy(grpc_security_connector *sc) {
   gpr_free(sc);
 }
 
-static void ssl_server_destroy(grpc_security_connector *sc) {
+static void ssl_server_destroy(grpc_exec_ctx *exec_ctx,
+                               grpc_security_connector *sc) {
   grpc_ssl_server_security_connector *c =
       (grpc_ssl_server_security_connector *)sc;
   if (c->handshaker_factory != NULL) {
@@ -669,7 +677,7 @@ size_t grpc_get_default_ssl_roots(const unsigned char **pem_root_certs) {
 }
 
 grpc_security_status grpc_ssl_channel_security_connector_create(
-    grpc_call_credentials *request_metadata_creds,
+    grpc_exec_ctx *exec_ctx, grpc_call_credentials *request_metadata_creds,
     const grpc_ssl_config *config, const char *target_name,
     const char *overridden_target_name, grpc_channel_security_connector **sc) {
   size_t num_alpn_protocols = grpc_chttp2_num_alpn_versions();
@@ -730,7 +738,7 @@ grpc_security_status grpc_ssl_channel_security_connector_create(
   if (result != TSI_OK) {
     gpr_log(GPR_ERROR, "Handshaker factory creation failed with %s.",
             tsi_result_to_string(result));
-    ssl_channel_destroy(&c->base.base);
+    ssl_channel_destroy(exec_ctx, &c->base.base);
     *sc = NULL;
     goto error;
   }
@@ -746,7 +754,8 @@ error:
 }
 
 grpc_security_status grpc_ssl_server_security_connector_create(
-    const grpc_ssl_server_config *config, grpc_server_security_connector **sc) {
+    grpc_exec_ctx *exec_ctx, const grpc_ssl_server_config *config,
+    grpc_server_security_connector **sc) {
   size_t num_alpn_protocols = grpc_chttp2_num_alpn_versions();
   const unsigned char **alpn_protocol_strings =
       gpr_malloc(sizeof(const char *) * num_alpn_protocols);
@@ -786,7 +795,7 @@ grpc_security_status grpc_ssl_server_security_connector_create(
   if (result != TSI_OK) {
     gpr_log(GPR_ERROR, "Handshaker factory creation failed with %s.",
             tsi_result_to_string(result));
-    ssl_server_destroy(&c->base.base);
+    ssl_server_destroy(exec_ctx, &c->base.base);
     *sc = NULL;
     goto error;
   }
diff --git a/src/core/lib/security/transport/security_connector.h b/src/core/lib/security/transport/security_connector.h
index a84b359051..eba4e6d1d7 100644
--- a/src/core/lib/security/transport/security_connector.h
+++ b/src/core/lib/security/transport/security_connector.h
@@ -60,7 +60,7 @@ typedef struct grpc_security_connector grpc_security_connector;
 #define GRPC_SECURITY_CONNECTOR_ARG "grpc.security_connector"
 
 typedef struct {
-  void (*destroy)(grpc_security_connector *sc);
+  void (*destroy)(grpc_exec_ctx *exec_ctx, grpc_security_connector *sc);
   void (*check_peer)(grpc_exec_ctx *exec_ctx, grpc_security_connector *sc,
                      tsi_peer peer, grpc_auth_context **auth_context,
                      grpc_closure *on_peer_checked);
@@ -81,20 +81,23 @@ struct grpc_security_connector {
 #ifdef GRPC_SECURITY_CONNECTOR_REFCOUNT_DEBUG
 #define GRPC_SECURITY_CONNECTOR_REF(p, r) \
   grpc_security_connector_ref((p), __FILE__, __LINE__, (r))
-#define GRPC_SECURITY_CONNECTOR_UNREF(p, r) \
-  grpc_security_connector_unref((p), __FILE__, __LINE__, (r))
+#define GRPC_SECURITY_CONNECTOR_UNREF(exec_ctx, p, r) \
+  grpc_security_connector_unref((exec_ctx), (p), __FILE__, __LINE__, (r))
 grpc_security_connector *grpc_security_connector_ref(
     grpc_security_connector *policy, const char *file, int line,
     const char *reason);
-void grpc_security_connector_unref(grpc_security_connector *policy,
+void grpc_security_connector_unref(grpc_exec_ctx *exec_ctx,
+                                   grpc_security_connector *policy,
                                    const char *file, int line,
                                    const char *reason);
 #else
 #define GRPC_SECURITY_CONNECTOR_REF(p, r) grpc_security_connector_ref((p))
-#define GRPC_SECURITY_CONNECTOR_UNREF(p, r) grpc_security_connector_unref((p))
+#define GRPC_SECURITY_CONNECTOR_UNREF(exec_ctx, p, r) \
+  grpc_security_connector_unref((exec_ctx), (p))
 grpc_security_connector *grpc_security_connector_ref(
     grpc_security_connector *policy);
-void grpc_security_connector_unref(grpc_security_connector *policy);
+void grpc_security_connector_unref(grpc_exec_ctx *exec_ctx,
+                                   grpc_security_connector *policy);
 #endif
 
 /* Check the peer. Callee takes ownership of the peer object.
@@ -203,7 +206,7 @@ typedef struct {
   specific error code otherwise.
 */
 grpc_security_status grpc_ssl_channel_security_connector_create(
-    grpc_call_credentials *request_metadata_creds,
+    grpc_exec_ctx *exec_ctx, grpc_call_credentials *request_metadata_creds,
     const grpc_ssl_config *config, const char *target_name,
     const char *overridden_target_name, grpc_channel_security_connector **sc);
 
@@ -232,7 +235,8 @@ typedef struct {
   specific error code otherwise.
 */
 grpc_security_status grpc_ssl_server_security_connector_create(
-    const grpc_ssl_server_config *config, grpc_server_security_connector **sc);
+    grpc_exec_ctx *exec_ctx, const grpc_ssl_server_config *config,
+    grpc_server_security_connector **sc);
 
 /* Util. */
 const tsi_peer_property *tsi_peer_get_property_by_name(const tsi_peer *peer,
diff --git a/src/core/lib/security/transport/security_handshaker.c b/src/core/lib/security/transport/security_handshaker.c
index 748bf4a432..5e75856c7a 100644
--- a/src/core/lib/security/transport/security_handshaker.c
+++ b/src/core/lib/security/transport/security_handshaker.c
@@ -42,9 +42,11 @@
 
 #include "src/core/lib/channel/channel_args.h"
 #include "src/core/lib/channel/handshaker.h"
+#include "src/core/lib/channel/handshaker_registry.h"
 #include "src/core/lib/security/context/security_context.h"
 #include "src/core/lib/security/transport/secure_endpoint.h"
 #include "src/core/lib/security/transport/tsi_error.h"
+#include "src/core/lib/slice/slice_internal.h"
 
 #define GRPC_INITIAL_HANDSHAKE_BUFFER_SIZE 256
 
@@ -86,26 +88,27 @@ static void security_handshaker_unref(grpc_exec_ctx *exec_ctx,
       grpc_endpoint_destroy(exec_ctx, h->endpoint_to_destroy);
     }
     if (h->read_buffer_to_destroy != NULL) {
-      grpc_slice_buffer_destroy(h->read_buffer_to_destroy);
+      grpc_slice_buffer_destroy_internal(exec_ctx, h->read_buffer_to_destroy);
       gpr_free(h->read_buffer_to_destroy);
     }
     gpr_free(h->handshake_buffer);
-    grpc_slice_buffer_destroy(&h->left_overs);
-    grpc_slice_buffer_destroy(&h->outgoing);
+    grpc_slice_buffer_destroy_internal(exec_ctx, &h->left_overs);
+    grpc_slice_buffer_destroy_internal(exec_ctx, &h->outgoing);
     GRPC_AUTH_CONTEXT_UNREF(h->auth_context, "handshake");
-    GRPC_SECURITY_CONNECTOR_UNREF(h->connector, "handshake");
+    GRPC_SECURITY_CONNECTOR_UNREF(exec_ctx, h->connector, "handshake");
     gpr_free(h);
   }
 }
 
 // Set args fields to NULL, saving the endpoint and read buffer for
 // later destruction.
-static void cleanup_args_for_failure_locked(security_handshaker *h) {
+static void cleanup_args_for_failure_locked(grpc_exec_ctx *exec_ctx,
+                                            security_handshaker *h) {
   h->endpoint_to_destroy = h->args->endpoint;
   h->args->endpoint = NULL;
   h->read_buffer_to_destroy = h->args->read_buffer;
   h->args->read_buffer = NULL;
-  grpc_channel_args_destroy(h->args->args);
+  grpc_channel_args_destroy(exec_ctx, h->args->args);
   h->args->args = NULL;
 }
 
@@ -130,7 +133,7 @@ static void security_handshake_failed_locked(grpc_exec_ctx *exec_ctx,
     grpc_endpoint_shutdown(exec_ctx, h->args->endpoint);
     // Not shutting down, so the write failed.  Clean up before
     // invoking the callback.
-    cleanup_args_for_failure_locked(h);
+    cleanup_args_for_failure_locked(exec_ctx, h);
     // Set shutdown to true so that subsequent calls to
     // security_handshaker_shutdown() do nothing.
     h->shutdown = true;
@@ -165,13 +168,13 @@ static void on_peer_checked(grpc_exec_ctx *exec_ctx, void *arg,
   h->left_overs.length = 0;
   // Clear out the read buffer before it gets passed to the transport,
   // since any excess bytes were already copied to h->left_overs.
-  grpc_slice_buffer_reset_and_unref(h->args->read_buffer);
+  grpc_slice_buffer_reset_and_unref_internal(exec_ctx, h->args->read_buffer);
   // Add auth context to channel args.
   grpc_arg auth_context_arg = grpc_auth_context_to_arg(h->auth_context);
   grpc_channel_args *tmp_args = h->args->args;
   h->args->args =
       grpc_channel_args_copy_and_add(tmp_args, &auth_context_arg, 1);
-  grpc_channel_args_destroy(tmp_args);
+  grpc_channel_args_destroy(exec_ctx, tmp_args);
   // Invoke callback.
   grpc_closure_sched(exec_ctx, h->on_handshake_done, GRPC_ERROR_NONE);
   // Set shutdown to true so that subsequent calls to
@@ -218,7 +221,7 @@ static grpc_error *send_handshake_bytes_to_peer_locked(grpc_exec_ctx *exec_ctx,
   // Send data.
   grpc_slice to_send =
       grpc_slice_from_copied_buffer((const char *)h->handshake_buffer, offset);
-  grpc_slice_buffer_reset_and_unref(&h->outgoing);
+  grpc_slice_buffer_reset_and_unref_internal(exec_ctx, &h->outgoing);
   grpc_slice_buffer_add(&h->outgoing, to_send);
   grpc_endpoint_write(exec_ctx, h->args->endpoint, &h->outgoing,
                       &h->on_handshake_data_sent_to_peer);
@@ -287,7 +290,7 @@ static void on_handshake_data_received_from_peer(grpc_exec_ctx *exec_ctx,
           grpc_slice_split_tail(&h->args->read_buffer->slices[i],
                                 consumed_slice_size));
       /* split_tail above increments refcount. */
-      grpc_slice_unref(h->args->read_buffer->slices[i]);
+      grpc_slice_unref_internal(exec_ctx, h->args->read_buffer->slices[i]);
     }
     grpc_slice_buffer_addn(
         &h->left_overs, &h->args->read_buffer->slices[i + 1],
@@ -350,7 +353,7 @@ static void security_handshaker_shutdown(grpc_exec_ctx *exec_ctx,
   if (!h->shutdown) {
     h->shutdown = true;
     grpc_endpoint_shutdown(exec_ctx, h->args->endpoint);
-    cleanup_args_for_failure_locked(h);
+    cleanup_args_for_failure_locked(exec_ctx, h);
   }
   gpr_mu_unlock(&h->mu);
 }
@@ -436,6 +439,45 @@ static grpc_handshaker *fail_handshaker_create() {
 }
 
 //
+// handshaker factories
+//
+
+static void client_handshaker_factory_add_handshakers(
+    grpc_exec_ctx *exec_ctx, grpc_handshaker_factory *handshaker_factory,
+    const grpc_channel_args *args, grpc_handshake_manager *handshake_mgr) {
+  grpc_channel_security_connector *security_connector =
+      (grpc_channel_security_connector *)grpc_find_security_connector_in_args(
+          args);
+  grpc_channel_security_connector_add_handshakers(exec_ctx, security_connector,
+                                                  handshake_mgr);
+}
+
+static void server_handshaker_factory_add_handshakers(
+    grpc_exec_ctx *exec_ctx, grpc_handshaker_factory *hf,
+    const grpc_channel_args *args, grpc_handshake_manager *handshake_mgr) {
+  grpc_server_security_connector *security_connector =
+      (grpc_server_security_connector *)grpc_find_security_connector_in_args(
+          args);
+  grpc_server_security_connector_add_handshakers(exec_ctx, security_connector,
+                                                 handshake_mgr);
+}
+
+static void handshaker_factory_destroy(
+    grpc_exec_ctx *exec_ctx, grpc_handshaker_factory *handshaker_factory) {}
+
+static const grpc_handshaker_factory_vtable client_handshaker_factory_vtable = {
+    client_handshaker_factory_add_handshakers, handshaker_factory_destroy};
+
+static grpc_handshaker_factory client_handshaker_factory = {
+    &client_handshaker_factory_vtable};
+
+static const grpc_handshaker_factory_vtable server_handshaker_factory_vtable = {
+    server_handshaker_factory_add_handshakers, handshaker_factory_destroy};
+
+static grpc_handshaker_factory server_handshaker_factory = {
+    &server_handshaker_factory_vtable};
+
+//
 // exported functions
 //
 
@@ -450,3 +492,10 @@ grpc_handshaker *grpc_security_handshaker_create(
     return security_handshaker_create(exec_ctx, handshaker, connector);
   }
 }
+
+void grpc_security_register_handshaker_factories() {
+  grpc_handshaker_factory_register(false /* at_start */, HANDSHAKER_CLIENT,
+                                   &client_handshaker_factory);
+  grpc_handshaker_factory_register(false /* at_start */, HANDSHAKER_SERVER,
+                                   &server_handshaker_factory);
+}
diff --git a/src/core/lib/security/transport/security_handshaker.h b/src/core/lib/security/transport/security_handshaker.h
index 5ddbf4b451..0b9eda178f 100644
--- a/src/core/lib/security/transport/security_handshaker.h
+++ b/src/core/lib/security/transport/security_handshaker.h
@@ -43,4 +43,7 @@ grpc_handshaker *grpc_security_handshaker_create(
     grpc_exec_ctx *exec_ctx, tsi_handshaker *handshaker,
     grpc_security_connector *connector);
 
+/// Registers security handshaker factories.
+void grpc_security_register_handshaker_factories();
+
 #endif /* GRPC_CORE_LIB_SECURITY_TRANSPORT_SECURITY_HANDSHAKER_H */
diff --git a/src/core/lib/security/transport/server_auth_filter.c b/src/core/lib/security/transport/server_auth_filter.c
index 5b4adc4661..5e98ba895d 100644
--- a/src/core/lib/security/transport/server_auth_filter.c
+++ b/src/core/lib/security/transport/server_auth_filter.c
@@ -83,7 +83,8 @@ static grpc_metadata_array metadata_batch_to_md_array(
   return result;
 }
 
-static grpc_mdelem *remove_consumed_md(void *user_data, grpc_mdelem *md) {
+static grpc_mdelem *remove_consumed_md(grpc_exec_ctx *exec_ctx, void *user_data,
+                                       grpc_mdelem *md) {
   grpc_call_element *elem = user_data;
   call_data *calld = elem->call_data;
   size_t i;
@@ -129,8 +130,8 @@ static void on_md_processing_done(
   if (status == GRPC_STATUS_OK) {
     calld->consumed_md = consumed_md;
     calld->num_consumed_md = num_consumed_md;
-    grpc_metadata_batch_filter(calld->recv_initial_metadata, remove_consumed_md,
-                               elem);
+    grpc_metadata_batch_filter(&exec_ctx, calld->recv_initial_metadata,
+                               remove_consumed_md, elem);
     grpc_metadata_array_destroy(&calld->md);
     grpc_closure_sched(&exec_ctx, calld->on_done_recv, GRPC_ERROR_NONE);
   } else {
@@ -150,7 +151,7 @@ static void on_md_processing_done(
     calld->transport_op->send_trailing_metadata = NULL;
     close_op->on_complete =
         grpc_closure_create(destroy_op, close_op, grpc_schedule_on_exec_ctx);
-    grpc_transport_stream_op_add_close(close_op, status, &message);
+    grpc_transport_stream_op_add_close(&exec_ctx, close_op, status, &message);
     grpc_call_next_op(&exec_ctx, elem, close_op);
     grpc_closure_sched(&exec_ctx, calld->on_done_recv,
                        grpc_error_set_int(GRPC_ERROR_CREATE(error_details),
@@ -265,7 +266,7 @@ static void destroy_channel_elem(grpc_exec_ctx *exec_ctx,
   /* grab pointers to our data from the channel element */
   channel_data *chand = elem->channel_data;
   GRPC_AUTH_CONTEXT_UNREF(chand->auth_context, "server_auth_filter");
-  grpc_server_credentials_unref(chand->creds);
+  grpc_server_credentials_unref(exec_ctx, chand->creds);
 }
 
 const grpc_channel_filter grpc_server_auth_filter = {
diff --git a/src/core/lib/security/util/b64.c b/src/core/lib/security/util/b64.c
index 4892e8e621..bbd7e335a6 100644
--- a/src/core/lib/security/util/b64.c
+++ b/src/core/lib/security/util/b64.c
@@ -40,6 +40,8 @@
 #include <grpc/support/log.h>
 #include <grpc/support/useful.h>
 
+#include "src/core/lib/slice/slice_internal.h"
+
 /* --- Constants. --- */
 
 static const int8_t base64_bytes[] = {
@@ -120,8 +122,9 @@ char *grpc_base64_encode(const void *vdata, size_t data_size, int url_safe,
   return result;
 }
 
-grpc_slice grpc_base64_decode(const char *b64, int url_safe) {
-  return grpc_base64_decode_with_len(b64, strlen(b64), url_safe);
+grpc_slice grpc_base64_decode(grpc_exec_ctx *exec_ctx, const char *b64,
+                              int url_safe) {
+  return grpc_base64_decode_with_len(exec_ctx, b64, strlen(b64), url_safe);
 }
 
 static void decode_one_char(const unsigned char *codes, unsigned char *result,
@@ -182,8 +185,8 @@ static int decode_group(const unsigned char *codes, size_t num_codes,
   return 1;
 }
 
-grpc_slice grpc_base64_decode_with_len(const char *b64, size_t b64_len,
-                                       int url_safe) {
+grpc_slice grpc_base64_decode_with_len(grpc_exec_ctx *exec_ctx, const char *b64,
+                                       size_t b64_len, int url_safe) {
   grpc_slice result = grpc_slice_malloc(b64_len);
   unsigned char *current = GRPC_SLICE_START_PTR(result);
   size_t result_size = 0;
@@ -228,6 +231,6 @@ grpc_slice grpc_base64_decode_with_len(const char *b64, size_t b64_len,
   return result;
 
 fail:
-  grpc_slice_unref(result);
+  grpc_slice_unref_internal(exec_ctx, result);
   return gpr_empty_slice();
 }
diff --git a/src/core/lib/security/util/b64.h b/src/core/lib/security/util/b64.h
index 6ea0b5365b..d42a136f61 100644
--- a/src/core/lib/security/util/b64.h
+++ b/src/core/lib/security/util/b64.h
@@ -43,10 +43,11 @@ char *grpc_base64_encode(const void *data, size_t data_size, int url_safe,
 
 /* Decodes data according to the base64 specification. Returns an empty
    slice in case of failure. */
-grpc_slice grpc_base64_decode(const char *b64, int url_safe);
+grpc_slice grpc_base64_decode(grpc_exec_ctx *exec_ctx, const char *b64,
+                              int url_safe);
 
 /* Same as above except that the length is provided by the caller. */
-grpc_slice grpc_base64_decode_with_len(const char *b64, size_t b64_len,
-                                       int url_safe);
+grpc_slice grpc_base64_decode_with_len(grpc_exec_ctx *exec_ctx, const char *b64,
+                                       size_t b64_len, int url_safe);
 
 #endif /* GRPC_CORE_LIB_SECURITY_UTIL_B64_H */
diff --git a/src/core/lib/slice/percent_encoding.c b/src/core/lib/slice/percent_encoding.c
index b9e35f1c71..c76c58d371 100644
--- a/src/core/lib/slice/percent_encoding.c
+++ b/src/core/lib/slice/percent_encoding.c
@@ -35,6 +35,8 @@
 
 #include <grpc/support/log.h>
 
+#include "src/core/lib/slice/slice_internal.h"
+
 const uint8_t grpc_url_percent_encoding_unreserved_bytes[256 / 8] = {
     0x00, 0x00, 0x00, 0x00, 0x00, 0x60, 0xff, 0x03, 0xfe, 0xff, 0xff,
     0x87, 0xfe, 0xff, 0xff, 0x47, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
@@ -66,7 +68,7 @@ grpc_slice grpc_percent_encode_slice(grpc_slice slice,
   }
   // no unreserved bytes: return the string unmodified
   if (!any_reserved_bytes) {
-    return grpc_slice_ref(slice);
+    return grpc_slice_ref_internal(slice);
   }
   // second pass: actually encode
   grpc_slice out = grpc_slice_malloc(output_length);
@@ -119,7 +121,7 @@ bool grpc_strict_percent_decode_slice(grpc_slice slice_in,
     }
   }
   if (!any_percent_encoded_stuff) {
-    *slice_out = grpc_slice_ref(slice_in);
+    *slice_out = grpc_slice_ref_internal(slice_in);
     return true;
   }
   p = GRPC_SLICE_START_PTR(slice_in);
@@ -158,7 +160,7 @@ grpc_slice grpc_permissive_percent_decode_slice(grpc_slice slice_in) {
     }
   }
   if (!any_percent_encoded_stuff) {
-    return grpc_slice_ref(slice_in);
+    return grpc_slice_ref_internal(slice_in);
   }
   p = GRPC_SLICE_START_PTR(slice_in);
   grpc_slice out = grpc_slice_malloc(out_length);
diff --git a/src/core/lib/slice/slice.c b/src/core/lib/slice/slice.c
index 52977e6d9a..76118102ec 100644
--- a/src/core/lib/slice/slice.c
+++ b/src/core/lib/slice/slice.c
@@ -31,12 +31,16 @@
  *
  */
 
+#include "src/core/lib/slice/slice_internal.h"
+
 #include <grpc/slice.h>
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
 
 #include <string.h>
 
+#include "src/core/lib/iomgr/exec_ctx.h"
+
 grpc_slice gpr_empty_slice(void) {
   grpc_slice out;
   out.refcount = 0;
@@ -44,25 +48,37 @@ grpc_slice gpr_empty_slice(void) {
   return out;
 }
 
-grpc_slice grpc_slice_ref(grpc_slice slice) {
+grpc_slice grpc_slice_ref_internal(grpc_slice slice) {
   if (slice.refcount) {
     slice.refcount->ref(slice.refcount);
   }
   return slice;
 }
 
-void grpc_slice_unref(grpc_slice slice) {
+void grpc_slice_unref_internal(grpc_exec_ctx *exec_ctx, grpc_slice slice) {
   if (slice.refcount) {
-    slice.refcount->unref(slice.refcount);
+    slice.refcount->unref(exec_ctx, slice.refcount);
   }
 }
 
+/* Public API */
+grpc_slice grpc_slice_ref(grpc_slice slice) {
+  return grpc_slice_ref_internal(slice);
+}
+
+/* Public API */
+void grpc_slice_unref(grpc_slice slice) {
+  grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
+  grpc_slice_unref_internal(&exec_ctx, slice);
+  grpc_exec_ctx_finish(&exec_ctx);
+}
+
 /* grpc_slice_from_static_string support structure - a refcount that does
    nothing */
-static void noop_ref_or_unref(void *unused) {}
+static void noop_ref(void *unused) {}
+static void noop_unref(grpc_exec_ctx *exec_ctx, void *unused) {}
 
-static grpc_slice_refcount noop_refcount = {noop_ref_or_unref,
-                                            noop_ref_or_unref};
+static grpc_slice_refcount noop_refcount = {noop_ref, noop_unref};
 
 grpc_slice grpc_slice_from_static_string(const char *s) {
   grpc_slice slice;
@@ -86,7 +102,7 @@ static void new_slice_ref(void *p) {
   gpr_ref(&r->refs);
 }
 
-static void new_slice_unref(void *p) {
+static void new_slice_unref(grpc_exec_ctx *exec_ctx, void *p) {
   new_slice_refcount *r = p;
   if (gpr_unref(&r->refs)) {
     r->user_destroy(r->user_data);
@@ -131,7 +147,7 @@ static void new_with_len_ref(void *p) {
   gpr_ref(&r->refs);
 }
 
-static void new_with_len_unref(void *p) {
+static void new_with_len_unref(grpc_exec_ctx *exec_ctx, void *p) {
   new_with_len_slice_refcount *r = p;
   if (gpr_unref(&r->refs)) {
     r->user_destroy(r->user_data, r->user_length);
@@ -177,7 +193,7 @@ static void malloc_ref(void *p) {
   gpr_ref(&r->refs);
 }
 
-static void malloc_unref(void *p) {
+static void malloc_unref(grpc_exec_ctx *exec_ctx, void *p) {
   malloc_refcount *r = p;
   if (gpr_unref(&r->refs)) {
     gpr_free(r);
diff --git a/src/core/lib/slice/slice_buffer.c b/src/core/lib/slice/slice_buffer.c
index 990ef128bd..08eaf4963a 100644
--- a/src/core/lib/slice/slice_buffer.c
+++ b/src/core/lib/slice/slice_buffer.c
@@ -40,6 +40,8 @@
 #include <grpc/support/log.h>
 #include <grpc/support/useful.h>
 
+#include "src/core/lib/slice/slice_internal.h"
+
 /* grow a buffer; requires GRPC_SLICE_BUFFER_INLINE_ELEMENTS > 1 */
 #define GROW(x) (3 * (x) / 2)
 
@@ -63,13 +65,20 @@ void grpc_slice_buffer_init(grpc_slice_buffer *sb) {
   sb->slices = sb->inlined;
 }
 
-void grpc_slice_buffer_destroy(grpc_slice_buffer *sb) {
-  grpc_slice_buffer_reset_and_unref(sb);
+void grpc_slice_buffer_destroy_internal(grpc_exec_ctx *exec_ctx,
+                                        grpc_slice_buffer *sb) {
+  grpc_slice_buffer_reset_and_unref_internal(exec_ctx, sb);
   if (sb->slices != sb->inlined) {
     gpr_free(sb->slices);
   }
 }
 
+void grpc_slice_buffer_destroy(grpc_slice_buffer *sb) {
+  grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
+  grpc_slice_buffer_destroy_internal(&exec_ctx, sb);
+  grpc_exec_ctx_finish(&exec_ctx);
+}
+
 uint8_t *grpc_slice_buffer_tiny_add(grpc_slice_buffer *sb, size_t n) {
   grpc_slice *back;
   uint8_t *out;
@@ -154,17 +163,24 @@ void grpc_slice_buffer_pop(grpc_slice_buffer *sb) {
   }
 }
 
-void grpc_slice_buffer_reset_and_unref(grpc_slice_buffer *sb) {
+void grpc_slice_buffer_reset_and_unref_internal(grpc_exec_ctx *exec_ctx,
+                                                grpc_slice_buffer *sb) {
   size_t i;
 
   for (i = 0; i < sb->count; i++) {
-    grpc_slice_unref(sb->slices[i]);
+    grpc_slice_unref_internal(exec_ctx, sb->slices[i]);
   }
 
   sb->count = 0;
   sb->length = 0;
 }
 
+void grpc_slice_buffer_reset_and_unref(grpc_slice_buffer *sb) {
+  grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
+  grpc_slice_buffer_reset_and_unref_internal(&exec_ctx, sb);
+  grpc_exec_ctx_finish(&exec_ctx);
+}
+
 void grpc_slice_buffer_swap(grpc_slice_buffer *a, grpc_slice_buffer *b) {
   GPR_SWAP(size_t, a->count, b->count);
   GPR_SWAP(size_t, a->capacity, b->capacity);
diff --git a/src/core/lib/slice/slice_internal.h b/src/core/lib/slice/slice_internal.h
new file mode 100644
index 0000000000..6185333ca7
--- /dev/null
+++ b/src/core/lib/slice/slice_internal.h
@@ -0,0 +1,49 @@
+/*
+ *
+ * Copyright 2016, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#ifndef GRPC_CORE_LIB_SLICE_SLICE_INTERNAL_H
+#define GRPC_CORE_LIB_SLICE_SLICE_INTERNAL_H
+
+#include <grpc/slice.h>
+#include <grpc/slice_buffer.h>
+
+#include "src/core/lib/iomgr/exec_ctx.h"
+
+grpc_slice grpc_slice_ref_internal(grpc_slice slice);
+void grpc_slice_unref_internal(grpc_exec_ctx *exec_ctx, grpc_slice slice);
+void grpc_slice_buffer_reset_and_unref_internal(grpc_exec_ctx *exec_ctx,
+                                                grpc_slice_buffer *sb);
+void grpc_slice_buffer_destroy_internal(grpc_exec_ctx *exec_ctx,
+                                        grpc_slice_buffer *sb);
+
+#endif /* GRPC_CORE_LIB_SLICE_SLICE_INTERNAL_H */
diff --git a/src/core/lib/slice/slice_string_helpers.c b/src/core/lib/slice/slice_string_helpers.c
index 4731762ece..839c366b32 100644
--- a/src/core/lib/slice/slice_string_helpers.c
+++ b/src/core/lib/slice/slice_string_helpers.c
@@ -37,6 +37,7 @@
 
 #include <grpc/support/log.h>
 
+#include "src/core/lib/slice/slice_internal.h"
 #include "src/core/lib/support/string.h"
 
 char *grpc_dump_slice(grpc_slice s, uint32_t flags) {
@@ -84,6 +85,6 @@ void grpc_slice_split(grpc_slice str, const char *sep, grpc_slice_buffer *dst) {
     grpc_slice_buffer_add_indexed(
         dst, grpc_slice_sub(str, end + sep_len, GRPC_SLICE_LENGTH(str)));
   } else { /* no sep found, add whole input */
-    grpc_slice_buffer_add_indexed(dst, grpc_slice_ref(str));
+    grpc_slice_buffer_add_indexed(dst, grpc_slice_ref_internal(str));
   }
 }
diff --git a/src/core/lib/support/string.c b/src/core/lib/support/string.c
index f263f82baf..d20b86f7cf 100644
--- a/src/core/lib/support/string.c
+++ b/src/core/lib/support/string.c
@@ -276,10 +276,37 @@ int gpr_stricmp(const char *a, const char *b) {
   return ca - cb;
 }
 
+static void add_string_to_split(const char *beg, const char *end, char ***strs,
+                                size_t *nstrs, size_t *capstrs) {
+  char *out = gpr_malloc((size_t)(end - beg) + 1);
+  memcpy(out, beg, (size_t)(end - beg));
+  out[end - beg] = 0;
+  if (*nstrs == *capstrs) {
+    *capstrs = GPR_MAX(8, 2 * *capstrs);
+    *strs = gpr_realloc(*strs, sizeof(*strs) * *capstrs);
+  }
+  (*strs)[*nstrs] = out;
+  ++*nstrs;
+}
+
+void gpr_string_split(const char *input, const char *sep, char ***strs,
+                      size_t *nstrs) {
+  char *next;
+  *strs = NULL;
+  *nstrs = 0;
+  size_t capstrs = 0;
+  while ((next = strstr(input, sep))) {
+    add_string_to_split(input, next, strs, nstrs, &capstrs);
+    input = next + strlen(sep);
+  }
+  add_string_to_split(input, input + strlen(input), strs, nstrs, &capstrs);
+}
+
 void *gpr_memrchr(const void *s, int c, size_t n) {
   if (s == NULL) return NULL;
   char *b = (char *)s;
-  for (size_t i = 0; i < n; i++) {
+  size_t i;
+  for (i = 0; i < n; i++) {
     if (b[n - i - 1] == c) {
       return &b[n - i - 1];
     }
diff --git a/src/core/lib/support/string.h b/src/core/lib/support/string.h
index 6d1f7cc632..d1c52faed4 100644
--- a/src/core/lib/support/string.h
+++ b/src/core/lib/support/string.h
@@ -36,8 +36,6 @@
 
 #include <stddef.h>
 
-#include <grpc/slice.h>
-#include <grpc/slice_buffer.h>
 #include <grpc/support/port_platform.h>
 
 #ifdef __cplusplus
@@ -98,6 +96,9 @@ char *gpr_strjoin(const char **strs, size_t nstrs, size_t *total_length);
 char *gpr_strjoin_sep(const char **strs, size_t nstrs, const char *sep,
                       size_t *total_length);
 
+void gpr_string_split(const char *input, const char *sep, char ***strs,
+                      size_t *nstrs);
+
 /* A vector of strings... for building up a final string one piece at a time */
 typedef struct {
   char **strs;
diff --git a/src/core/lib/support/tmpfile.h b/src/core/lib/support/tmpfile.h
index 8952e5ec3d..f613cf9bc8 100644
--- a/src/core/lib/support/tmpfile.h
+++ b/src/core/lib/support/tmpfile.h
@@ -36,8 +36,6 @@
 
 #include <stdio.h>
 
-#include <grpc/slice.h>
-
 #ifdef __cplusplus
 extern "C" {
 #endif
diff --git a/src/core/lib/surface/README.md b/src/core/lib/surface/README.md
new file mode 100644
index 0000000000..74cbd71131
--- /dev/null
+++ b/src/core/lib/surface/README.md
@@ -0,0 +1,4 @@
+# Surface
+
+Surface provides the bulk of the gRPC Core public API, and translates it into
+calls against core components.
diff --git a/src/core/lib/surface/alarm.c b/src/core/lib/surface/alarm.c
index aa9d60ee6a..e71c0ebfc5 100644
--- a/src/core/lib/surface/alarm.c
+++ b/src/core/lib/surface/alarm.c
@@ -38,6 +38,7 @@
 
 struct grpc_alarm {
   grpc_timer alarm;
+  grpc_closure on_alarm;
   grpc_cq_completion completion;
   /** completion queue where events about this alarm will be posted */
   grpc_completion_queue *cq;
@@ -64,9 +65,11 @@ grpc_alarm *grpc_alarm_create(grpc_completion_queue *cq, gpr_timespec deadline,
   alarm->tag = tag;
 
   grpc_cq_begin_op(cq, tag);
+  grpc_closure_init(&alarm->on_alarm, alarm_cb, alarm,
+                    grpc_schedule_on_exec_ctx);
   grpc_timer_init(&exec_ctx, &alarm->alarm,
                   gpr_convert_clock_type(deadline, GPR_CLOCK_MONOTONIC),
-                  alarm_cb, alarm, gpr_now(GPR_CLOCK_MONOTONIC));
+                  &alarm->on_alarm, gpr_now(GPR_CLOCK_MONOTONIC));
   grpc_exec_ctx_finish(&exec_ctx);
   return alarm;
 }
diff --git a/src/core/lib/surface/byte_buffer.c b/src/core/lib/surface/byte_buffer.c
index d646591a65..c8e2fdfdad 100644
--- a/src/core/lib/surface/byte_buffer.c
+++ b/src/core/lib/surface/byte_buffer.c
@@ -35,6 +35,8 @@
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
 
+#include "src/core/lib/slice/slice_internal.h"
+
 grpc_byte_buffer *grpc_raw_byte_buffer_create(grpc_slice *slices,
                                               size_t nslices) {
   return grpc_raw_compressed_byte_buffer_create(slices, nslices,
@@ -50,7 +52,7 @@ grpc_byte_buffer *grpc_raw_compressed_byte_buffer_create(
   bb->data.raw.compression = compression;
   grpc_slice_buffer_init(&bb->data.raw.slice_buffer);
   for (i = 0; i < nslices; i++) {
-    grpc_slice_ref(slices[i]);
+    grpc_slice_ref_internal(slices[i]);
     grpc_slice_buffer_add(&bb->data.raw.slice_buffer, slices[i]);
   }
   return bb;
@@ -82,12 +84,14 @@ grpc_byte_buffer *grpc_byte_buffer_copy(grpc_byte_buffer *bb) {
 
 void grpc_byte_buffer_destroy(grpc_byte_buffer *bb) {
   if (!bb) return;
+  grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
   switch (bb->type) {
     case GRPC_BB_RAW:
-      grpc_slice_buffer_destroy(&bb->data.raw.slice_buffer);
+      grpc_slice_buffer_destroy_internal(&exec_ctx, &bb->data.raw.slice_buffer);
       break;
   }
   gpr_free(bb);
+  grpc_exec_ctx_finish(&exec_ctx);
 }
 
 size_t grpc_byte_buffer_length(grpc_byte_buffer *bb) {
diff --git a/src/core/lib/surface/byte_buffer_reader.c b/src/core/lib/surface/byte_buffer_reader.c
index 0089959fbb..1a6ccdaddb 100644
--- a/src/core/lib/surface/byte_buffer_reader.c
+++ b/src/core/lib/surface/byte_buffer_reader.c
@@ -42,6 +42,7 @@
 #include <grpc/support/log.h>
 
 #include "src/core/lib/compression/message_compress.h"
+#include "src/core/lib/slice/slice_internal.h"
 
 static int is_compressed(grpc_byte_buffer *buffer) {
   switch (buffer->type) {
@@ -56,13 +57,15 @@ static int is_compressed(grpc_byte_buffer *buffer) {
 
 int grpc_byte_buffer_reader_init(grpc_byte_buffer_reader *reader,
                                  grpc_byte_buffer *buffer) {
+  grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
   grpc_slice_buffer decompressed_slices_buffer;
   reader->buffer_in = buffer;
   switch (reader->buffer_in->type) {
     case GRPC_BB_RAW:
       grpc_slice_buffer_init(&decompressed_slices_buffer);
       if (is_compressed(reader->buffer_in)) {
-        if (grpc_msg_decompress(reader->buffer_in->data.raw.compression,
+        if (grpc_msg_decompress(&exec_ctx,
+                                reader->buffer_in->data.raw.compression,
                                 &reader->buffer_in->data.raw.slice_buffer,
                                 &decompressed_slices_buffer) == 0) {
           gpr_log(GPR_ERROR,
@@ -76,13 +79,15 @@ int grpc_byte_buffer_reader_init(grpc_byte_buffer_reader *reader,
               grpc_raw_byte_buffer_create(decompressed_slices_buffer.slices,
                                           decompressed_slices_buffer.count);
         }
-        grpc_slice_buffer_destroy(&decompressed_slices_buffer);
+        grpc_slice_buffer_destroy_internal(&exec_ctx,
+                                           &decompressed_slices_buffer);
       } else { /* not compressed, use the input buffer as output */
         reader->buffer_out = reader->buffer_in;
       }
       reader->current.index = 0;
       break;
   }
+  grpc_exec_ctx_finish(&exec_ctx);
   return 1;
 }
 
@@ -104,7 +109,8 @@ int grpc_byte_buffer_reader_next(grpc_byte_buffer_reader *reader,
       grpc_slice_buffer *slice_buffer;
       slice_buffer = &reader->buffer_out->data.raw.slice_buffer;
       if (reader->current.index < slice_buffer->count) {
-        *slice = grpc_slice_ref(slice_buffer->slices[reader->current.index]);
+        *slice = grpc_slice_ref_internal(
+            slice_buffer->slices[reader->current.index]);
         reader->current.index += 1;
         return 1;
       }
@@ -121,12 +127,14 @@ grpc_slice grpc_byte_buffer_reader_readall(grpc_byte_buffer_reader *reader) {
   grpc_slice out_slice = grpc_slice_malloc(input_size);
   uint8_t *const outbuf = GRPC_SLICE_START_PTR(out_slice); /* just an alias */
 
+  grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
   while (grpc_byte_buffer_reader_next(reader, &in_slice) != 0) {
     const size_t slice_length = GRPC_SLICE_LENGTH(in_slice);
     memcpy(&(outbuf[bytes_read]), GRPC_SLICE_START_PTR(in_slice), slice_length);
     bytes_read += slice_length;
-    grpc_slice_unref(in_slice);
+    grpc_slice_unref_internal(&exec_ctx, in_slice);
     GPR_ASSERT(bytes_read <= input_size);
   }
+  grpc_exec_ctx_finish(&exec_ctx);
   return out_slice;
 }
diff --git a/src/core/lib/surface/call.c b/src/core/lib/surface/call.c
index b20801005a..899e8fab3f 100644
--- a/src/core/lib/surface/call.c
+++ b/src/core/lib/surface/call.c
@@ -49,6 +49,7 @@
 #include "src/core/lib/compression/algorithm_metadata.h"
 #include "src/core/lib/iomgr/timer.h"
 #include "src/core/lib/profiling/timers.h"
+#include "src/core/lib/slice/slice_internal.h"
 #include "src/core/lib/slice/slice_string_helpers.h"
 #include "src/core/lib/support/string.h"
 #include "src/core/lib/surface/api_trace.h"
@@ -226,12 +227,12 @@ static void destroy_call(grpc_exec_ctx *exec_ctx, void *call_stack,
 static void receiving_slice_ready(grpc_exec_ctx *exec_ctx, void *bctlp,
                                   grpc_error *error);
 
-grpc_error *grpc_call_create(const grpc_call_create_args *args,
+grpc_error *grpc_call_create(grpc_exec_ctx *exec_ctx,
+                             const grpc_call_create_args *args,
                              grpc_call **out_call) {
   size_t i, j;
   grpc_channel_stack *channel_stack =
       grpc_channel_get_channel_stack(args->channel);
-  grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
   grpc_call *call;
   GPR_TIMER_BEGIN("grpc_call_create", 0);
   call = gpr_malloc(sizeof(grpc_call) + channel_stack->call_stack_size);
@@ -315,14 +316,14 @@ grpc_error *grpc_call_create(const grpc_call_create_args *args,
   GRPC_CHANNEL_INTERNAL_REF(args->channel, "call");
   /* initial refcount dropped by grpc_call_destroy */
   grpc_error *error = grpc_call_stack_init(
-      &exec_ctx, channel_stack, 1, destroy_call, call, call->context,
+      exec_ctx, channel_stack, 1, destroy_call, call, call->context,
       args->server_transport_data, path, call->start_time, send_deadline,
       CALL_STACK_FROM_CALL(call));
   if (error != GRPC_ERROR_NONE) {
     grpc_status_code status;
     const char *error_str;
     grpc_error_get_status(error, &status, &error_str);
-    close_with_status(&exec_ctx, call, status, error_str);
+    close_with_status(exec_ctx, call, status, error_str);
   }
   if (args->cq != NULL) {
     GPR_ASSERT(
@@ -338,12 +339,11 @@ grpc_error *grpc_call_create(const grpc_call_create_args *args,
   }
   if (!grpc_polling_entity_is_empty(&call->pollent)) {
     grpc_call_stack_set_pollset_or_pollset_set(
-        &exec_ctx, CALL_STACK_FROM_CALL(call), &call->pollent);
+        exec_ctx, CALL_STACK_FROM_CALL(call), &call->pollent);
   }
 
-  if (path != NULL) GRPC_MDSTR_UNREF(path);
+  if (path != NULL) GRPC_MDSTR_UNREF(exec_ctx, path);
 
-  grpc_exec_ctx_finish(&exec_ctx);
   GPR_TIMER_END("grpc_call_create", 0);
   return error;
 }
@@ -404,7 +404,7 @@ static void destroy_call(grpc_exec_ctx *exec_ctx, void *call,
   GPR_TIMER_BEGIN("destroy_call", 0);
   for (i = 0; i < 2; i++) {
     grpc_metadata_batch_destroy(
-        &c->metadata_batch[1 /* is_receiving */][i /* is_initial */]);
+        exec_ctx, &c->metadata_batch[1 /* is_receiving */][i /* is_initial */]);
   }
   if (c->receiving_stream != NULL) {
     grpc_byte_stream_destroy(exec_ctx, c->receiving_stream);
@@ -412,11 +412,11 @@ static void destroy_call(grpc_exec_ctx *exec_ctx, void *call,
   gpr_mu_destroy(&c->mu);
   for (i = 0; i < STATUS_SOURCE_COUNT; i++) {
     if (c->status[i].details) {
-      GRPC_MDSTR_UNREF(c->status[i].details);
+      GRPC_MDSTR_UNREF(exec_ctx, c->status[i].details);
     }
   }
   for (ii = 0; ii < c->send_extra_metadata_count; ii++) {
-    GRPC_MDELEM_UNREF(c->send_extra_metadata[ii].md);
+    GRPC_MDELEM_UNREF(exec_ctx, c->send_extra_metadata[ii].md);
   }
   for (i = 0; i < GRPC_CONTEXT_COUNT; i++) {
     if (c->context[i].destroy) {
@@ -446,22 +446,22 @@ static void set_status_code(grpc_call *call, status_source source,
   call->status[source].code = (grpc_status_code)status;
 }
 
-static void set_status_details(grpc_call *call, status_source source,
-                               grpc_mdstr *status) {
+static void set_status_details(grpc_exec_ctx *exec_ctx, grpc_call *call,
+                               status_source source, grpc_mdstr *status) {
   if (call->status[source].details != NULL) {
-    GRPC_MDSTR_UNREF(status);
+    GRPC_MDSTR_UNREF(exec_ctx, status);
   } else {
     call->status[source].details = status;
   }
 }
 
-static void set_status_from_error(grpc_call *call, status_source source,
-                                  grpc_error *error) {
+static void set_status_from_error(grpc_exec_ctx *exec_ctx, grpc_call *call,
+                                  status_source source, grpc_error *error) {
   grpc_status_code status;
   const char *msg;
   grpc_error_get_status(error, &status, &msg);
   set_status_code(call, source, (uint32_t)status);
-  set_status_details(call, source, grpc_mdstr_from_string(msg));
+  set_status_details(exec_ctx, call, source, grpc_mdstr_from_string(msg));
 }
 
 static void set_incoming_compression_algorithm(
@@ -495,7 +495,8 @@ uint32_t grpc_call_test_only_get_message_flags(grpc_call *call) {
 
 static void destroy_encodings_accepted_by_peer(void *p) { return; }
 
-static void set_encodings_accepted_by_peer(grpc_call *call, grpc_mdelem *mdel) {
+static void set_encodings_accepted_by_peer(grpc_exec_ctx *exec_ctx,
+                                           grpc_call *call, grpc_mdelem *mdel) {
   size_t i;
   grpc_compression_algorithm algorithm;
   grpc_slice_buffer accept_encoding_parts;
@@ -535,7 +536,7 @@ static void set_encodings_accepted_by_peer(grpc_call *call, grpc_mdelem *mdel) {
     }
   }
 
-  grpc_slice_buffer_destroy(&accept_encoding_parts);
+  grpc_slice_buffer_destroy_internal(exec_ctx, &accept_encoding_parts);
 
   grpc_mdelem_set_user_data(
       mdel, destroy_encodings_accepted_by_peer,
@@ -593,12 +594,10 @@ static grpc_metadata *get_md_elem(grpc_metadata *metadata,
   return res;
 }
 
-static int prepare_application_metadata(grpc_call *call, int count,
-                                        grpc_metadata *metadata,
-                                        int is_trailing,
-                                        int prepend_extra_metadata,
-                                        grpc_metadata *additional_metadata,
-                                        int additional_metadata_count) {
+static int prepare_application_metadata(
+    grpc_exec_ctx *exec_ctx, grpc_call *call, int count,
+    grpc_metadata *metadata, int is_trailing, int prepend_extra_metadata,
+    grpc_metadata *additional_metadata, int additional_metadata_count) {
   int total_count = count + additional_metadata_count;
   int i;
   grpc_metadata_batch *batch =
@@ -609,7 +608,7 @@ static int prepare_application_metadata(grpc_call *call, int count,
     grpc_linked_mdelem *l = (grpc_linked_mdelem *)&md->internal_data;
     GPR_ASSERT(sizeof(grpc_linked_mdelem) == sizeof(md->internal_data));
     l->md = grpc_mdelem_from_string_and_buffer(
-        md->key, (const uint8_t *)md->value, md->value_length);
+        exec_ctx, md->key, (const uint8_t *)md->value, md->value_length);
     if (!grpc_header_key_is_legal(grpc_mdstr_as_c_string(l->md->key),
                                   GRPC_MDSTR_LENGTH(l->md->key))) {
       gpr_log(GPR_ERROR, "attempt to send invalid metadata key: %s",
@@ -629,7 +628,7 @@ static int prepare_application_metadata(grpc_call *call, int count,
       const grpc_metadata *md =
           get_md_elem(metadata, additional_metadata, j, count);
       grpc_linked_mdelem *l = (grpc_linked_mdelem *)&md->internal_data;
-      GRPC_MDELEM_UNREF(l->md);
+      GRPC_MDELEM_UNREF(exec_ctx, l->md);
     }
     return 0;
   }
@@ -813,7 +812,8 @@ static void send_close(grpc_exec_ctx *exec_ctx, void *tcp, grpc_error *error) {
 
 static grpc_call_error terminate_with_status(grpc_exec_ctx *exec_ctx,
                                              termination_closure *tc) {
-  set_status_from_error(tc->call, STATUS_FROM_API_OVERRIDE, tc->error);
+  set_status_from_error(exec_ctx, tc->call, STATUS_FROM_API_OVERRIDE,
+                        tc->error);
 
   if (tc->type == TC_CANCEL) {
     grpc_closure_init(&tc->closure, send_cancel, tc, grpc_schedule_on_exec_ctx);
@@ -930,7 +930,8 @@ static grpc_compression_algorithm decode_compression(grpc_mdelem *md) {
   return algorithm;
 }
 
-static grpc_mdelem *recv_common_filter(grpc_call *call, grpc_mdelem *elem) {
+static grpc_mdelem *recv_common_filter(grpc_exec_ctx *exec_ctx, grpc_call *call,
+                                       grpc_mdelem *elem) {
   if (elem->key == GRPC_MDSTR_GRPC_STATUS) {
     GPR_TIMER_BEGIN("status", 0);
     set_status_code(call, STATUS_FROM_WIRE, decode_status(elem));
@@ -938,7 +939,8 @@ static grpc_mdelem *recv_common_filter(grpc_call *call, grpc_mdelem *elem) {
     return NULL;
   } else if (elem->key == GRPC_MDSTR_GRPC_MESSAGE) {
     GPR_TIMER_BEGIN("status-details", 0);
-    set_status_details(call, STATUS_FROM_WIRE, GRPC_MDSTR_REF(elem->value));
+    set_status_details(exec_ctx, call, STATUS_FROM_WIRE,
+                       GRPC_MDSTR_REF(elem->value));
     GPR_TIMER_END("status-details", 0);
     return NULL;
   }
@@ -964,9 +966,10 @@ static grpc_mdelem *publish_app_metadata(grpc_call *call, grpc_mdelem *elem,
   return elem;
 }
 
-static grpc_mdelem *recv_initial_filter(void *callp, grpc_mdelem *elem) {
-  grpc_call *call = callp;
-  elem = recv_common_filter(call, elem);
+static grpc_mdelem *recv_initial_filter(grpc_exec_ctx *exec_ctx, void *args,
+                                        grpc_mdelem *elem) {
+  grpc_call *call = args;
+  elem = recv_common_filter(exec_ctx, call, elem);
   if (elem == NULL) {
     return NULL;
   } else if (elem->key == GRPC_MDSTR_GRPC_ENCODING) {
@@ -976,7 +979,7 @@ static grpc_mdelem *recv_initial_filter(void *callp, grpc_mdelem *elem) {
     return NULL;
   } else if (elem->key == GRPC_MDSTR_GRPC_ACCEPT_ENCODING) {
     GPR_TIMER_BEGIN("encodings_accepted_by_peer", 0);
-    set_encodings_accepted_by_peer(call, elem);
+    set_encodings_accepted_by_peer(exec_ctx, call, elem);
     GPR_TIMER_END("encodings_accepted_by_peer", 0);
     return NULL;
   } else {
@@ -984,9 +987,10 @@ static grpc_mdelem *recv_initial_filter(void *callp, grpc_mdelem *elem) {
   }
 }
 
-static grpc_mdelem *recv_trailing_filter(void *callp, grpc_mdelem *elem) {
-  grpc_call *call = callp;
-  elem = recv_common_filter(call, elem);
+static grpc_mdelem *recv_trailing_filter(grpc_exec_ctx *exec_ctx, void *args,
+                                         grpc_mdelem *elem) {
+  grpc_call *call = args;
+  elem = recv_common_filter(exec_ctx, call, elem);
   if (elem == NULL) {
     return NULL;
   } else {
@@ -1236,7 +1240,7 @@ static void receiving_initial_metadata_ready(grpc_exec_ctx *exec_ctx,
   if (error == GRPC_ERROR_NONE) {
     grpc_metadata_batch *md =
         &call->metadata_batch[1 /* is_receiving */][0 /* is_trailing */];
-    grpc_metadata_batch_filter(md, recv_initial_filter, call);
+    grpc_metadata_batch_filter(exec_ctx, md, recv_initial_filter, call);
 
     GPR_TIMER_BEGIN("validate_filtered_metadata", 0);
     validate_filtered_metadata(exec_ctx, bctl);
@@ -1281,14 +1285,15 @@ static void finish_batch(grpc_exec_ctx *exec_ctx, void *bctlp,
   intptr_t status;
   if (error != GRPC_ERROR_NONE &&
       grpc_error_get_int(error, GRPC_ERROR_INT_GRPC_STATUS, &status)) {
-    set_status_from_error(call, STATUS_FROM_CORE, error);
+    set_status_from_error(exec_ctx, call, STATUS_FROM_CORE, error);
   }
 
   if (bctl->send_initial_metadata) {
     if (error != GRPC_ERROR_NONE) {
-      set_status_from_error(call, STATUS_FROM_CORE, error);
+      set_status_from_error(exec_ctx, call, STATUS_FROM_CORE, error);
     }
     grpc_metadata_batch_destroy(
+        exec_ctx,
         &call->metadata_batch[0 /* is_receiving */][0 /* is_trailing */]);
   }
   if (bctl->send_message) {
@@ -1296,12 +1301,13 @@ static void finish_batch(grpc_exec_ctx *exec_ctx, void *bctlp,
   }
   if (bctl->send_final_op) {
     grpc_metadata_batch_destroy(
+        exec_ctx,
         &call->metadata_batch[0 /* is_receiving */][1 /* is_trailing */]);
   }
   if (bctl->recv_final_op) {
     grpc_metadata_batch *md =
         &call->metadata_batch[1 /* is_receiving */][1 /* is_trailing */];
-    grpc_metadata_batch_filter(md, recv_trailing_filter, call);
+    grpc_metadata_batch_filter(exec_ctx, md, recv_trailing_filter, call);
 
     call->received_final_op = true;
     /* propagate cancellation to any interested children */
@@ -1438,7 +1444,7 @@ static grpc_call_error call_start_batch(grpc_exec_ctx *exec_ctx,
         bctl->send_initial_metadata = 1;
         call->sent_initial_metadata = 1;
         if (!prepare_application_metadata(
-                call, (int)op->data.send_initial_metadata.count,
+                exec_ctx, call, (int)op->data.send_initial_metadata.count,
                 op->data.send_initial_metadata.metadata, 0, call->is_client,
                 &compression_md, (int)additional_metadata_count)) {
           error = GRPC_CALL_ERROR_INVALID_METADATA;
@@ -1518,15 +1524,15 @@ static grpc_call_error call_start_batch(grpc_exec_ctx *exec_ctx,
         call->sent_final_op = 1;
         call->send_extra_metadata_count = 1;
         call->send_extra_metadata[0].md = grpc_channel_get_reffed_status_elem(
-            call->channel, op->data.send_status_from_server.status);
+            exec_ctx, call->channel, op->data.send_status_from_server.status);
         if (op->data.send_status_from_server.status_details != NULL) {
           call->send_extra_metadata[1].md = grpc_mdelem_from_metadata_strings(
-              GRPC_MDSTR_GRPC_MESSAGE,
+              exec_ctx, GRPC_MDSTR_GRPC_MESSAGE,
               grpc_mdstr_from_string(
                   op->data.send_status_from_server.status_details));
           call->send_extra_metadata_count++;
           set_status_details(
-              call, STATUS_FROM_API_OVERRIDE,
+              exec_ctx, call, STATUS_FROM_API_OVERRIDE,
               GRPC_MDSTR_REF(call->send_extra_metadata[1].md->value));
         }
         if (op->data.send_status_from_server.status != GRPC_STATUS_OK) {
@@ -1534,7 +1540,7 @@ static grpc_call_error call_start_batch(grpc_exec_ctx *exec_ctx,
                           (uint32_t)op->data.send_status_from_server.status);
         }
         if (!prepare_application_metadata(
-                call,
+                exec_ctx, call,
                 (int)op->data.send_status_from_server.trailing_metadata_count,
                 op->data.send_status_from_server.trailing_metadata, 1, 1, NULL,
                 0)) {
@@ -1665,7 +1671,7 @@ done_with_error:
   /* reverse any mutations that occured */
   if (bctl->send_initial_metadata) {
     call->sent_initial_metadata = 0;
-    grpc_metadata_batch_clear(&call->metadata_batch[0][0]);
+    grpc_metadata_batch_clear(exec_ctx, &call->metadata_batch[0][0]);
   }
   if (bctl->send_message) {
     call->sending_message = 0;
@@ -1673,7 +1679,7 @@ done_with_error:
   }
   if (bctl->send_final_op) {
     call->sent_final_op = 0;
-    grpc_metadata_batch_clear(&call->metadata_batch[0][1]);
+    grpc_metadata_batch_clear(exec_ctx, &call->metadata_batch[0][1]);
   }
   if (bctl->recv_initial_metadata) {
     call->received_initial_metadata = 0;
diff --git a/src/core/lib/surface/call.h b/src/core/lib/surface/call.h
index 18af41b7fb..233340c329 100644
--- a/src/core/lib/surface/call.h
+++ b/src/core/lib/surface/call.h
@@ -70,7 +70,8 @@ typedef struct grpc_call_create_args {
 /* Create a new call based on \a args.
    Regardless of success or failure, always returns a valid new call into *call
    */
-grpc_error *grpc_call_create(const grpc_call_create_args *args,
+grpc_error *grpc_call_create(grpc_exec_ctx *exec_ctx,
+                             const grpc_call_create_args *args,
                              grpc_call **call);
 
 void grpc_call_set_completion_queue(grpc_exec_ctx *exec_ctx, grpc_call *call,
diff --git a/src/core/lib/surface/channel.c b/src/core/lib/surface/channel.c
index 9405015c50..b87295786e 100644
--- a/src/core/lib/surface/channel.c
+++ b/src/core/lib/surface/channel.c
@@ -87,11 +87,12 @@ grpc_channel *grpc_channel_create(grpc_exec_ctx *exec_ctx, const char *target,
                                   grpc_channel_stack_type channel_stack_type,
                                   grpc_transport *optional_transport) {
   grpc_channel_stack_builder *builder = grpc_channel_stack_builder_create();
-  grpc_channel_stack_builder_set_channel_arguments(builder, input_args);
+  grpc_channel_stack_builder_set_channel_arguments(exec_ctx, builder,
+                                                   input_args);
   grpc_channel_stack_builder_set_target(builder, target);
   grpc_channel_stack_builder_set_transport(builder, optional_transport);
   if (!grpc_channel_init_create_stack(exec_ctx, builder, channel_stack_type)) {
-    grpc_channel_stack_builder_destroy(builder);
+    grpc_channel_stack_builder_destroy(exec_ctx, builder);
     return NULL;
   }
   grpc_channel_args *args = grpc_channel_args_copy(
@@ -124,10 +125,10 @@ grpc_channel *grpc_channel_create(grpc_exec_ctx *exec_ctx, const char *target,
       } else {
         if (channel->default_authority) {
           /* setting this takes precedence over anything else */
-          GRPC_MDELEM_UNREF(channel->default_authority);
+          GRPC_MDELEM_UNREF(exec_ctx, channel->default_authority);
         }
-        channel->default_authority =
-            grpc_mdelem_from_strings(":authority", args->args[i].value.string);
+        channel->default_authority = grpc_mdelem_from_strings(
+            exec_ctx, ":authority", args->args[i].value.string);
       }
     } else if (0 ==
                strcmp(args->args[i].key, GRPC_SSL_TARGET_NAME_OVERRIDE_ARG)) {
@@ -142,7 +143,7 @@ grpc_channel *grpc_channel_create(grpc_exec_ctx *exec_ctx, const char *target,
                   GRPC_SSL_TARGET_NAME_OVERRIDE_ARG);
         } else {
           channel->default_authority = grpc_mdelem_from_strings(
-              ":authority", args->args[i].value.string);
+              exec_ctx, ":authority", args->args[i].value.string);
         }
       }
     } else if (0 == strcmp(args->args[i].key,
@@ -169,7 +170,7 @@ grpc_channel *grpc_channel_create(grpc_exec_ctx *exec_ctx, const char *target,
   }
 
 done:
-  grpc_channel_args_destroy(args);
+  grpc_channel_args_destroy(exec_ctx, args);
   return channel;
 }
 
@@ -188,10 +189,10 @@ void grpc_channel_get_info(grpc_channel *channel,
 }
 
 static grpc_call *grpc_channel_create_call_internal(
-    grpc_channel *channel, grpc_call *parent_call, uint32_t propagation_mask,
-    grpc_completion_queue *cq, grpc_pollset_set *pollset_set_alternative,
-    grpc_mdelem *path_mdelem, grpc_mdelem *authority_mdelem,
-    gpr_timespec deadline) {
+    grpc_exec_ctx *exec_ctx, grpc_channel *channel, grpc_call *parent_call,
+    uint32_t propagation_mask, grpc_completion_queue *cq,
+    grpc_pollset_set *pollset_set_alternative, grpc_mdelem *path_mdelem,
+    grpc_mdelem *authority_mdelem, gpr_timespec deadline) {
   grpc_mdelem *send_metadata[2];
   size_t num_metadata = 0;
 
@@ -218,7 +219,7 @@ static grpc_call *grpc_channel_create_call_internal(
   args.send_deadline = deadline;
 
   grpc_call *call;
-  GRPC_LOG_IF_ERROR("call_create", grpc_call_create(&args, &call));
+  GRPC_LOG_IF_ERROR("call_create", grpc_call_create(exec_ctx, &args, &call));
   return call;
 }
 
@@ -239,26 +240,30 @@ grpc_call *grpc_channel_create_call(grpc_channel *channel,
       (channel, parent_call, (unsigned)propagation_mask, cq, method, host,
        deadline.tv_sec, deadline.tv_nsec, (int)deadline.clock_type, reserved));
   GPR_ASSERT(!reserved);
-  return grpc_channel_create_call_internal(
-      channel, parent_call, propagation_mask, cq, NULL,
-      grpc_mdelem_from_metadata_strings(GRPC_MDSTR_PATH,
+  grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
+  grpc_call *call = grpc_channel_create_call_internal(
+      &exec_ctx, channel, parent_call, propagation_mask, cq, NULL,
+      grpc_mdelem_from_metadata_strings(&exec_ctx, GRPC_MDSTR_PATH,
                                         grpc_mdstr_from_string(method)),
-      host ? grpc_mdelem_from_metadata_strings(GRPC_MDSTR_AUTHORITY,
+      host ? grpc_mdelem_from_metadata_strings(&exec_ctx, GRPC_MDSTR_AUTHORITY,
                                                grpc_mdstr_from_string(host))
            : NULL,
       deadline);
+  grpc_exec_ctx_finish(&exec_ctx);
+  return call;
 }
 
 grpc_call *grpc_channel_create_pollset_set_call(
-    grpc_channel *channel, grpc_call *parent_call, uint32_t propagation_mask,
-    grpc_pollset_set *pollset_set, const char *method, const char *host,
-    gpr_timespec deadline, void *reserved) {
+    grpc_exec_ctx *exec_ctx, grpc_channel *channel, grpc_call *parent_call,
+    uint32_t propagation_mask, grpc_pollset_set *pollset_set,
+    const char *method, const char *host, gpr_timespec deadline,
+    void *reserved) {
   GPR_ASSERT(!reserved);
   return grpc_channel_create_call_internal(
-      channel, parent_call, propagation_mask, NULL, pollset_set,
-      grpc_mdelem_from_metadata_strings(GRPC_MDSTR_PATH,
+      exec_ctx, channel, parent_call, propagation_mask, NULL, pollset_set,
+      grpc_mdelem_from_metadata_strings(exec_ctx, GRPC_MDSTR_PATH,
                                         grpc_mdstr_from_string(method)),
-      host ? grpc_mdelem_from_metadata_strings(GRPC_MDSTR_AUTHORITY,
+      host ? grpc_mdelem_from_metadata_strings(exec_ctx, GRPC_MDSTR_AUTHORITY,
                                                grpc_mdstr_from_string(host))
            : NULL,
       deadline);
@@ -271,15 +276,18 @@ void *grpc_channel_register_call(grpc_channel *channel, const char *method,
       "grpc_channel_register_call(channel=%p, method=%s, host=%s, reserved=%p)",
       4, (channel, method, host, reserved));
   GPR_ASSERT(!reserved);
-  rc->path = grpc_mdelem_from_metadata_strings(GRPC_MDSTR_PATH,
+  grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
+  rc->path = grpc_mdelem_from_metadata_strings(&exec_ctx, GRPC_MDSTR_PATH,
                                                grpc_mdstr_from_string(method));
-  rc->authority = host ? grpc_mdelem_from_metadata_strings(
-                             GRPC_MDSTR_AUTHORITY, grpc_mdstr_from_string(host))
-                       : NULL;
+  rc->authority =
+      host ? grpc_mdelem_from_metadata_strings(&exec_ctx, GRPC_MDSTR_AUTHORITY,
+                                               grpc_mdstr_from_string(host))
+           : NULL;
   gpr_mu_lock(&channel->registered_call_mu);
   rc->next = channel->registered_calls;
   channel->registered_calls = rc;
   gpr_mu_unlock(&channel->registered_call_mu);
+  grpc_exec_ctx_finish(&exec_ctx);
   return rc;
 }
 
@@ -299,10 +307,13 @@ grpc_call *grpc_channel_create_registered_call(
           registered_call_handle, deadline.tv_sec, deadline.tv_nsec,
           (int)deadline.clock_type, reserved));
   GPR_ASSERT(!reserved);
-  return grpc_channel_create_call_internal(
-      channel, parent_call, propagation_mask, completion_queue, NULL,
+  grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
+  grpc_call *call = grpc_channel_create_call_internal(
+      &exec_ctx, channel, parent_call, propagation_mask, completion_queue, NULL,
       GRPC_MDELEM_REF(rc->path),
       rc->authority ? GRPC_MDELEM_REF(rc->authority) : NULL, deadline);
+  grpc_exec_ctx_finish(&exec_ctx);
+  return call;
 }
 
 #ifdef GRPC_STREAM_REFCOUNT_DEBUG
@@ -328,14 +339,14 @@ static void destroy_channel(grpc_exec_ctx *exec_ctx, void *arg,
   while (channel->registered_calls) {
     registered_call *rc = channel->registered_calls;
     channel->registered_calls = rc->next;
-    GRPC_MDELEM_UNREF(rc->path);
+    GRPC_MDELEM_UNREF(exec_ctx, rc->path);
     if (rc->authority) {
-      GRPC_MDELEM_UNREF(rc->authority);
+      GRPC_MDELEM_UNREF(exec_ctx, rc->authority);
     }
     gpr_free(rc);
   }
   if (channel->default_authority != NULL) {
-    GRPC_MDELEM_UNREF(channel->default_authority);
+    GRPC_MDELEM_UNREF(exec_ctx, channel->default_authority);
   }
   gpr_mu_destroy(&channel->registered_call_mu);
   gpr_free(channel->target);
@@ -365,7 +376,8 @@ grpc_compression_options grpc_channel_compression_options(
   return channel->compression_options;
 }
 
-grpc_mdelem *grpc_channel_get_reffed_status_elem(grpc_channel *channel, int i) {
+grpc_mdelem *grpc_channel_get_reffed_status_elem(grpc_exec_ctx *exec_ctx,
+                                                 grpc_channel *channel, int i) {
   char tmp[GPR_LTOA_MIN_BUFSIZE];
   switch (i) {
     case 0:
@@ -376,6 +388,6 @@ grpc_mdelem *grpc_channel_get_reffed_status_elem(grpc_channel *channel, int i) {
       return GRPC_MDELEM_GRPC_STATUS_2;
   }
   gpr_ltoa(i, tmp);
-  return grpc_mdelem_from_metadata_strings(GRPC_MDSTR_GRPC_STATUS,
+  return grpc_mdelem_from_metadata_strings(exec_ctx, GRPC_MDSTR_GRPC_STATUS,
                                            grpc_mdstr_from_string(tmp));
 }
diff --git a/src/core/lib/surface/channel.h b/src/core/lib/surface/channel.h
index 23cc8656ca..2ebadb7a15 100644
--- a/src/core/lib/surface/channel.h
+++ b/src/core/lib/surface/channel.h
@@ -51,9 +51,10 @@ grpc_channel *grpc_channel_create(grpc_exec_ctx *exec_ctx, const char *target,
     properties from the server call to this new client call, depending on the
     value of \a propagation_mask (see propagation_bits.h for possible values) */
 grpc_call *grpc_channel_create_pollset_set_call(
-    grpc_channel *channel, grpc_call *parent_call, uint32_t propagation_mask,
-    grpc_pollset_set *pollset_set, const char *method, const char *host,
-    gpr_timespec deadline, void *reserved);
+    grpc_exec_ctx *exec_ctx, grpc_channel *channel, grpc_call *parent_call,
+    uint32_t propagation_mask, grpc_pollset_set *pollset_set,
+    const char *method, const char *host, gpr_timespec deadline,
+    void *reserved);
 
 /** Get a (borrowed) pointer to this channels underlying channel stack */
 grpc_channel_stack *grpc_channel_get_channel_stack(grpc_channel *channel);
@@ -62,7 +63,8 @@ grpc_channel_stack *grpc_channel_get_channel_stack(grpc_channel *channel);
     status_code.
 
     The returned elem is owned by the caller. */
-grpc_mdelem *grpc_channel_get_reffed_status_elem(grpc_channel *channel,
+grpc_mdelem *grpc_channel_get_reffed_status_elem(grpc_exec_ctx *exec_ctx,
+                                                 grpc_channel *channel,
                                                  int status_code);
 
 #ifdef GRPC_STREAM_REFCOUNT_DEBUG
diff --git a/src/core/lib/surface/channel_init.c b/src/core/lib/surface/channel_init.c
index 0627b34479..7acb444d9b 100644
--- a/src/core/lib/surface/channel_init.c
+++ b/src/core/lib/surface/channel_init.c
@@ -131,7 +131,7 @@ bool grpc_channel_init_create_stack(grpc_exec_ctx *exec_ctx,
 
   for (size_t i = 0; i < g_slots[type].num_slots; i++) {
     const stage_slot *slot = &g_slots[type].slots[i];
-    if (!slot->fn(builder, slot->arg)) {
+    if (!slot->fn(exec_ctx, builder, slot->arg)) {
       return false;
     }
   }
diff --git a/src/core/lib/surface/channel_init.h b/src/core/lib/surface/channel_init.h
index b53f2aefb9..411f5eae18 100644
--- a/src/core/lib/surface/channel_init.h
+++ b/src/core/lib/surface/channel_init.h
@@ -51,7 +51,8 @@ extern "C" {
 
 /// One stage of mutation: call functions against \a builder to influence the
 /// finally constructed channel stack
-typedef bool (*grpc_channel_init_stage)(grpc_channel_stack_builder *builder,
+typedef bool (*grpc_channel_init_stage)(grpc_exec_ctx *exec_ctx,
+                                        grpc_channel_stack_builder *builder,
                                         void *arg);
 
 /// Global initialization of the system
diff --git a/src/core/lib/surface/init.c b/src/core/lib/surface/init.c
index 7903f57a68..f61bf1582e 100644
--- a/src/core/lib/surface/init.c
+++ b/src/core/lib/surface/init.c
@@ -44,6 +44,7 @@
 #include "src/core/lib/channel/compress_filter.h"
 #include "src/core/lib/channel/connected_channel.h"
 #include "src/core/lib/channel/deadline_filter.h"
+#include "src/core/lib/channel/handshaker_registry.h"
 #include "src/core/lib/channel/http_client_filter.h"
 #include "src/core/lib/channel/http_server_filter.h"
 #include "src/core/lib/channel/message_size_filter.h"
@@ -80,17 +81,20 @@ static void do_basic_init(void) {
   g_initializations = 0;
 }
 
-static bool append_filter(grpc_channel_stack_builder *builder, void *arg) {
+static bool append_filter(grpc_exec_ctx *exec_ctx,
+                          grpc_channel_stack_builder *builder, void *arg) {
   return grpc_channel_stack_builder_append_filter(
       builder, (const grpc_channel_filter *)arg, NULL, NULL);
 }
 
-static bool prepend_filter(grpc_channel_stack_builder *builder, void *arg) {
+static bool prepend_filter(grpc_exec_ctx *exec_ctx,
+                           grpc_channel_stack_builder *builder, void *arg) {
   return grpc_channel_stack_builder_prepend_filter(
       builder, (const grpc_channel_filter *)arg, NULL, NULL);
 }
 
-static bool maybe_add_http_filter(grpc_channel_stack_builder *builder,
+static bool maybe_add_http_filter(grpc_exec_ctx *exec_ctx,
+                                  grpc_channel_stack_builder *builder,
                                   void *arg) {
   grpc_transport *t = grpc_channel_stack_builder_get_transport(builder);
   if (t && strstr(t->vtable->name, "http")) {
@@ -201,6 +205,8 @@ void grpc_init(void) {
     grpc_executor_init();
     gpr_timers_global_init();
     grpc_cq_global_init();
+    grpc_handshaker_factory_registry_init();
+    grpc_security_init();
     for (i = 0; i < g_number_of_plugins; i++) {
       if (g_all_of_the_plugins[i].init != NULL) {
         g_all_of_the_plugins[i].init();
@@ -221,11 +227,12 @@ void grpc_init(void) {
 void grpc_shutdown(void) {
   int i;
   GRPC_API_TRACE("grpc_shutdown(void)", 0, ());
+  grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
   gpr_mu_lock(&g_init_mu);
   if (--g_initializations == 0) {
-    grpc_executor_shutdown();
+    grpc_executor_shutdown(&exec_ctx);
     grpc_cq_global_shutdown();
-    grpc_iomgr_shutdown();
+    grpc_iomgr_shutdown(&exec_ctx);
     gpr_timers_global_destroy();
     grpc_tracer_shutdown();
     for (i = g_number_of_plugins; i >= 0; i--) {
@@ -233,9 +240,11 @@ void grpc_shutdown(void) {
         g_all_of_the_plugins[i].destroy();
       }
     }
-    grpc_mdctx_global_shutdown();
+    grpc_mdctx_global_shutdown(&exec_ctx);
+    grpc_handshaker_factory_registry_shutdown(&exec_ctx);
   }
   gpr_mu_unlock(&g_init_mu);
+  grpc_exec_ctx_finish(&exec_ctx);
 }
 
 int grpc_is_initialized(void) {
diff --git a/src/core/lib/surface/init.h b/src/core/lib/surface/init.h
index b1bf57c10d..3d1c528be0 100644
--- a/src/core/lib/surface/init.h
+++ b/src/core/lib/surface/init.h
@@ -36,6 +36,7 @@
 
 void grpc_register_security_filters(void);
 void grpc_security_pre_init(void);
+void grpc_security_init(void);
 int grpc_is_initialized(void);
 
 #endif /* GRPC_CORE_LIB_SURFACE_INIT_H */
diff --git a/src/core/lib/surface/init_secure.c b/src/core/lib/surface/init_secure.c
index 7ee7b51568..a44407d3bb 100644
--- a/src/core/lib/surface/init_secure.c
+++ b/src/core/lib/surface/init_secure.c
@@ -41,6 +41,7 @@
 #include "src/core/lib/security/transport/auth_filters.h"
 #include "src/core/lib/security/transport/secure_endpoint.h"
 #include "src/core/lib/security/transport/security_connector.h"
+#include "src/core/lib/security/transport/security_handshaker.h"
 #include "src/core/lib/surface/channel_init.h"
 #include "src/core/lib/tsi/transport_security_interface.h"
 
@@ -50,7 +51,7 @@ void grpc_security_pre_init(void) {
 }
 
 static bool maybe_prepend_client_auth_filter(
-    grpc_channel_stack_builder *builder, void *arg) {
+    grpc_exec_ctx *exec_ctx, grpc_channel_stack_builder *builder, void *arg) {
   const grpc_channel_args *args =
       grpc_channel_stack_builder_get_channel_arguments(builder);
   if (args) {
@@ -65,7 +66,7 @@ static bool maybe_prepend_client_auth_filter(
 }
 
 static bool maybe_prepend_server_auth_filter(
-    grpc_channel_stack_builder *builder, void *arg) {
+    grpc_exec_ctx *exec_ctx, grpc_channel_stack_builder *builder, void *arg) {
   const grpc_channel_args *args =
       grpc_channel_stack_builder_get_channel_arguments(builder);
   if (args) {
@@ -87,3 +88,5 @@ void grpc_register_security_filters(void) {
   grpc_channel_init_register_stage(GRPC_SERVER_CHANNEL, INT_MAX,
                                    maybe_prepend_server_auth_filter, NULL);
 }
+
+void grpc_security_init() { grpc_security_register_handshaker_factories(); }
diff --git a/src/core/lib/surface/init_unsecure.c b/src/core/lib/surface/init_unsecure.c
index f952739e0a..dbc9223ae0 100644
--- a/src/core/lib/surface/init_unsecure.c
+++ b/src/core/lib/surface/init_unsecure.c
@@ -36,3 +36,5 @@
 void grpc_security_pre_init(void) {}
 
 void grpc_register_security_filters(void) {}
+
+void grpc_security_init(void) {}
diff --git a/src/core/lib/surface/lame_client.c b/src/core/lib/surface/lame_client.c
index f1ad13711a..ae1eac09a9 100644
--- a/src/core/lib/surface/lame_client.c
+++ b/src/core/lib/surface/lame_client.c
@@ -55,14 +55,15 @@ typedef struct {
   const char *error_message;
 } channel_data;
 
-static void fill_metadata(grpc_call_element *elem, grpc_metadata_batch *mdb) {
+static void fill_metadata(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
+                          grpc_metadata_batch *mdb) {
   call_data *calld = elem->call_data;
   channel_data *chand = elem->channel_data;
   char tmp[GPR_LTOA_MIN_BUFSIZE];
   gpr_ltoa(chand->error_code, tmp);
-  calld->status.md = grpc_mdelem_from_strings("grpc-status", tmp);
+  calld->status.md = grpc_mdelem_from_strings(exec_ctx, "grpc-status", tmp);
   calld->details.md =
-      grpc_mdelem_from_strings("grpc-message", chand->error_message);
+      grpc_mdelem_from_strings(exec_ctx, "grpc-message", chand->error_message);
   calld->status.prev = calld->details.next = NULL;
   calld->status.next = &calld->details;
   calld->details.prev = &calld->status;
@@ -76,9 +77,9 @@ static void lame_start_transport_stream_op(grpc_exec_ctx *exec_ctx,
                                            grpc_transport_stream_op *op) {
   GRPC_CALL_LOG_OP(GPR_INFO, elem, op);
   if (op->recv_initial_metadata != NULL) {
-    fill_metadata(elem, op->recv_initial_metadata);
+    fill_metadata(exec_ctx, elem, op->recv_initial_metadata);
   } else if (op->recv_trailing_metadata != NULL) {
-    fill_metadata(elem, op->recv_trailing_metadata);
+    fill_metadata(exec_ctx, elem, op->recv_trailing_metadata);
   }
   grpc_transport_stream_op_finish_with_failure(
       exec_ctx, op, GRPC_ERROR_CREATE("lame client channel"));
diff --git a/src/core/lib/surface/server.c b/src/core/lib/surface/server.c
index 78699e9e65..addb7c4fbc 100644
--- a/src/core/lib/surface/server.c
+++ b/src/core/lib/surface/server.c
@@ -45,6 +45,7 @@
 #include "src/core/lib/channel/channel_args.h"
 #include "src/core/lib/channel/connected_channel.h"
 #include "src/core/lib/iomgr/iomgr.h"
+#include "src/core/lib/slice/slice_internal.h"
 #include "src/core/lib/support/stack_lockfree.h"
 #include "src/core/lib/support/string.h"
 #include "src/core/lib/surface/api_trace.h"
@@ -271,7 +272,7 @@ struct shutdown_cleanup_args {
 static void shutdown_cleanup(grpc_exec_ctx *exec_ctx, void *arg,
                              grpc_error *error) {
   struct shutdown_cleanup_args *a = arg;
-  grpc_slice_unref(a->slice);
+  grpc_slice_unref_internal(exec_ctx, a->slice);
   gpr_free(a);
 }
 
@@ -380,7 +381,7 @@ static void server_ref(grpc_server *server) {
 static void server_delete(grpc_exec_ctx *exec_ctx, grpc_server *server) {
   registered_method *rm;
   size_t i;
-  grpc_channel_args_destroy(server->channel_args);
+  grpc_channel_args_destroy(exec_ctx, server->channel_args);
   gpr_mu_destroy(&server->mu_global);
   gpr_mu_destroy(&server->mu_call);
   while ((rm = server->registered_methods) != NULL) {
@@ -743,7 +744,8 @@ static void maybe_finish_shutdown(grpc_exec_ctx *exec_ctx,
   }
 }
 
-static grpc_mdelem *server_filter(void *user_data, grpc_mdelem *md) {
+static grpc_mdelem *server_filter(grpc_exec_ctx *exec_ctx, void *user_data,
+                                  grpc_mdelem *md) {
   grpc_call_element *elem = user_data;
   call_data *calld = elem->call_data;
   if (md->key == GRPC_MDSTR_PATH) {
@@ -767,7 +769,8 @@ static void server_on_recv_initial_metadata(grpc_exec_ctx *exec_ctx, void *ptr,
   gpr_timespec op_deadline;
 
   GRPC_ERROR_REF(error);
-  grpc_metadata_batch_filter(calld->recv_initial_metadata, server_filter, elem);
+  grpc_metadata_batch_filter(exec_ctx, calld->recv_initial_metadata,
+                             server_filter, elem);
   op_deadline = calld->recv_initial_metadata->deadline;
   if (0 != gpr_time_cmp(op_deadline, gpr_inf_future(op_deadline.clock_type))) {
     calld->deadline = op_deadline;
@@ -842,7 +845,7 @@ static void accept_stream(grpc_exec_ctx *exec_ctx, void *cd,
   args.server_transport_data = transport_server_data;
   args.send_deadline = gpr_inf_future(GPR_CLOCK_MONOTONIC);
   grpc_call *call;
-  grpc_error *error = grpc_call_create(&args, &call);
+  grpc_error *error = grpc_call_create(exec_ctx, &args, &call);
   grpc_call_element *elem =
       grpc_call_stack_element(grpc_call_get_call_stack(call), 0);
   if (error != GRPC_ERROR_NONE) {
@@ -908,10 +911,10 @@ static void destroy_call_elem(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
   GPR_ASSERT(calld->state != PENDING);
 
   if (calld->host) {
-    GRPC_MDSTR_UNREF(calld->host);
+    GRPC_MDSTR_UNREF(exec_ctx, calld->host);
   }
   if (calld->path) {
-    GRPC_MDSTR_UNREF(calld->path);
+    GRPC_MDSTR_UNREF(exec_ctx, calld->path);
   }
   grpc_metadata_array_destroy(&calld->initial_metadata);
 
@@ -944,10 +947,10 @@ static void destroy_channel_elem(grpc_exec_ctx *exec_ctx,
   if (chand->registered_methods) {
     for (i = 0; i < chand->registered_method_slots; i++) {
       if (chand->registered_methods[i].method) {
-        GRPC_MDSTR_UNREF(chand->registered_methods[i].method);
+        GRPC_MDSTR_UNREF(exec_ctx, chand->registered_methods[i].method);
       }
       if (chand->registered_methods[i].host) {
-        GRPC_MDSTR_UNREF(chand->registered_methods[i].host);
+        GRPC_MDSTR_UNREF(exec_ctx, chand->registered_methods[i].host);
       }
     }
     gpr_free(chand->registered_methods);
diff --git a/src/core/lib/transport/README.md b/src/core/lib/transport/README.md
new file mode 100644
index 0000000000..e7e135edeb
--- /dev/null
+++ b/src/core/lib/transport/README.md
@@ -0,0 +1,7 @@
+# Transport
+
+Common implementation details for gRPC Transports.
+
+Transports multiplex messages across some single connection. In ext/ there are
+implementations atop [a custom http2 implementation](/src/core/ext/transport/chttp2/README.md)
+and atop [cronet](/src/core/ext/transport/cronet/README.md).
diff --git a/src/core/lib/transport/byte_stream.c b/src/core/lib/transport/byte_stream.c
index 2f1d7b7c60..4d4206189e 100644
--- a/src/core/lib/transport/byte_stream.c
+++ b/src/core/lib/transport/byte_stream.c
@@ -37,6 +37,8 @@
 
 #include <grpc/support/log.h>
 
+#include "src/core/lib/slice/slice_internal.h"
+
 int grpc_byte_stream_next(grpc_exec_ctx *exec_ctx,
                           grpc_byte_stream *byte_stream, grpc_slice *slice,
                           size_t max_size_hint, grpc_closure *on_complete) {
@@ -57,7 +59,8 @@ static int slice_buffer_stream_next(grpc_exec_ctx *exec_ctx,
                                     grpc_closure *on_complete) {
   grpc_slice_buffer_stream *stream = (grpc_slice_buffer_stream *)byte_stream;
   GPR_ASSERT(stream->cursor < stream->backing_buffer->count);
-  *slice = grpc_slice_ref(stream->backing_buffer->slices[stream->cursor]);
+  *slice =
+      grpc_slice_ref_internal(stream->backing_buffer->slices[stream->cursor]);
   stream->cursor++;
   return 1;
 }
diff --git a/src/core/lib/transport/mdstr_hash_table.c b/src/core/lib/transport/mdstr_hash_table.c
index 3d01e56df7..2791bf653b 100644
--- a/src/core/lib/transport/mdstr_hash_table.c
+++ b/src/core/lib/transport/mdstr_hash_table.c
@@ -94,13 +94,14 @@ grpc_mdstr_hash_table* grpc_mdstr_hash_table_ref(grpc_mdstr_hash_table* table) {
   return table;
 }
 
-void grpc_mdstr_hash_table_unref(grpc_mdstr_hash_table* table) {
+void grpc_mdstr_hash_table_unref(grpc_exec_ctx* exec_ctx,
+                                 grpc_mdstr_hash_table* table) {
   if (table != NULL && gpr_unref(&table->refs)) {
     for (size_t i = 0; i < table->size; ++i) {
       grpc_mdstr_hash_table_entry* entry = &table->entries[i];
       if (entry->key != NULL) {
-        GRPC_MDSTR_UNREF(entry->key);
-        entry->vtable->destroy_value(entry->value);
+        GRPC_MDSTR_UNREF(exec_ctx, entry->key);
+        entry->vtable->destroy_value(exec_ctx, entry->value);
       }
     }
     gpr_free(table->entries);
diff --git a/src/core/lib/transport/mdstr_hash_table.h b/src/core/lib/transport/mdstr_hash_table.h
index 8982ec3a8d..57f497ee27 100644
--- a/src/core/lib/transport/mdstr_hash_table.h
+++ b/src/core/lib/transport/mdstr_hash_table.h
@@ -49,7 +49,7 @@
 typedef struct grpc_mdstr_hash_table grpc_mdstr_hash_table;
 
 typedef struct grpc_mdstr_hash_table_vtable {
-  void (*destroy_value)(void* value);
+  void (*destroy_value)(grpc_exec_ctx* exec_ctx, void* value);
   void* (*copy_value)(void* value);
 } grpc_mdstr_hash_table_vtable;
 
@@ -66,7 +66,8 @@ grpc_mdstr_hash_table* grpc_mdstr_hash_table_create(
     size_t num_entries, grpc_mdstr_hash_table_entry* entries);
 
 grpc_mdstr_hash_table* grpc_mdstr_hash_table_ref(grpc_mdstr_hash_table* table);
-void grpc_mdstr_hash_table_unref(grpc_mdstr_hash_table* table);
+void grpc_mdstr_hash_table_unref(grpc_exec_ctx* exec_ctx,
+                                 grpc_mdstr_hash_table* table);
 
 /** Returns the value from \a table associated with \a key.
     Returns NULL if \a key is not found. */
diff --git a/src/core/lib/transport/metadata.c b/src/core/lib/transport/metadata.c
index fac19b91d9..54c39df6a7 100644
--- a/src/core/lib/transport/metadata.c
+++ b/src/core/lib/transport/metadata.c
@@ -47,6 +47,7 @@
 
 #include "src/core/lib/iomgr/iomgr_internal.h"
 #include "src/core/lib/profiling/timers.h"
+#include "src/core/lib/slice/slice_internal.h"
 #include "src/core/lib/support/murmur_hash.h"
 #include "src/core/lib/support/string.h"
 #include "src/core/lib/transport/static_metadata.h"
@@ -153,7 +154,7 @@ static size_t g_static_mdtab_maxprobe;
 static strtab_shard g_strtab_shard[STRTAB_SHARD_COUNT];
 static mdtab_shard g_mdtab_shard[MDTAB_SHARD_COUNT];
 
-static void gc_mdtab(mdtab_shard *shard);
+static void gc_mdtab(grpc_exec_ctx *exec_ctx, mdtab_shard *shard);
 
 void grpc_test_only_set_metadata_hash_seed(uint32_t seed) {
   g_hash_seed = seed;
@@ -227,12 +228,12 @@ void grpc_mdctx_global_init(void) {
   }
 }
 
-void grpc_mdctx_global_shutdown(void) {
+void grpc_mdctx_global_shutdown(grpc_exec_ctx *exec_ctx) {
   size_t i;
   for (i = 0; i < MDTAB_SHARD_COUNT; i++) {
     mdtab_shard *shard = &g_mdtab_shard[i];
     gpr_mu_destroy(&shard->mu);
-    gc_mdtab(shard);
+    gc_mdtab(exec_ctx, shard);
     /* TODO(ctiller): GPR_ASSERT(shard->count == 0); */
     if (shard->count != 0) {
       gpr_log(GPR_DEBUG, "WARNING: %" PRIuPTR " metadata elements were leaked",
@@ -316,12 +317,13 @@ static void grow_strtab(strtab_shard *shard) {
   GPR_TIMER_END("grow_strtab", 0);
 }
 
-static void internal_destroy_string(strtab_shard *shard, internal_string *is) {
+static void internal_destroy_string(grpc_exec_ctx *exec_ctx,
+                                    strtab_shard *shard, internal_string *is) {
   internal_string **prev_next;
   internal_string *cur;
   GPR_TIMER_BEGIN("internal_destroy_string", 0);
   if (is->has_base64_and_huffman_encoded) {
-    grpc_slice_unref(is->base64_and_huffman);
+    grpc_slice_unref_internal(exec_ctx, is->base64_and_huffman);
   }
   for (prev_next = &shard->strs[TABLE_IDX(is->hash, LOG2_STRTAB_SHARD_COUNT,
                                           shard->capacity)],
@@ -340,20 +342,20 @@ static void slice_ref(void *p) {
   GRPC_MDSTR_REF((grpc_mdstr *)(is));
 }
 
-static void slice_unref(void *p) {
+static void slice_unref(grpc_exec_ctx *exec_ctx, void *p) {
   internal_string *is =
       (internal_string *)((char *)p - offsetof(internal_string, refcount));
-  GRPC_MDSTR_UNREF((grpc_mdstr *)(is));
+  GRPC_MDSTR_UNREF(exec_ctx, (grpc_mdstr *)(is));
 }
 
 grpc_mdstr *grpc_mdstr_from_string(const char *str) {
   return grpc_mdstr_from_buffer((const uint8_t *)str, strlen(str));
 }
 
-grpc_mdstr *grpc_mdstr_from_slice(grpc_slice slice) {
+grpc_mdstr *grpc_mdstr_from_slice(grpc_exec_ctx *exec_ctx, grpc_slice slice) {
   grpc_mdstr *result = grpc_mdstr_from_buffer(GRPC_SLICE_START_PTR(slice),
                                               GRPC_SLICE_LENGTH(slice));
-  grpc_slice_unref(slice);
+  grpc_slice_unref_internal(exec_ctx, slice);
   return result;
 }
 
@@ -444,7 +446,7 @@ grpc_mdstr *grpc_mdstr_from_buffer(const uint8_t *buf, size_t length) {
   return (grpc_mdstr *)s;
 }
 
-static void gc_mdtab(mdtab_shard *shard) {
+static void gc_mdtab(grpc_exec_ctx *exec_ctx, mdtab_shard *shard) {
   size_t i;
   internal_metadata **prev_next;
   internal_metadata *md, *next;
@@ -457,8 +459,8 @@ static void gc_mdtab(mdtab_shard *shard) {
       void *user_data = (void *)gpr_atm_no_barrier_load(&md->user_data);
       next = md->bucket_next;
       if (gpr_atm_acq_load(&md->refcnt) == 0) {
-        GRPC_MDSTR_UNREF((grpc_mdstr *)md->key);
-        GRPC_MDSTR_UNREF((grpc_mdstr *)md->value);
+        GRPC_MDSTR_UNREF(exec_ctx, (grpc_mdstr *)md->key);
+        GRPC_MDSTR_UNREF(exec_ctx, (grpc_mdstr *)md->value);
         if (md->user_data) {
           ((destroy_user_data_func)gpr_atm_no_barrier_load(
               &md->destroy_user_data))(user_data);
@@ -506,16 +508,17 @@ static void grow_mdtab(mdtab_shard *shard) {
   GPR_TIMER_END("grow_mdtab", 0);
 }
 
-static void rehash_mdtab(mdtab_shard *shard) {
+static void rehash_mdtab(grpc_exec_ctx *exec_ctx, mdtab_shard *shard) {
   if (gpr_atm_no_barrier_load(&shard->free_estimate) >
       (gpr_atm)(shard->capacity / 4)) {
-    gc_mdtab(shard);
+    gc_mdtab(exec_ctx, shard);
   } else {
     grow_mdtab(shard);
   }
 }
 
-grpc_mdelem *grpc_mdelem_from_metadata_strings(grpc_mdstr *mkey,
+grpc_mdelem *grpc_mdelem_from_metadata_strings(grpc_exec_ctx *exec_ctx,
+                                               grpc_mdstr *mkey,
                                                grpc_mdstr *mvalue) {
   internal_string *key = (internal_string *)mkey;
   internal_string *value = (internal_string *)mvalue;
@@ -547,8 +550,8 @@ grpc_mdelem *grpc_mdelem_from_metadata_strings(grpc_mdstr *mkey,
   for (md = shard->elems[idx]; md; md = md->bucket_next) {
     if (md->key == key && md->value == value) {
       REF_MD_LOCKED(shard, md);
-      GRPC_MDSTR_UNREF((grpc_mdstr *)key);
-      GRPC_MDSTR_UNREF((grpc_mdstr *)value);
+      GRPC_MDSTR_UNREF(exec_ctx, (grpc_mdstr *)key);
+      GRPC_MDSTR_UNREF(exec_ctx, (grpc_mdstr *)value);
       gpr_mu_unlock(&shard->mu);
       GPR_TIMER_END("grpc_mdelem_from_metadata_strings", 0);
       return (grpc_mdelem *)md;
@@ -574,7 +577,7 @@ grpc_mdelem *grpc_mdelem_from_metadata_strings(grpc_mdstr *mkey,
   shard->count++;
 
   if (shard->count > shard->capacity * 2) {
-    rehash_mdtab(shard);
+    rehash_mdtab(exec_ctx, shard);
   }
 
   gpr_mu_unlock(&shard->mu);
@@ -584,21 +587,26 @@ grpc_mdelem *grpc_mdelem_from_metadata_strings(grpc_mdstr *mkey,
   return (grpc_mdelem *)md;
 }
 
-grpc_mdelem *grpc_mdelem_from_strings(const char *key, const char *value) {
-  return grpc_mdelem_from_metadata_strings(grpc_mdstr_from_string(key),
-                                           grpc_mdstr_from_string(value));
+grpc_mdelem *grpc_mdelem_from_strings(grpc_exec_ctx *exec_ctx, const char *key,
+                                      const char *value) {
+  return grpc_mdelem_from_metadata_strings(
+      exec_ctx, grpc_mdstr_from_string(key), grpc_mdstr_from_string(value));
 }
 
-grpc_mdelem *grpc_mdelem_from_slices(grpc_slice key, grpc_slice value) {
-  return grpc_mdelem_from_metadata_strings(grpc_mdstr_from_slice(key),
-                                           grpc_mdstr_from_slice(value));
+grpc_mdelem *grpc_mdelem_from_slices(grpc_exec_ctx *exec_ctx, grpc_slice key,
+                                     grpc_slice value) {
+  return grpc_mdelem_from_metadata_strings(
+      exec_ctx, grpc_mdstr_from_slice(exec_ctx, key),
+      grpc_mdstr_from_slice(exec_ctx, value));
 }
 
-grpc_mdelem *grpc_mdelem_from_string_and_buffer(const char *key,
+grpc_mdelem *grpc_mdelem_from_string_and_buffer(grpc_exec_ctx *exec_ctx,
+                                                const char *key,
                                                 const uint8_t *value,
                                                 size_t value_length) {
   return grpc_mdelem_from_metadata_strings(
-      grpc_mdstr_from_string(key), grpc_mdstr_from_buffer(value, value_length));
+      exec_ctx, grpc_mdstr_from_string(key),
+      grpc_mdstr_from_buffer(value, value_length));
 }
 
 static size_t get_base64_encoded_size(size_t raw_length) {
@@ -654,7 +662,7 @@ grpc_mdelem *grpc_mdelem_ref(grpc_mdelem *gmd DEBUG_ARGS) {
   return gmd;
 }
 
-void grpc_mdelem_unref(grpc_mdelem *gmd DEBUG_ARGS) {
+void grpc_mdelem_unref(grpc_exec_ctx *exec_ctx, grpc_mdelem *gmd DEBUG_ARGS) {
   internal_metadata *md = (internal_metadata *)gmd;
   if (!md) return;
   if (is_mdelem_static(gmd)) return;
@@ -696,7 +704,7 @@ grpc_mdstr *grpc_mdstr_ref(grpc_mdstr *gs DEBUG_ARGS) {
   return gs;
 }
 
-void grpc_mdstr_unref(grpc_mdstr *gs DEBUG_ARGS) {
+void grpc_mdstr_unref(grpc_exec_ctx *exec_ctx, grpc_mdstr *gs DEBUG_ARGS) {
   internal_string *s = (internal_string *)gs;
   if (is_mdstr_static(gs)) return;
 #ifdef GRPC_METADATA_REFCOUNT_DEBUG
@@ -709,7 +717,7 @@ void grpc_mdstr_unref(grpc_mdstr *gs DEBUG_ARGS) {
         &g_strtab_shard[SHARD_IDX(s->hash, LOG2_STRTAB_SHARD_COUNT)];
     gpr_mu_lock(&shard->mu);
     GPR_ASSERT(0 == gpr_atm_no_barrier_load(&s->refcnt));
-    internal_destroy_string(shard, s);
+    internal_destroy_string(exec_ctx, shard, s);
     gpr_mu_unlock(&shard->mu);
   }
 }
diff --git a/src/core/lib/transport/metadata.h b/src/core/lib/transport/metadata.h
index a4955a1ea7..991eee96f1 100644
--- a/src/core/lib/transport/metadata.h
+++ b/src/core/lib/transport/metadata.h
@@ -37,6 +37,8 @@
 #include <grpc/slice.h>
 #include <grpc/support/useful.h>
 
+#include "src/core/lib/iomgr/exec_ctx.h"
+
 #ifdef __cplusplus
 extern "C" {
 #endif
@@ -96,7 +98,7 @@ void grpc_test_only_set_metadata_hash_seed(uint32_t seed);
    clients may have handy */
 grpc_mdstr *grpc_mdstr_from_string(const char *str);
 /* Unrefs the slice. */
-grpc_mdstr *grpc_mdstr_from_slice(grpc_slice slice);
+grpc_mdstr *grpc_mdstr_from_slice(grpc_exec_ctx *exec_ctx, grpc_slice slice);
 grpc_mdstr *grpc_mdstr_from_buffer(const uint8_t *str, size_t length);
 
 /* Returns a borrowed slice from the mdstr with its contents base64 encoded
@@ -105,12 +107,16 @@ grpc_slice grpc_mdstr_as_base64_encoded_and_huffman_compressed(grpc_mdstr *str);
 
 /* Constructors for grpc_mdelem instances; take a variety of data types that
    clients may have handy */
-grpc_mdelem *grpc_mdelem_from_metadata_strings(grpc_mdstr *key,
+grpc_mdelem *grpc_mdelem_from_metadata_strings(grpc_exec_ctx *exec_ctx,
+                                               grpc_mdstr *key,
                                                grpc_mdstr *value);
-grpc_mdelem *grpc_mdelem_from_strings(const char *key, const char *value);
+grpc_mdelem *grpc_mdelem_from_strings(grpc_exec_ctx *exec_ctx, const char *key,
+                                      const char *value);
 /* Unrefs the slices. */
-grpc_mdelem *grpc_mdelem_from_slices(grpc_slice key, grpc_slice value);
-grpc_mdelem *grpc_mdelem_from_string_and_buffer(const char *key,
+grpc_mdelem *grpc_mdelem_from_slices(grpc_exec_ctx *exec_ctx, grpc_slice key,
+                                     grpc_slice value);
+grpc_mdelem *grpc_mdelem_from_string_and_buffer(grpc_exec_ctx *exec_ctx,
+                                                const char *key,
                                                 const uint8_t *value,
                                                 size_t value_length);
 
@@ -127,22 +133,26 @@ void *grpc_mdelem_set_user_data(grpc_mdelem *md, void (*destroy_func)(void *),
 //#define GRPC_METADATA_REFCOUNT_DEBUG
 #ifdef GRPC_METADATA_REFCOUNT_DEBUG
 #define GRPC_MDSTR_REF(s) grpc_mdstr_ref((s), __FILE__, __LINE__)
-#define GRPC_MDSTR_UNREF(s) grpc_mdstr_unref((s), __FILE__, __LINE__)
+#define GRPC_MDSTR_UNREF(exec_ctx, s) \
+  grpc_mdstr_unref((exec_ctx), (s), __FILE__, __LINE__)
 #define GRPC_MDELEM_REF(s) grpc_mdelem_ref((s), __FILE__, __LINE__)
-#define GRPC_MDELEM_UNREF(s) grpc_mdelem_unref((s), __FILE__, __LINE__)
+#define GRPC_MDELEM_UNREF(exec_ctx, s) \
+  grpc_mdelem_unref((exec_ctx), (s), __FILE__, __LINE__)
 grpc_mdstr *grpc_mdstr_ref(grpc_mdstr *s, const char *file, int line);
-void grpc_mdstr_unref(grpc_mdstr *s, const char *file, int line);
+void grpc_mdstr_unref(grpc_exec_ctx *exec_ctx, grpc_mdstr *s, const char *file,
+                      int line);
 grpc_mdelem *grpc_mdelem_ref(grpc_mdelem *md, const char *file, int line);
-void grpc_mdelem_unref(grpc_mdelem *md, const char *file, int line);
+void grpc_mdelem_unref(grpc_exec_ctx *exec_ctx, grpc_mdelem *md,
+                       const char *file, int line);
 #else
 #define GRPC_MDSTR_REF(s) grpc_mdstr_ref((s))
-#define GRPC_MDSTR_UNREF(s) grpc_mdstr_unref((s))
+#define GRPC_MDSTR_UNREF(exec_ctx, s) grpc_mdstr_unref((exec_ctx), (s))
 #define GRPC_MDELEM_REF(s) grpc_mdelem_ref((s))
-#define GRPC_MDELEM_UNREF(s) grpc_mdelem_unref((s))
+#define GRPC_MDELEM_UNREF(exec_ctx, s) grpc_mdelem_unref((exec_ctx), (s))
 grpc_mdstr *grpc_mdstr_ref(grpc_mdstr *s);
-void grpc_mdstr_unref(grpc_mdstr *s);
+void grpc_mdstr_unref(grpc_exec_ctx *exec_ctx, grpc_mdstr *s);
 grpc_mdelem *grpc_mdelem_ref(grpc_mdelem *md);
-void grpc_mdelem_unref(grpc_mdelem *md);
+void grpc_mdelem_unref(grpc_exec_ctx *exec_ctx, grpc_mdelem *md);
 #endif
 
 /* Recover a char* from a grpc_mdstr. The returned string is null terminated.
@@ -162,7 +172,7 @@ int grpc_mdstr_is_bin_suffixed(grpc_mdstr *s);
 #define GRPC_MDSTR_KV_HASH(k_hash, v_hash) (GPR_ROTL((k_hash), 2) ^ (v_hash))
 
 void grpc_mdctx_global_init(void);
-void grpc_mdctx_global_shutdown(void);
+void grpc_mdctx_global_shutdown(grpc_exec_ctx *exec_ctx);
 
 /* Implementation provided by chttp2_transport */
 extern grpc_slice (*grpc_chttp2_base64_encode_and_huffman_compress)(
diff --git a/src/core/lib/transport/metadata_batch.c b/src/core/lib/transport/metadata_batch.c
index 84b5a74d51..b62ecc3aa6 100644
--- a/src/core/lib/transport/metadata_batch.c
+++ b/src/core/lib/transport/metadata_batch.c
@@ -72,10 +72,11 @@ void grpc_metadata_batch_init(grpc_metadata_batch *batch) {
   batch->deadline = gpr_inf_future(GPR_CLOCK_REALTIME);
 }
 
-void grpc_metadata_batch_destroy(grpc_metadata_batch *batch) {
+void grpc_metadata_batch_destroy(grpc_exec_ctx *exec_ctx,
+                                 grpc_metadata_batch *batch) {
   grpc_linked_mdelem *l;
   for (l = batch->list.head; l; l = l->next) {
-    GRPC_MDELEM_UNREF(l->md);
+    GRPC_MDELEM_UNREF(exec_ctx, l->md);
   }
 }
 
@@ -140,8 +141,10 @@ void grpc_metadata_batch_move(grpc_metadata_batch *dst,
   memset(src, 0, sizeof(grpc_metadata_batch));
 }
 
-void grpc_metadata_batch_filter(grpc_metadata_batch *batch,
-                                grpc_mdelem *(*filter)(void *user_data,
+void grpc_metadata_batch_filter(grpc_exec_ctx *exec_ctx,
+                                grpc_metadata_batch *batch,
+                                grpc_mdelem *(*filter)(grpc_exec_ctx *exec_ctx,
+                                                       void *user_data,
                                                        grpc_mdelem *elem),
                                 void *user_data) {
   grpc_linked_mdelem *l;
@@ -152,7 +155,7 @@ void grpc_metadata_batch_filter(grpc_metadata_batch *batch,
   assert_valid_list(&batch->list);
   for (l = batch->list.head; l; l = next) {
     grpc_mdelem *orig = l->md;
-    grpc_mdelem *filt = filter(user_data, orig);
+    grpc_mdelem *filt = filter(exec_ctx, user_data, orig);
     next = l->next;
     if (filt == NULL) {
       if (l->prev) {
@@ -168,9 +171,9 @@ void grpc_metadata_batch_filter(grpc_metadata_batch *batch,
         batch->list.tail = l->prev;
       }
       assert_valid_list(&batch->list);
-      GRPC_MDELEM_UNREF(l->md);
+      GRPC_MDELEM_UNREF(exec_ctx, l->md);
     } else if (filt != orig) {
-      GRPC_MDELEM_UNREF(orig);
+      GRPC_MDELEM_UNREF(exec_ctx, orig);
       l->md = filt;
     }
   }
@@ -179,13 +182,15 @@ void grpc_metadata_batch_filter(grpc_metadata_batch *batch,
   GPR_TIMER_END("grpc_metadata_batch_filter", 0);
 }
 
-static grpc_mdelem *no_metadata_for_you(void *user_data, grpc_mdelem *elem) {
+static grpc_mdelem *no_metadata_for_you(grpc_exec_ctx *exec_ctx,
+                                        void *user_data, grpc_mdelem *elem) {
   return NULL;
 }
 
-void grpc_metadata_batch_clear(grpc_metadata_batch *batch) {
+void grpc_metadata_batch_clear(grpc_exec_ctx *exec_ctx,
+                               grpc_metadata_batch *batch) {
   batch->deadline = gpr_inf_future(GPR_CLOCK_REALTIME);
-  grpc_metadata_batch_filter(batch, no_metadata_for_you, NULL);
+  grpc_metadata_batch_filter(exec_ctx, batch, no_metadata_for_you, NULL);
 }
 
 bool grpc_metadata_batch_is_empty(grpc_metadata_batch *batch) {
diff --git a/src/core/lib/transport/metadata_batch.h b/src/core/lib/transport/metadata_batch.h
index 7a9ccb4bc8..c0bd5174ab 100644
--- a/src/core/lib/transport/metadata_batch.h
+++ b/src/core/lib/transport/metadata_batch.h
@@ -68,8 +68,10 @@ typedef struct grpc_metadata_batch {
 } grpc_metadata_batch;
 
 void grpc_metadata_batch_init(grpc_metadata_batch *batch);
-void grpc_metadata_batch_destroy(grpc_metadata_batch *batch);
-void grpc_metadata_batch_clear(grpc_metadata_batch *batch);
+void grpc_metadata_batch_destroy(grpc_exec_ctx *exec_ctx,
+                                 grpc_metadata_batch *batch);
+void grpc_metadata_batch_clear(grpc_exec_ctx *exec_ctx,
+                               grpc_metadata_batch *batch);
 bool grpc_metadata_batch_is_empty(grpc_metadata_batch *batch);
 
 /* Returns the transport size of the batch. */
@@ -118,8 +120,10 @@ void grpc_metadata_batch_add_tail(grpc_metadata_batch *batch,
     The return value from \a filter will be substituted for the
     grpc_mdelem passed to \a filter. If \a filter returns NULL,
     the element will be moved to the garbage list. */
-void grpc_metadata_batch_filter(grpc_metadata_batch *batch,
-                                grpc_mdelem *(*filter)(void *user_data,
+void grpc_metadata_batch_filter(grpc_exec_ctx *exec_ctx,
+                                grpc_metadata_batch *batch,
+                                grpc_mdelem *(*filter)(grpc_exec_ctx *exec_ctx,
+                                                       void *user_data,
                                                        grpc_mdelem *elem),
                                 void *user_data);
 
diff --git a/src/core/lib/transport/method_config.c b/src/core/lib/transport/method_config.c
new file mode 100644
index 0000000000..25fb54b37d
--- /dev/null
+++ b/src/core/lib/transport/method_config.c
@@ -0,0 +1,347 @@
+//
+// Copyright 2015, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+//
+
+#include "src/core/lib/transport/method_config.h"
+
+#include <string.h>
+
+#include <grpc/impl/codegen/grpc_types.h>
+#include <grpc/support/alloc.h>
+#include <grpc/support/log.h>
+#include <grpc/support/string_util.h>
+#include <grpc/support/time.h>
+
+#include "src/core/lib/transport/mdstr_hash_table.h"
+#include "src/core/lib/transport/metadata.h"
+
+//
+// grpc_method_config
+//
+
+// bool vtable
+
+static void* bool_copy(void* valuep) {
+  bool value = *(bool*)valuep;
+  bool* new_value = gpr_malloc(sizeof(bool));
+  *new_value = value;
+  return new_value;
+}
+
+static int bool_cmp(void* v1, void* v2) {
+  bool b1 = *(bool*)v1;
+  bool b2 = *(bool*)v2;
+  if (!b1 && b2) return -1;
+  if (b1 && !b2) return 1;
+  return 0;
+}
+
+static void free_mem(grpc_exec_ctx* exec_ctx, void* p) { gpr_free(p); }
+
+static grpc_mdstr_hash_table_vtable bool_vtable = {free_mem, bool_copy,
+                                                   bool_cmp};
+
+// timespec vtable
+
+static void* timespec_copy(void* valuep) {
+  gpr_timespec value = *(gpr_timespec*)valuep;
+  gpr_timespec* new_value = gpr_malloc(sizeof(gpr_timespec));
+  *new_value = value;
+  return new_value;
+}
+
+static int timespec_cmp(void* v1, void* v2) {
+  return gpr_time_cmp(*(gpr_timespec*)v1, *(gpr_timespec*)v2);
+}
+
+static grpc_mdstr_hash_table_vtable timespec_vtable = {free_mem, timespec_copy,
+                                                       timespec_cmp};
+
+// int32 vtable
+
+static void* int32_copy(void* valuep) {
+  int32_t value = *(int32_t*)valuep;
+  int32_t* new_value = gpr_malloc(sizeof(int32_t));
+  *new_value = value;
+  return new_value;
+}
+
+static int int32_cmp(void* v1, void* v2) {
+  int32_t i1 = *(int32_t*)v1;
+  int32_t i2 = *(int32_t*)v2;
+  if (i1 < i2) return -1;
+  if (i1 > i2) return 1;
+  return 0;
+}
+
+static grpc_mdstr_hash_table_vtable int32_vtable = {free_mem, int32_copy,
+                                                    int32_cmp};
+
+// Hash table keys.
+#define GRPC_METHOD_CONFIG_WAIT_FOR_READY "grpc.wait_for_ready"  // bool
+#define GRPC_METHOD_CONFIG_TIMEOUT "grpc.timeout"                // gpr_timespec
+#define GRPC_METHOD_CONFIG_MAX_REQUEST_MESSAGE_BYTES \
+  "grpc.max_request_message_bytes"  // int32
+#define GRPC_METHOD_CONFIG_MAX_RESPONSE_MESSAGE_BYTES \
+  "grpc.max_response_message_bytes"  // int32
+
+struct grpc_method_config {
+  grpc_mdstr_hash_table* table;
+  grpc_mdstr* wait_for_ready_key;
+  grpc_mdstr* timeout_key;
+  grpc_mdstr* max_request_message_bytes_key;
+  grpc_mdstr* max_response_message_bytes_key;
+};
+
+grpc_method_config* grpc_method_config_create(
+    bool* wait_for_ready, gpr_timespec* timeout,
+    int32_t* max_request_message_bytes, int32_t* max_response_message_bytes) {
+  grpc_method_config* method_config = gpr_malloc(sizeof(grpc_method_config));
+  memset(method_config, 0, sizeof(grpc_method_config));
+  method_config->wait_for_ready_key =
+      grpc_mdstr_from_string(GRPC_METHOD_CONFIG_WAIT_FOR_READY);
+  method_config->timeout_key =
+      grpc_mdstr_from_string(GRPC_METHOD_CONFIG_TIMEOUT);
+  method_config->max_request_message_bytes_key =
+      grpc_mdstr_from_string(GRPC_METHOD_CONFIG_MAX_REQUEST_MESSAGE_BYTES);
+  method_config->max_response_message_bytes_key =
+      grpc_mdstr_from_string(GRPC_METHOD_CONFIG_MAX_RESPONSE_MESSAGE_BYTES);
+  grpc_mdstr_hash_table_entry entries[4];
+  size_t num_entries = 0;
+  if (wait_for_ready != NULL) {
+    entries[num_entries].key = method_config->wait_for_ready_key;
+    entries[num_entries].value = wait_for_ready;
+    entries[num_entries].vtable = &bool_vtable;
+    ++num_entries;
+  }
+  if (timeout != NULL) {
+    entries[num_entries].key = method_config->timeout_key;
+    entries[num_entries].value = timeout;
+    entries[num_entries].vtable = &timespec_vtable;
+    ++num_entries;
+  }
+  if (max_request_message_bytes != NULL) {
+    entries[num_entries].key = method_config->max_request_message_bytes_key;
+    entries[num_entries].value = max_request_message_bytes;
+    entries[num_entries].vtable = &int32_vtable;
+    ++num_entries;
+  }
+  if (max_response_message_bytes != NULL) {
+    entries[num_entries].key = method_config->max_response_message_bytes_key;
+    entries[num_entries].value = max_response_message_bytes;
+    entries[num_entries].vtable = &int32_vtable;
+    ++num_entries;
+  }
+  method_config->table = grpc_mdstr_hash_table_create(num_entries, entries);
+  return method_config;
+}
+
+grpc_method_config* grpc_method_config_ref(grpc_method_config* method_config) {
+  grpc_mdstr_hash_table_ref(method_config->table);
+  return method_config;
+}
+
+void grpc_method_config_unref(grpc_exec_ctx* exec_ctx,
+                              grpc_method_config* method_config) {
+  if (grpc_mdstr_hash_table_unref(exec_ctx, method_config->table)) {
+    GRPC_MDSTR_UNREF(exec_ctx, method_config->wait_for_ready_key);
+    GRPC_MDSTR_UNREF(exec_ctx, method_config->timeout_key);
+    GRPC_MDSTR_UNREF(exec_ctx, method_config->max_request_message_bytes_key);
+    GRPC_MDSTR_UNREF(exec_ctx, method_config->max_response_message_bytes_key);
+    gpr_free(method_config);
+  }
+}
+
+int grpc_method_config_cmp(const grpc_method_config* method_config1,
+                           const grpc_method_config* method_config2) {
+  return grpc_mdstr_hash_table_cmp(method_config1->table,
+                                   method_config2->table);
+}
+
+const bool* grpc_method_config_get_wait_for_ready(
+    const grpc_method_config* method_config) {
+  return grpc_mdstr_hash_table_get(method_config->table,
+                                   method_config->wait_for_ready_key);
+}
+
+const gpr_timespec* grpc_method_config_get_timeout(
+    const grpc_method_config* method_config) {
+  return grpc_mdstr_hash_table_get(method_config->table,
+                                   method_config->timeout_key);
+}
+
+const int32_t* grpc_method_config_get_max_request_message_bytes(
+    const grpc_method_config* method_config) {
+  return grpc_mdstr_hash_table_get(
+      method_config->table, method_config->max_request_message_bytes_key);
+}
+
+const int32_t* grpc_method_config_get_max_response_message_bytes(
+    const grpc_method_config* method_config) {
+  return grpc_mdstr_hash_table_get(
+      method_config->table, method_config->max_response_message_bytes_key);
+}
+
+//
+// grpc_method_config_table
+//
+
+static void method_config_unref(grpc_exec_ctx* exec_ctx, void* valuep) {
+  grpc_method_config_unref(exec_ctx, valuep);
+}
+
+static void* method_config_ref(void* valuep) {
+  return grpc_method_config_ref(valuep);
+}
+
+static int method_config_cmp(void* valuep1, void* valuep2) {
+  return grpc_method_config_cmp(valuep1, valuep2);
+}
+
+static const grpc_mdstr_hash_table_vtable method_config_table_vtable = {
+    method_config_unref, method_config_ref, method_config_cmp};
+
+grpc_method_config_table* grpc_method_config_table_create(
+    size_t num_entries, grpc_method_config_table_entry* entries) {
+  grpc_mdstr_hash_table_entry* hash_table_entries =
+      gpr_malloc(sizeof(grpc_mdstr_hash_table_entry) * num_entries);
+  for (size_t i = 0; i < num_entries; ++i) {
+    hash_table_entries[i].key = entries[i].method_name;
+    hash_table_entries[i].value = entries[i].method_config;
+    hash_table_entries[i].vtable = &method_config_table_vtable;
+  }
+  grpc_method_config_table* method_config_table =
+      grpc_mdstr_hash_table_create(num_entries, hash_table_entries);
+  gpr_free(hash_table_entries);
+  return method_config_table;
+}
+
+grpc_method_config_table* grpc_method_config_table_ref(
+    grpc_method_config_table* table) {
+  return grpc_mdstr_hash_table_ref(table);
+}
+
+void grpc_method_config_table_unref(grpc_exec_ctx* exec_ctx,
+                                    grpc_method_config_table* table) {
+  grpc_mdstr_hash_table_unref(exec_ctx, table);
+}
+
+int grpc_method_config_table_cmp(const grpc_method_config_table* table1,
+                                 const grpc_method_config_table* table2) {
+  return grpc_mdstr_hash_table_cmp(table1, table2);
+}
+
+void* grpc_method_config_table_get(grpc_exec_ctx* exec_ctx,
+                                   const grpc_mdstr_hash_table* table,
+                                   const grpc_mdstr* path) {
+  void* value = grpc_mdstr_hash_table_get(table, path);
+  // If we didn't find a match for the path, try looking for a wildcard
+  // entry (i.e., change "/service/method" to "/service/*").
+  if (value == NULL) {
+    const char* path_str = grpc_mdstr_as_c_string(path);
+    const char* sep = strrchr(path_str, '/') + 1;
+    const size_t len = (size_t)(sep - path_str);
+    char* buf = gpr_malloc(len + 2);  // '*' and NUL
+    memcpy(buf, path_str, len);
+    buf[len] = '*';
+    buf[len + 1] = '\0';
+    grpc_mdstr* wildcard_path = grpc_mdstr_from_string(buf);
+    gpr_free(buf);
+    value = grpc_mdstr_hash_table_get(table, wildcard_path);
+    GRPC_MDSTR_UNREF(exec_ctx, wildcard_path);
+  }
+  return value;
+}
+
+static void* copy_arg(void* p) { return grpc_method_config_table_ref(p); }
+
+static void destroy_arg(grpc_exec_ctx* exec_ctx, void* p) {
+  grpc_method_config_table_unref(exec_ctx, p);
+}
+
+static int cmp_arg(void* p1, void* p2) {
+  return grpc_method_config_table_cmp(p1, p2);
+}
+
+static grpc_arg_pointer_vtable arg_vtable = {copy_arg, destroy_arg, cmp_arg};
+
+grpc_arg grpc_method_config_table_create_channel_arg(
+    grpc_method_config_table* table) {
+  grpc_arg arg;
+  arg.type = GRPC_ARG_POINTER;
+  arg.key = GRPC_ARG_SERVICE_CONFIG;
+  arg.value.pointer.p = table;
+  arg.value.pointer.vtable = &arg_vtable;
+  return arg;
+}
+
+// State used by convert_entry() below.
+typedef struct conversion_state {
+  void* (*convert_value)(const grpc_method_config* method_config);
+  const grpc_mdstr_hash_table_vtable* vtable;
+  size_t num_entries;
+  grpc_mdstr_hash_table_entry* entries;
+} conversion_state;
+
+// A function to be passed to grpc_mdstr_hash_table_iterate() to create
+// a copy of the entries.
+static void convert_entry(const grpc_mdstr_hash_table_entry* entry,
+                          void* user_data) {
+  conversion_state* state = user_data;
+  state->entries[state->num_entries].key = GRPC_MDSTR_REF(entry->key);
+  state->entries[state->num_entries].value = state->convert_value(entry->value);
+  state->entries[state->num_entries].vtable = state->vtable;
+  ++state->num_entries;
+}
+
+grpc_mdstr_hash_table* grpc_method_config_table_convert(
+    grpc_exec_ctx* exec_ctx, const grpc_method_config_table* table,
+    void* (*convert_value)(const grpc_method_config* method_config),
+    const grpc_mdstr_hash_table_vtable* vtable) {
+  // Create an array of the entries in the table with converted values.
+  conversion_state state;
+  state.convert_value = convert_value;
+  state.vtable = vtable;
+  state.num_entries = 0;
+  state.entries = gpr_malloc(sizeof(grpc_mdstr_hash_table_entry) *
+                             grpc_mdstr_hash_table_num_entries(table));
+  grpc_mdstr_hash_table_iterate(table, convert_entry, &state);
+  // Create a new table based on the array we just constructed.
+  grpc_mdstr_hash_table* new_table =
+      grpc_mdstr_hash_table_create(state.num_entries, state.entries);
+  // Clean up the array.
+  for (size_t i = 0; i < state.num_entries; ++i) {
+    GRPC_MDSTR_UNREF(exec_ctx, state.entries[i].key);
+    vtable->destroy_value(exec_ctx, state.entries[i].value);
+  }
+  gpr_free(state.entries);
+  // Return the new table.
+  return new_table;
+}
diff --git a/src/core/lib/transport/method_config.h b/src/core/lib/transport/method_config.h
new file mode 100644
index 0000000000..d17a493fd4
--- /dev/null
+++ b/src/core/lib/transport/method_config.h
@@ -0,0 +1,139 @@
+//
+// Copyright 2016, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+//
+
+#ifndef GRPC_CORE_LIB_TRANSPORT_METHOD_CONFIG_H
+#define GRPC_CORE_LIB_TRANSPORT_METHOD_CONFIG_H
+
+#include <stdbool.h>
+
+#include <grpc/impl/codegen/gpr_types.h>
+#include <grpc/impl/codegen/grpc_types.h>
+
+#include "src/core/lib/transport/mdstr_hash_table.h"
+#include "src/core/lib/transport/metadata.h"
+
+/// Per-method configuration.
+typedef struct grpc_method_config grpc_method_config;
+
+/// Creates a grpc_method_config with the specified parameters.
+/// Any parameter may be NULL to indicate that the value is unset.
+///
+/// \a wait_for_ready indicates whether the client should wait until the
+/// request deadline for the channel to become ready, even if there is a
+/// temporary failure before the deadline while attempting to connect.
+///
+/// \a timeout indicates the timeout for calls.
+///
+/// \a max_request_message_bytes and \a max_response_message_bytes
+/// indicate the maximum sizes of the request (checked when sending) and
+/// response (checked when receiving) messages.
+grpc_method_config* grpc_method_config_create(
+    bool* wait_for_ready, gpr_timespec* timeout,
+    int32_t* max_request_message_bytes, int32_t* max_response_message_bytes);
+
+grpc_method_config* grpc_method_config_ref(grpc_method_config* method_config);
+void grpc_method_config_unref(grpc_exec_ctx* exec_ctx,
+                              grpc_method_config* method_config);
+
+/// Compares two grpc_method_configs.
+/// The sort order is stable but undefined.
+int grpc_method_config_cmp(const grpc_method_config* method_config1,
+                           const grpc_method_config* method_config2);
+
+/// These methods return NULL if the requested field is unset.
+/// The caller does NOT take ownership of the result.
+const bool* grpc_method_config_get_wait_for_ready(
+    const grpc_method_config* method_config);
+const gpr_timespec* grpc_method_config_get_timeout(
+    const grpc_method_config* method_config);
+const int32_t* grpc_method_config_get_max_request_message_bytes(
+    const grpc_method_config* method_config);
+const int32_t* grpc_method_config_get_max_response_message_bytes(
+    const grpc_method_config* method_config);
+
+/// A table of method configs.
+typedef grpc_mdstr_hash_table grpc_method_config_table;
+
+typedef struct grpc_method_config_table_entry {
+  /// The name is of one of the following forms:
+  ///   service/method -- specifies exact service and method name
+  ///   service/*      -- matches all methods for the specified service
+  grpc_mdstr* method_name;
+  grpc_method_config* method_config;
+} grpc_method_config_table_entry;
+
+/// Takes new references to all keys and values in \a entries.
+grpc_method_config_table* grpc_method_config_table_create(
+    size_t num_entries, grpc_method_config_table_entry* entries);
+
+grpc_method_config_table* grpc_method_config_table_ref(
+    grpc_method_config_table* table);
+void grpc_method_config_table_unref(grpc_exec_ctx* exec_ctx,
+                                    grpc_method_config_table* table);
+
+/// Compares two grpc_method_config_tables.
+/// The sort order is stable but undefined.
+int grpc_method_config_table_cmp(const grpc_method_config_table* table1,
+                                 const grpc_method_config_table* table2);
+
+/// Gets the method config for the specified \a path, which should be of
+/// the form "/service/method".
+/// Returns NULL if the method has no config.
+/// Caller does NOT own a reference to the result.
+///
+/// Note: This returns a void* instead of a grpc_method_config* so that
+/// it can also be used for tables constructed via
+/// grpc_method_config_table_convert().
+void* grpc_method_config_table_get(grpc_exec_ctx* exec_ctx,
+                                   const grpc_mdstr_hash_table* table,
+                                   const grpc_mdstr* path);
+
+/// Returns a channel arg containing \a table.
+grpc_arg grpc_method_config_table_create_channel_arg(
+    grpc_method_config_table* table);
+
+/// Generates a new table from \a table whose values are converted to a
+/// new form via the \a convert_value function.  The new table will use
+/// \a vtable for its values.
+///
+/// This is generally used to convert the table's value type from
+/// grpc_method_config to a simple struct containing only the parameters
+/// relevant to a particular filter, thus avoiding the need for a hash
+/// table lookup on the fast path.  In that scenario, \a convert_value
+/// will return a new instance of the struct containing the values from
+/// the grpc_method_config, and \a vtable provides the methods for
+/// operating on the struct type.
+grpc_mdstr_hash_table* grpc_method_config_table_convert(
+    grpc_exec_ctx* exec_ctx, const grpc_method_config_table* table,
+    void* (*convert_value)(const grpc_method_config* method_config),
+    const grpc_mdstr_hash_table_vtable* vtable);
+
+#endif /* GRPC_CORE_LIB_TRANSPORT_METHOD_CONFIG_H */
diff --git a/src/core/lib/transport/pid_controller.h b/src/core/lib/transport/pid_controller.h
index 1bf2fbc564..0a86521e90 100644
--- a/src/core/lib/transport/pid_controller.h
+++ b/src/core/lib/transport/pid_controller.h
@@ -74,4 +74,4 @@ double grpc_pid_controller_update(grpc_pid_controller *pid_controller,
 /** Returns the last control value calculated */
 double grpc_pid_controller_last(grpc_pid_controller *pid_controller);
 
-#endif
+#endif /* GRPC_CORE_LIB_TRANSPORT_PID_CONTROLLER_H */
diff --git a/src/core/lib/transport/service_config.c b/src/core/lib/transport/service_config.c
index 2e2b59e3f7..552d3ec856 100644
--- a/src/core/lib/transport/service_config.c
+++ b/src/core/lib/transport/service_config.c
@@ -146,7 +146,8 @@ static char* parse_json_method_name(grpc_json* json) {
 // each name found, incrementing \a idx for each entry added.
 // Returns false on error.
 static bool parse_json_method_config(
-    grpc_json* json, void* (*create_value)(const grpc_json* method_config_json),
+    grpc_exec_ctx* exec_ctx, grpc_json* json,
+    void* (*create_value)(const grpc_json* method_config_json),
     const grpc_mdstr_hash_table_vtable* vtable,
     grpc_mdstr_hash_table_entry* entries, size_t* idx) {
   // Construct value.
@@ -176,13 +177,13 @@ static bool parse_json_method_config(
   }
   success = true;
 done:
-  vtable->destroy_value(method_config);
+  vtable->destroy_value(exec_ctx, method_config);
   gpr_strvec_destroy(&paths);
   return success;
 }
 
 grpc_mdstr_hash_table* grpc_service_config_create_method_config_table(
-    const grpc_service_config* service_config,
+    grpc_exec_ctx* exec_ctx, const grpc_service_config* service_config,
     void* (*create_value)(const grpc_json* method_config_json),
     const grpc_mdstr_hash_table_vtable* vtable) {
   const grpc_json* json = service_config->json_tree;
@@ -205,8 +206,8 @@ grpc_mdstr_hash_table* grpc_service_config_create_method_config_table(
       size_t idx = 0;
       for (grpc_json* method = field->child; method != NULL;
            method = method->next) {
-        if (!parse_json_method_config(method, create_value, vtable, entries,
-                                      &idx)) {
+        if (!parse_json_method_config(exec_ctx, method, create_value, vtable,
+                                      entries, &idx)) {
           return NULL;
         }
       }
@@ -219,15 +220,16 @@ grpc_mdstr_hash_table* grpc_service_config_create_method_config_table(
     method_config_table = grpc_mdstr_hash_table_create(num_entries, entries);
     // Clean up.
     for (size_t i = 0; i < num_entries; ++i) {
-      GRPC_MDSTR_UNREF(entries[i].key);
-      vtable->destroy_value(entries[i].value);
+      GRPC_MDSTR_UNREF(exec_ctx, entries[i].key);
+      vtable->destroy_value(exec_ctx, entries[i].value);
     }
     gpr_free(entries);
   }
   return method_config_table;
 }
 
-void* grpc_method_config_table_get(const grpc_mdstr_hash_table* table,
+void* grpc_method_config_table_get(grpc_exec_ctx* exec_ctx,
+                                   const grpc_mdstr_hash_table* table,
                                    const grpc_mdstr* path) {
   void* value = grpc_mdstr_hash_table_get(table, path);
   // If we didn't find a match for the path, try looking for a wildcard
@@ -243,7 +245,7 @@ void* grpc_method_config_table_get(const grpc_mdstr_hash_table* table,
     grpc_mdstr* wildcard_path = grpc_mdstr_from_string(buf);
     gpr_free(buf);
     value = grpc_mdstr_hash_table_get(table, wildcard_path);
-    GRPC_MDSTR_UNREF(wildcard_path);
+    GRPC_MDSTR_UNREF(exec_ctx, wildcard_path);
   }
   return value;
 }
diff --git a/src/core/lib/transport/service_config.h b/src/core/lib/transport/service_config.h
index 2ffe475193..f0897170fa 100644
--- a/src/core/lib/transport/service_config.h
+++ b/src/core/lib/transport/service_config.h
@@ -54,7 +54,7 @@ const char* grpc_service_config_get_lb_policy_name(
 /// \a vtable provides methods used to manage the values.
 /// Returns NULL on error.
 grpc_mdstr_hash_table* grpc_service_config_create_method_config_table(
-    const grpc_service_config* service_config,
+    grpc_exec_ctx* exec_ctx, const grpc_service_config* service_config,
     void* (*create_value)(const grpc_json* method_config_json),
     const grpc_mdstr_hash_table_vtable* vtable);
 
@@ -64,7 +64,8 @@ grpc_mdstr_hash_table* grpc_service_config_create_method_config_table(
 /// the form "/service/method".
 /// Returns NULL if the method has no config.
 /// Caller does NOT own a reference to the result.
-void* grpc_method_config_table_get(const grpc_mdstr_hash_table* table,
+void* grpc_method_config_table_get(grpc_exec_ctx* exec_ctx,
+                                   const grpc_mdstr_hash_table* table,
                                    const grpc_mdstr* path);
 
 #endif /* GRPC_CORE_LIB_TRANSPORT_SERVICE_CONFIG_H */
diff --git a/src/core/lib/transport/transport.c b/src/core/lib/transport/transport.c
index 0d24062c1e..055edbb39f 100644
--- a/src/core/lib/transport/transport.c
+++ b/src/core/lib/transport/transport.c
@@ -40,6 +40,7 @@
 #include <grpc/support/log.h>
 #include <grpc/support/sync.h>
 
+#include "src/core/lib/slice/slice_internal.h"
 #include "src/core/lib/slice/slice_string_helpers.h"
 #include "src/core/lib/support/string.h"
 #include "src/core/lib/transport/transport_impl.h"
@@ -212,12 +213,12 @@ void grpc_transport_stream_op_add_cancellation(grpc_transport_stream_op *op,
 }
 
 void grpc_transport_stream_op_add_cancellation_with_message(
-    grpc_transport_stream_op *op, grpc_status_code status,
-    grpc_slice *optional_message) {
+    grpc_exec_ctx *exec_ctx, grpc_transport_stream_op *op,
+    grpc_status_code status, grpc_slice *optional_message) {
   GPR_ASSERT(status != GRPC_STATUS_OK);
   if (op->cancel_error != GRPC_ERROR_NONE) {
     if (optional_message) {
-      grpc_slice_unref(*optional_message);
+      grpc_slice_unref_internal(exec_ctx, *optional_message);
     }
     return;
   }
@@ -227,7 +228,7 @@ void grpc_transport_stream_op_add_cancellation_with_message(
     error = grpc_error_set_str(GRPC_ERROR_CREATE(msg),
                                GRPC_ERROR_STR_GRPC_MESSAGE, msg);
     gpr_free(msg);
-    grpc_slice_unref(*optional_message);
+    grpc_slice_unref_internal(exec_ctx, *optional_message);
   } else {
     error = GRPC_ERROR_CREATE("Call cancelled");
   }
@@ -235,14 +236,15 @@ void grpc_transport_stream_op_add_cancellation_with_message(
   add_error(op, &op->cancel_error, error);
 }
 
-void grpc_transport_stream_op_add_close(grpc_transport_stream_op *op,
+void grpc_transport_stream_op_add_close(grpc_exec_ctx *exec_ctx,
+                                        grpc_transport_stream_op *op,
                                         grpc_status_code status,
                                         grpc_slice *optional_message) {
   GPR_ASSERT(status != GRPC_STATUS_OK);
   if (op->cancel_error != GRPC_ERROR_NONE ||
       op->close_error != GRPC_ERROR_NONE) {
     if (optional_message) {
-      grpc_slice_unref(*optional_message);
+      grpc_slice_unref_internal(exec_ctx, *optional_message);
     }
     return;
   }
@@ -252,7 +254,7 @@ void grpc_transport_stream_op_add_close(grpc_transport_stream_op *op,
     error = grpc_error_set_str(GRPC_ERROR_CREATE(msg),
                                GRPC_ERROR_STR_GRPC_MESSAGE, msg);
     gpr_free(msg);
-    grpc_slice_unref(*optional_message);
+    grpc_slice_unref_internal(exec_ctx, *optional_message);
   } else {
     error = GRPC_ERROR_CREATE("Call force closed");
   }
diff --git a/src/core/lib/transport/transport.h b/src/core/lib/transport/transport.h
index 96c26749c8..d1281830aa 100644
--- a/src/core/lib/transport/transport.h
+++ b/src/core/lib/transport/transport.h
@@ -249,10 +249,11 @@ void grpc_transport_stream_op_add_cancellation(grpc_transport_stream_op *op,
                                                grpc_status_code status);
 
 void grpc_transport_stream_op_add_cancellation_with_message(
-    grpc_transport_stream_op *op, grpc_status_code status,
-    grpc_slice *optional_message);
+    grpc_exec_ctx *exec_ctx, grpc_transport_stream_op *op,
+    grpc_status_code status, grpc_slice *optional_message);
 
-void grpc_transport_stream_op_add_close(grpc_transport_stream_op *op,
+void grpc_transport_stream_op_add_close(grpc_exec_ctx *exec_ctx,
+                                        grpc_transport_stream_op *op,
                                         grpc_status_code status,
                                         grpc_slice *optional_message);
 
diff --git a/src/core/lib/tsi/README.md b/src/core/lib/tsi/README.md
new file mode 100644
index 0000000000..3ca3c1ef38
--- /dev/null
+++ b/src/core/lib/tsi/README.md
@@ -0,0 +1,2 @@
+# Transport Security Interface
+An abstraction library over crypto and auth modules (typically OpenSSL)
diff --git a/src/cpp/common/channel_arguments.cc b/src/cpp/common/channel_arguments.cc
index 0301b5b8ec..1fdd106130 100644
--- a/src/cpp/common/channel_arguments.cc
+++ b/src/cpp/common/channel_arguments.cc
@@ -38,8 +38,11 @@
 #include <grpc++/resource_quota.h>
 #include <grpc/impl/codegen/grpc_types.h>
 #include <grpc/support/log.h>
+extern "C" {
 #include "src/core/lib/channel/channel_args.h"
+#include "src/core/lib/iomgr/exec_ctx.h"
 #include "src/core/lib/iomgr/socket_mutator.h"
+}
 namespace grpc {
 
 ChannelArguments::ChannelArguments() {
@@ -94,13 +97,15 @@ void ChannelArguments::SetSocketMutator(grpc_socket_mutator* mutator) {
   }
   grpc_arg mutator_arg = grpc_socket_mutator_to_arg(mutator);
   bool replaced = false;
+  grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
   for (auto it = args_.begin(); it != args_.end(); ++it) {
     if (it->type == mutator_arg.type &&
         grpc::string(it->key) == grpc::string(mutator_arg.key)) {
-      it->value.pointer.vtable->destroy(it->value.pointer.p);
+      it->value.pointer.vtable->destroy(&exec_ctx, it->value.pointer.p);
       it->value.pointer = mutator_arg.value.pointer;
     }
   }
+  grpc_exec_ctx_finish(&exec_ctx);
   if (!replaced) {
     args_.push_back(mutator_arg);
   }
diff --git a/src/cpp/common/channel_filter.cc b/src/cpp/common/channel_filter.cc
index ad2c0f2295..c0dc9dd63e 100644
--- a/src/cpp/common/channel_filter.cc
+++ b/src/cpp/common/channel_filter.cc
@@ -40,11 +40,12 @@ namespace grpc {
 
 // MetadataBatch
 
-grpc_linked_mdelem *MetadataBatch::AddMetadata(const string &key,
+grpc_linked_mdelem *MetadataBatch::AddMetadata(grpc_exec_ctx *exec_ctx,
+                                               const string &key,
                                                const string &value) {
   grpc_linked_mdelem *storage = new grpc_linked_mdelem;
   memset(storage, 0, sizeof(grpc_linked_mdelem));
-  storage->md = grpc_mdelem_from_strings(key.c_str(), value.c_str());
+  storage->md = grpc_mdelem_from_strings(exec_ctx, key.c_str(), value.c_str());
   grpc_metadata_batch_link_head(batch_, storage);
   return storage;
 }
@@ -89,7 +90,8 @@ std::vector<FilterRecord> *channel_filters;
 
 namespace {
 
-bool MaybeAddFilter(grpc_channel_stack_builder *builder, void *arg) {
+bool MaybeAddFilter(grpc_exec_ctx *exec_ctx,
+                    grpc_channel_stack_builder *builder, void *arg) {
   const FilterRecord &filter = *(FilterRecord *)arg;
   if (filter.include_filter) {
     const grpc_channel_args *args =
diff --git a/src/cpp/common/channel_filter.h b/src/cpp/common/channel_filter.h
index c9f50df732..5de8f5e463 100644
--- a/src/cpp/common/channel_filter.h
+++ b/src/cpp/common/channel_filter.h
@@ -70,7 +70,8 @@ class MetadataBatch {
   /// Adds metadata and returns the newly allocated storage.
   /// The caller takes ownership of the result, which must exist for the
   /// lifetime of the gRPC call.
-  grpc_linked_mdelem *AddMetadata(const string &key, const string &value);
+  grpc_linked_mdelem *AddMetadata(grpc_exec_ctx *exec_ctx, const string &key,
+                                  const string &value);
 
   class const_iterator : public std::iterator<std::bidirectional_iterator_tag,
                                               const grpc_mdelem> {
diff --git a/src/node/interop/interop_client.js b/src/node/interop/interop_client.js
index 46ddecfb1f..75cfb41342 100644
--- a/src/node/interop/interop_client.js
+++ b/src/node/interop/interop_client.js
@@ -312,6 +312,9 @@ function customMetadata(client, done) {
     }
   };
   var streaming_arg = {
+    response_parameters: [
+     {size: 314159}
+    ],
     payload: {
       body: zeroBuffer(271828)
     }
diff --git a/src/php/bin/generate_proto_php.sh b/src/php/bin/generate_proto_php.sh
index c558bc5769..416fa9df97 100755
--- a/src/php/bin/generate_proto_php.sh
+++ b/src/php/bin/generate_proto_php.sh
@@ -39,10 +39,13 @@ protoc --proto_path=src/proto/math \
 
 # replace the Empty message with EmptyMessage
 # because Empty is a PHP reserved word
-sed -i 's/message Empty/message EmptyMessage/g' \
-    src/proto/grpc/testing/empty.proto
-sed -i 's/grpc\.testing\.Empty/grpc\.testing\.EmptyMessage/g' \
-    src/proto/grpc/testing/test.proto
+output_file=$(mktemp)
+sed 's/message Empty/message EmptyMessage/g' \
+  src/proto/grpc/testing/empty.proto > $output_file
+mv $output_file ./src/proto/grpc/testing/empty.proto
+sed 's/grpc\.testing\.Empty/grpc\.testing\.EmptyMessage/g' \
+  src/proto/grpc/testing/test.proto > $output_file
+mv $output_file ./src/proto/grpc/testing/test.proto
 
 protoc --proto_path=. \
        --php_out=src/php/tests/interop \
@@ -53,7 +56,10 @@ protoc --proto_path=. \
        src/proto/grpc/testing/test.proto
 
 # change it back
-sed -i 's/message EmptyMessage/message Empty/g' \
-    src/proto/grpc/testing/empty.proto
-sed -i 's/grpc\.testing\.EmptyMessage/grpc\.testing\.Empty/g' \
-    src/proto/grpc/testing/test.proto
+sed 's/message EmptyMessage/message Empty/g' \
+  src/proto/grpc/testing/empty.proto > $output_file
+mv $output_file ./src/proto/grpc/testing/empty.proto
+sed 's/grpc\.testing\.EmptyMessage/grpc\.testing\.Empty/g' \
+  src/proto/grpc/testing/test.proto > $output_file
+mv $output_file ./src/proto/grpc/testing/test.proto
+
diff --git a/src/php/ext/grpc/call.c b/src/php/ext/grpc/call.c
index 3a49ea8708..64b1137c2a 100644
--- a/src/php/ext/grpc/call.c
+++ b/src/php/ext/grpc/call.c
@@ -478,6 +478,7 @@ PHP_METHOD(Call, startBatch) {
                                    true);
       add_property_zval(result, "status", recv_status);
       PHP_GRPC_DELREF(recv_status);
+      PHP_GRPC_FREE_STD_ZVAL(recv_status);
       break;
     case GRPC_OP_RECV_CLOSE_ON_SERVER:
       add_property_bool(result, "cancelled", cancelled);
@@ -501,6 +502,7 @@ cleanup:
     }
     if (ops[i].op == GRPC_OP_RECV_MESSAGE) {
       grpc_byte_buffer_destroy(message);
+      PHP_GRPC_FREE_STD_ZVAL(message_str);
     }
   }
   RETURN_DESTROY_ZVAL(result);
diff --git a/src/php/ext/grpc/call_credentials.c b/src/php/ext/grpc/call_credentials.c
index 3aafc3a19b..043817facd 100644
--- a/src/php/ext/grpc/call_credentials.c
+++ b/src/php/ext/grpc/call_credentials.c
@@ -111,9 +111,7 @@ PHP_METHOD(CallCredentials, createComposite) {
   grpc_call_credentials *creds =
       grpc_composite_call_credentials_create(cred1->wrapped, cred2->wrapped,
                                              NULL);
-  zval *creds_object;
-  PHP_GRPC_MAKE_STD_ZVAL(creds_object);
-  creds_object = grpc_php_wrap_call_credentials(creds TSRMLS_CC);
+  zval *creds_object = grpc_php_wrap_call_credentials(creds TSRMLS_CC);
   RETURN_DESTROY_ZVAL(creds_object);
 }
 
@@ -155,9 +153,7 @@ PHP_METHOD(CallCredentials, createFromPlugin) {
 
   grpc_call_credentials *creds =
     grpc_metadata_credentials_create_from_plugin(plugin, NULL);
-  zval *creds_object;
-  PHP_GRPC_MAKE_STD_ZVAL(creds_object);
-  creds_object = grpc_php_wrap_call_credentials(creds TSRMLS_CC);
+  zval *creds_object = grpc_php_wrap_call_credentials(creds TSRMLS_CC);
   RETURN_DESTROY_ZVAL(creds_object);
 }
 
@@ -211,6 +207,8 @@ void plugin_destroy_state(void *ptr) {
   plugin_state *state = (plugin_state *)ptr;
   efree(state->fci);
   efree(state->fci_cache);
+  PHP_GRPC_FREE_STD_ZVAL(state->fci->params);
+  PHP_GRPC_FREE_STD_ZVAL(state->fci->retval);
   efree(state);
 }
 
diff --git a/src/php/ext/grpc/channel_credentials.c b/src/php/ext/grpc/channel_credentials.c
index a32c4a4ea2..36a8223b88 100644
--- a/src/php/ext/grpc/channel_credentials.c
+++ b/src/php/ext/grpc/channel_credentials.c
@@ -121,9 +121,7 @@ PHP_METHOD(ChannelCredentials, setDefaultRootsPem) {
  */
 PHP_METHOD(ChannelCredentials, createDefault) {
   grpc_channel_credentials *creds = grpc_google_default_credentials_create();
-  zval *creds_object;
-  PHP_GRPC_MAKE_STD_ZVAL(creds_object);
-  creds_object = grpc_php_wrap_channel_credentials(creds TSRMLS_CC);
+  zval *creds_object = grpc_php_wrap_channel_credentials(creds TSRMLS_CC);
   RETURN_DESTROY_ZVAL(creds_object);
 }
 
@@ -160,9 +158,7 @@ PHP_METHOD(ChannelCredentials, createSsl) {
   grpc_channel_credentials *creds = grpc_ssl_credentials_create(
       pem_root_certs,
       pem_key_cert_pair.private_key == NULL ? NULL : &pem_key_cert_pair, NULL);
-  zval *creds_object;
-  PHP_GRPC_MAKE_STD_ZVAL(creds_object);
-  creds_object = grpc_php_wrap_channel_credentials(creds TSRMLS_CC);
+  zval *creds_object = grpc_php_wrap_channel_credentials(creds TSRMLS_CC);
   RETURN_DESTROY_ZVAL(creds_object);
 }
 
@@ -191,9 +187,7 @@ PHP_METHOD(ChannelCredentials, createComposite) {
   grpc_channel_credentials *creds =
       grpc_composite_channel_credentials_create(cred1->wrapped, cred2->wrapped,
                                                 NULL);
-  zval *creds_object;
-  PHP_GRPC_MAKE_STD_ZVAL(creds_object);
-  creds_object = grpc_php_wrap_channel_credentials(creds TSRMLS_CC);
+  zval *creds_object = grpc_php_wrap_channel_credentials(creds TSRMLS_CC);
   RETURN_DESTROY_ZVAL(creds_object);
 }
 
diff --git a/src/php/ext/grpc/php7_wrapper.h b/src/php/ext/grpc/php7_wrapper.h
index 1d7824113f..72e982d6fc 100644
--- a/src/php/ext/grpc/php7_wrapper.h
+++ b/src/php/ext/grpc/php7_wrapper.h
@@ -50,8 +50,13 @@
 
 #define PHP_GRPC_RETURN_STRING(val, dup) RETURN_STRING(val, dup)
 #define PHP_GRPC_MAKE_STD_ZVAL(pzv) MAKE_STD_ZVAL(pzv)
+#define PHP_GRPC_FREE_STD_ZVAL(pzv)
 #define PHP_GRPC_DELREF(zv) Z_DELREF_P(zv)
 
+#define RETURN_DESTROY_ZVAL(val) \
+  RETURN_ZVAL(val, false /* Don't execute copy constructor */, \
+              true /* Dealloc original before returning */)
+
 #define PHP_GRPC_WRAP_OBJECT_START(name) \
   typedef struct name { \
     zend_object std;
@@ -144,8 +149,15 @@ static inline int php_grpc_zend_hash_find(HashTable *ht, char *key, int len,
 #define PHP_GRPC_RETURN_STRING(val, dup) RETURN_STRING(val)
 #define PHP_GRPC_MAKE_STD_ZVAL(pzv) \
   pzv = (zval *)emalloc(sizeof(zval));
+#define PHP_GRPC_FREE_STD_ZVAL(pzv) efree(pzv);
 #define PHP_GRPC_DELREF(zv)
 
+#define RETURN_DESTROY_ZVAL(val) \
+  RETVAL_ZVAL(val, false /* Don't execute copy constructor */, \
+              true /* Dealloc original before returning */); \
+  efree(val); \
+  return
+
 #define PHP_GRPC_WRAP_OBJECT_START(name) \
   typedef struct name {
 #define PHP_GRPC_WRAP_OBJECT_END(name) \
diff --git a/src/php/ext/grpc/php_grpc.h b/src/php/ext/grpc/php_grpc.h
index e57a06545e..13083b0bc7 100644
--- a/src/php/ext/grpc/php_grpc.h
+++ b/src/php/ext/grpc/php_grpc.h
@@ -61,10 +61,6 @@ extern zend_module_entry grpc_module_entry;
 
 #include "grpc/grpc.h"
 
-#define RETURN_DESTROY_ZVAL(val)                               \
-  RETURN_ZVAL(val, false /* Don't execute copy constructor */, \
-              true /* Dealloc original before returning */)
-
 /* These are all function declarations */
 /* Code that runs at module initialization */
 PHP_MINIT_FUNCTION(grpc);
diff --git a/src/php/ext/grpc/server_credentials.c b/src/php/ext/grpc/server_credentials.c
index 1610c8ebb0..3e39fee246 100644
--- a/src/php/ext/grpc/server_credentials.c
+++ b/src/php/ext/grpc/server_credentials.c
@@ -113,9 +113,7 @@ PHP_METHOD(ServerCredentials, createSsl) {
   grpc_server_credentials *creds = grpc_ssl_server_credentials_create_ex(
       pem_root_certs, &pem_key_cert_pair, 1,
       GRPC_SSL_DONT_REQUEST_CLIENT_CERTIFICATE, NULL);
-  zval *creds_object;
-  PHP_GRPC_MAKE_STD_ZVAL(creds_object);
-  creds_object = grpc_php_wrap_server_credentials(creds TSRMLS_CC);
+  zval *creds_object = grpc_php_wrap_server_credentials(creds TSRMLS_CC);
   RETURN_DESTROY_ZVAL(creds_object);
 }
 
diff --git a/src/php/ext/grpc/timeval.c b/src/php/ext/grpc/timeval.c
index 945231b47f..7ada915aad 100644
--- a/src/php/ext/grpc/timeval.c
+++ b/src/php/ext/grpc/timeval.c
@@ -115,11 +115,9 @@ PHP_METHOD(Timeval, add) {
   }
   wrapped_grpc_timeval *self = Z_WRAPPED_GRPC_TIMEVAL_P(getThis());
   wrapped_grpc_timeval *other = Z_WRAPPED_GRPC_TIMEVAL_P(other_obj);
-  zval *sum;
-  PHP_GRPC_MAKE_STD_ZVAL(sum);
-  sum =
-      grpc_php_wrap_timeval(gpr_time_add(self->wrapped, other->wrapped)
-                            TSRMLS_CC);
+  zval *sum =
+    grpc_php_wrap_timeval(gpr_time_add(self->wrapped, other->wrapped)
+                          TSRMLS_CC);
   RETURN_DESTROY_ZVAL(sum);
 }
 
@@ -141,11 +139,9 @@ PHP_METHOD(Timeval, subtract) {
   }
   wrapped_grpc_timeval *self = Z_WRAPPED_GRPC_TIMEVAL_P(getThis());
   wrapped_grpc_timeval *other = Z_WRAPPED_GRPC_TIMEVAL_P(other_obj);
-  zval *diff;
-  PHP_GRPC_MAKE_STD_ZVAL(diff);
-  diff =
-      grpc_php_wrap_timeval(gpr_time_sub(self->wrapped, other->wrapped)
-                            TSRMLS_CC);
+  zval *diff =
+    grpc_php_wrap_timeval(gpr_time_sub(self->wrapped, other->wrapped)
+                          TSRMLS_CC);
   RETURN_DESTROY_ZVAL(diff);
 }
 
@@ -206,9 +202,7 @@ PHP_METHOD(Timeval, similar) {
  * @return Timeval The current time
  */
 PHP_METHOD(Timeval, now) {
-  zval *now;
-  PHP_GRPC_MAKE_STD_ZVAL(now);
-  now = grpc_php_wrap_timeval(gpr_now(GPR_CLOCK_REALTIME) TSRMLS_CC);
+  zval *now = grpc_php_wrap_timeval(gpr_now(GPR_CLOCK_REALTIME) TSRMLS_CC);
   RETURN_DESTROY_ZVAL(now);
 }
 
@@ -217,13 +211,9 @@ PHP_METHOD(Timeval, now) {
  * @return Timeval Zero length time interval
  */
 PHP_METHOD(Timeval, zero) {
-  zval *grpc_php_timeval_zero;
-  PHP_GRPC_MAKE_STD_ZVAL(grpc_php_timeval_zero);
-  grpc_php_timeval_zero =
-      grpc_php_wrap_timeval(gpr_time_0(GPR_CLOCK_REALTIME) TSRMLS_CC);
-  RETURN_ZVAL(grpc_php_timeval_zero,
-              false, /* Copy original before returning? */
-              true /* Destroy original before returning */);
+  zval *grpc_php_timeval_zero =
+    grpc_php_wrap_timeval(gpr_time_0(GPR_CLOCK_REALTIME) TSRMLS_CC);
+  RETURN_DESTROY_ZVAL(grpc_php_timeval_zero);
 }
 
 /**
@@ -231,10 +221,8 @@ PHP_METHOD(Timeval, zero) {
  * @return Timeval Infinite future time value
  */
 PHP_METHOD(Timeval, infFuture) {
-  zval *grpc_php_timeval_inf_future;
-  PHP_GRPC_MAKE_STD_ZVAL(grpc_php_timeval_inf_future);
-  grpc_php_timeval_inf_future =
-      grpc_php_wrap_timeval(gpr_inf_future(GPR_CLOCK_REALTIME) TSRMLS_CC);
+  zval *grpc_php_timeval_inf_future =
+    grpc_php_wrap_timeval(gpr_inf_future(GPR_CLOCK_REALTIME) TSRMLS_CC);
   RETURN_DESTROY_ZVAL(grpc_php_timeval_inf_future);
 }
 
@@ -243,10 +231,8 @@ PHP_METHOD(Timeval, infFuture) {
  * @return Timeval Infinite past time value
  */
 PHP_METHOD(Timeval, infPast) {
-  zval *grpc_php_timeval_inf_past;
-  PHP_GRPC_MAKE_STD_ZVAL(grpc_php_timeval_inf_past);
-  grpc_php_timeval_inf_past =
-      grpc_php_wrap_timeval(gpr_inf_past(GPR_CLOCK_REALTIME) TSRMLS_CC);
+  zval *grpc_php_timeval_inf_past =
+    grpc_php_wrap_timeval(gpr_inf_past(GPR_CLOCK_REALTIME) TSRMLS_CC);
   RETURN_DESTROY_ZVAL(grpc_php_timeval_inf_past);
 }
 
diff --git a/src/php/lib/Grpc/AbstractCall.php b/src/php/lib/Grpc/AbstractCall.php
index c4d56790f7..9f0b02b8bb 100644
--- a/src/php/lib/Grpc/AbstractCall.php
+++ b/src/php/lib/Grpc/AbstractCall.php
@@ -62,7 +62,7 @@ abstract class AbstractCall
         Channel $channel,
         $method,
         $deserialize,
-        $options = []
+        array $options = []
     ) {
         if (array_key_exists('timeout', $options) &&
             is_numeric($timeout = $options['timeout'])
@@ -89,7 +89,7 @@ abstract class AbstractCall
     }
 
     /**
-     * @return mixed The metadata sent by the server.
+     * @return mixed The metadata sent by the server
      */
     public function getMetadata()
     {
@@ -97,7 +97,7 @@ abstract class AbstractCall
     }
 
     /**
-     * @return mixed The trailing metadata sent by the server.
+     * @return mixed The trailing metadata sent by the server
      */
     public function getTrailingMetadata()
     {
@@ -105,7 +105,7 @@ abstract class AbstractCall
     }
 
     /**
-     * @return string The URI of the endpoint.
+     * @return string The URI of the endpoint
      */
     public function getPeer()
     {
@@ -167,8 +167,7 @@ abstract class AbstractCall
     /**
      * Set the CallCredentials for the underlying Call.
      *
-     * @param CallCredentials $call_credentials The CallCredentials
-     *                                          object
+     * @param CallCredentials $call_credentials The CallCredentials object
      */
     public function setCallCredentials($call_credentials)
     {
diff --git a/src/php/lib/Grpc/BaseStub.php b/src/php/lib/Grpc/BaseStub.php
index d0baeae955..a9e77b9396 100644
--- a/src/php/lib/Grpc/BaseStub.php
+++ b/src/php/lib/Grpc/BaseStub.php
@@ -48,14 +48,14 @@ class BaseStub
     private $update_metadata;
 
     /**
-     * @param $hostname string
-     * @param $opts array
+     * @param string  $hostname
+     * @param array   $opts
      *  - 'update_metadata': (optional) a callback function which takes in a
      * metadata array, and returns an updated metadata array
      *  - 'grpc.primary_user_agent': (optional) a user-agent string
-     * @param $channel Channel An already created Channel object
+     * @param Channel $channel An already created Channel object (optional)
      */
-    public function __construct($hostname, $opts, $channel = null)
+    public function __construct($hostname, $opts, Channel $channel = null)
     {
         $ssl_roots = file_get_contents(
             dirname(__FILE__).'/../../../../etc/roots.pem');
@@ -98,7 +98,7 @@ class BaseStub
     }
 
     /**
-     * @return string The URI of the endpoint.
+     * @return string The URI of the endpoint
      */
     public function getTarget()
     {
@@ -106,7 +106,7 @@ class BaseStub
     }
 
     /**
-     * @param $try_to_connect bool
+     * @param bool $try_to_connect (optional)
      *
      * @return int The grpc connectivity state
      */
@@ -145,6 +145,12 @@ class BaseStub
         return $this->_checkConnectivityState($new_state);
     }
 
+    /**
+     * @param $new_state Connect state
+     *
+     * @return bool true if state is CHANNEL_READY
+     * @throw Exception if state is CHANNEL_FATAL_FAILURE
+     */
     private function _checkConnectivityState($new_state)
     {
         if ($new_state == \Grpc\CHANNEL_READY) {
@@ -167,6 +173,10 @@ class BaseStub
 
     /**
      * constructs the auth uri for the jwt.
+     *
+     * @param string $method The method string
+     *
+     * @return string The URL string
      */
     private function _get_jwt_aud_uri($method)
     {
@@ -191,7 +201,7 @@ class BaseStub
      *
      * @param array $metadata The metadata map
      *
-     * @return $metadata Validated and key-normalized metadata map
+     * @return array $metadata Validated and key-normalized metadata map
      * @throw InvalidArgumentException if key contains invalid characters
      */
     private function _validate_and_normalize_metadata($metadata)
@@ -220,14 +230,16 @@ class BaseStub
      * @param mixed    $argument    The argument to the method
      * @param callable $deserialize A function that deserializes the response
      * @param array    $metadata    A metadata map to send to the server
+     *                              (optional)
+     * @param array    $options     An array of options (optional)
      *
      * @return SimpleSurfaceActiveCall The active call object
      */
     public function _simpleRequest($method,
                                    $argument,
                                    $deserialize,
-                                   $metadata = [],
-                                   $options = [])
+                                   array $metadata = [],
+                                   array $options = [])
     {
         $call = new UnaryCall($this->channel,
                               $method,
@@ -251,17 +263,17 @@ class BaseStub
      * output.
      *
      * @param string   $method      The name of the method to call
-     * @param array    $arguments   An array or Traversable of arguments to stream to the
-     *                              server
      * @param callable $deserialize A function that deserializes the response
      * @param array    $metadata    A metadata map to send to the server
+     *                              (optional)
+     * @param array    $options     An array of options (optional)
      *
      * @return ClientStreamingSurfaceActiveCall The active call object
      */
     public function _clientStreamRequest($method,
-                                         callable $deserialize,
-                                         $metadata = [],
-                                         $options = [])
+                                         $deserialize,
+                                         array $metadata = [],
+                                         array $options = [])
     {
         $call = new ClientStreamingCall($this->channel,
                                         $method,
@@ -281,21 +293,23 @@ class BaseStub
     }
 
     /**
-     * Call a remote method that takes a single argument and returns a stream of
-     * responses.
+     * Call a remote method that takes a single argument and returns a stream
+     * of responses.
      *
      * @param string   $method      The name of the method to call
      * @param mixed    $argument    The argument to the method
      * @param callable $deserialize A function that deserializes the responses
      * @param array    $metadata    A metadata map to send to the server
+     *                              (optional)
+     * @param array    $options     An array of options (optional)
      *
      * @return ServerStreamingSurfaceActiveCall The active call object
      */
     public function _serverStreamRequest($method,
                                          $argument,
-                                         callable $deserialize,
-                                         $metadata = [],
-                                         $options = [])
+                                         $deserialize,
+                                         array $metadata = [],
+                                         array $options = [])
     {
         $call = new ServerStreamingCall($this->channel,
                                         $method,
@@ -320,13 +334,15 @@ class BaseStub
      * @param string   $method      The name of the method to call
      * @param callable $deserialize A function that deserializes the responses
      * @param array    $metadata    A metadata map to send to the server
+     *                              (optional)
+     * @param array    $options     An array of options (optional)
      *
      * @return BidiStreamingSurfaceActiveCall The active call object
      */
     public function _bidiRequest($method,
-                                 callable $deserialize,
-                                 $metadata = [],
-                                 $options = [])
+                                 $deserialize,
+                                 array $metadata = [],
+                                 array $options = [])
     {
         $call = new BidiStreamingCall($this->channel,
                                       $method,
diff --git a/src/php/lib/Grpc/BidiStreamingCall.php b/src/php/lib/Grpc/BidiStreamingCall.php
index f0e1e811de..b03bbd204f 100644
--- a/src/php/lib/Grpc/BidiStreamingCall.php
+++ b/src/php/lib/Grpc/BidiStreamingCall.php
@@ -35,8 +35,8 @@
 namespace Grpc;
 
 /**
- * Represents an active call that allows for sending and recieving messages in
- * streams in any order.
+ * Represents an active call that allows for sending and recieving messages
+ * in streams in any order.
  */
 class BidiStreamingCall extends AbstractCall
 {
@@ -44,6 +44,7 @@ class BidiStreamingCall extends AbstractCall
      * Start the call.
      *
      * @param array $metadata Metadata to send with the call, if applicable
+     *                        (optional)
      */
     public function start(array $metadata = [])
     {
@@ -76,10 +77,10 @@ class BidiStreamingCall extends AbstractCall
      * writesDone is called.
      *
      * @param ByteBuffer $data    The data to write
-     * @param array      $options an array of options, possible keys:
-     *                            'flags' => a number
+     * @param array      $options An array of options, possible keys:
+     *                            'flags' => a number (optional)
      */
-    public function write($data, $options = [])
+    public function write($data, array $options = [])
     {
         $message_array = ['message' => $this->serializeMessage($data)];
         if (array_key_exists('flags', $options)) {
@@ -103,8 +104,8 @@ class BidiStreamingCall extends AbstractCall
     /**
      * Wait for the server to send the status, and return it.
      *
-     * @return \stdClass The status object, with integer $code, string $details,
-     *                   and array $metadata members
+     * @return \stdClass The status object, with integer $code, string
+     *                   $details, and array $metadata members
      */
     public function getStatus()
     {
diff --git a/src/php/lib/Grpc/ClientStreamingCall.php b/src/php/lib/Grpc/ClientStreamingCall.php
index 20db809ea3..c542f08872 100644
--- a/src/php/lib/Grpc/ClientStreamingCall.php
+++ b/src/php/lib/Grpc/ClientStreamingCall.php
@@ -35,8 +35,8 @@
 namespace Grpc;
 
 /**
- * Represents an active call that sends a stream of messages and then gets a
- * single response.
+ * Represents an active call that sends a stream of messages and then gets
+ * a single response.
  */
 class ClientStreamingCall extends AbstractCall
 {
@@ -44,8 +44,9 @@ class ClientStreamingCall extends AbstractCall
      * Start the call.
      *
      * @param array $metadata Metadata to send with the call, if applicable
+     *                        (optional)
      */
-    public function start($metadata = [])
+    public function start(array $metadata = [])
     {
         $this->call->startBatch([
             OP_SEND_INITIAL_METADATA => $metadata,
@@ -57,8 +58,8 @@ class ClientStreamingCall extends AbstractCall
      * wait is called.
      *
      * @param ByteBuffer $data    The data to write
-     * @param array      $options an array of options, possible keys:
-     *                            'flags' => a number
+     * @param array      $options An array of options, possible keys:
+     *                            'flags' => a number (optional)
      */
     public function write($data, array $options = [])
     {
diff --git a/src/php/lib/Grpc/ServerStreamingCall.php b/src/php/lib/Grpc/ServerStreamingCall.php
index 5aeeafa94a..406512bf57 100644
--- a/src/php/lib/Grpc/ServerStreamingCall.php
+++ b/src/php/lib/Grpc/ServerStreamingCall.php
@@ -35,8 +35,8 @@
 namespace Grpc;
 
 /**
- * Represents an active call that sends a single message and then gets a stream
- * of responses.
+ * Represents an active call that sends a single message and then gets a
+ * stream of responses.
  */
 class ServerStreamingCall extends AbstractCall
 {
@@ -45,10 +45,11 @@ class ServerStreamingCall extends AbstractCall
      *
      * @param mixed $data     The data to send
      * @param array $metadata Metadata to send with the call, if applicable
-     * @param array $options  an array of options, possible keys:
-     *                        'flags' => a number
+     *                        (optional)
+     * @param array $options  An array of options, possible keys:
+     *                        'flags' => a number (optional)
      */
-    public function start($data, $metadata = [], $options = [])
+    public function start($data, array $metadata = [], array $options = [])
     {
         $message_array = ['message' => $this->serializeMessage($data)];
         if (array_key_exists('flags', $options)) {
@@ -82,8 +83,8 @@ class ServerStreamingCall extends AbstractCall
     /**
      * Wait for the server to send the status, and return it.
      *
-     * @return \stdClass The status object, with integer $code, string $details,
-     *                   and array $metadata members
+     * @return \stdClass The status object, with integer $code, string
+     *                   $details, and array $metadata members
      */
     public function getStatus()
     {
diff --git a/src/php/lib/Grpc/UnaryCall.php b/src/php/lib/Grpc/UnaryCall.php
index e8eb6487a8..3c1cb158ea 100644
--- a/src/php/lib/Grpc/UnaryCall.php
+++ b/src/php/lib/Grpc/UnaryCall.php
@@ -35,8 +35,8 @@
 namespace Grpc;
 
 /**
- * Represents an active call that sends a single message and then gets a single
- * response.
+ * Represents an active call that sends a single message and then gets a
+ * single response.
  */
 class UnaryCall extends AbstractCall
 {
@@ -45,10 +45,11 @@ class UnaryCall extends AbstractCall
      *
      * @param mixed $data     The data to send
      * @param array $metadata Metadata to send with the call, if applicable
-     * @param array $options  an array of options, possible keys:
-     *                        'flags' => a number
+     *                        (optional)
+     * @param array $options  An array of options, possible keys:
+     *                        'flags' => a number (optional)
      */
-    public function start($data, $metadata = [], $options = [])
+    public function start($data, array $metadata = [], array $options = [])
     {
         $message_array = ['message' => $this->serializeMessage($data)];
         if (isset($options['flags'])) {
diff --git a/src/php/tests/interop/interop_client.php b/src/php/tests/interop/interop_client.php
index d201915d66..2acf5612c7 100755
--- a/src/php/tests/interop/interop_client.php
+++ b/src/php/tests/interop/interop_client.php
@@ -451,11 +451,22 @@ function customMetadata($stub)
 
     $streaming_request = new grpc\testing\StreamingOutputCallRequest();
     $streaming_request->setPayload($payload);
+    $response_parameters = new grpc\testing\ResponseParameters();
+    $response_parameters->setSize($response_len);
+    $streaming_request->getResponseParameters()[] = $response_parameters;
     $streaming_call->write($streaming_request);
     $streaming_call->writesDone();
+    $result = $streaming_call->read();
 
     hardAssertIfStatusOk($streaming_call->getStatus());
 
+    $streaming_initial_metadata = $streaming_call->getMetadata();
+    hardAssert(array_key_exists($ECHO_INITIAL_KEY, $streaming_initial_metadata),
+               'Initial metadata does not contain expected key');
+    hardAssert(
+        $streaming_initial_metadata[$ECHO_INITIAL_KEY][0] === $ECHO_INITIAL_VALUE,
+        'Incorrect initial metadata value');
+
     $streaming_trailing_metadata = $streaming_call->getTrailingMetadata();
     hardAssert(array_key_exists($ECHO_TRAILING_KEY,
                                 $streaming_trailing_metadata),
diff --git a/src/proto/grpc/testing/BUILD b/src/proto/grpc/testing/BUILD
new file mode 100644
index 0000000000..f9f9cbceaf
--- /dev/null
+++ b/src/proto/grpc/testing/BUILD
@@ -0,0 +1,63 @@
+
+package(default_visibility = ["//visibility:public"])
+
+load("//bazel:grpc_build_system.bzl", "grpc_proto_library")
+
+grpc_proto_library(
+    name = "compiler_test_proto",
+    srcs = ["compiler_test.proto"],
+)
+
+grpc_proto_library(
+    name = "control_proto",
+    srcs = ["control.proto"],
+    deps = ["payloads_proto", "stats_proto"],
+)
+
+grpc_proto_library(
+    name = "echo_messages_proto",
+    srcs = ["echo_messages.proto"],
+)
+
+grpc_proto_library(
+    name = "echo_proto",
+    srcs = ["echo.proto"],
+    deps = ["echo_messages_proto"],
+)
+
+grpc_proto_library(
+    name = "empty_proto",
+    srcs = ["empty.proto"],
+)
+
+grpc_proto_library(
+    name = "messages_proto",
+    srcs = ["messages.proto"],
+)
+
+grpc_proto_library(
+    name = "metrics_proto",
+    srcs = ["metrics.proto"],
+)
+
+grpc_proto_library(
+    name = "payloads_proto",
+    srcs = ["payloads.proto"],
+)
+
+grpc_proto_library(
+    name = "services_proto",
+    srcs = ["services.proto"],
+    deps = ["control_proto", "messages_proto"],
+)
+
+grpc_proto_library(
+    name = "stats_proto",
+    srcs = ["stats.proto"],
+)
+
+grpc_proto_library(
+    name = "test_proto",
+    srcs = ["test.proto"],
+    deps = ["empty_proto", "messages_proto"],
+)
diff --git a/src/proto/grpc/testing/control.proto b/src/proto/grpc/testing/control.proto
index be387cf786..529313cfb1 100644
--- a/src/proto/grpc/testing/control.proto
+++ b/src/proto/grpc/testing/control.proto
@@ -78,6 +78,14 @@ message SecurityParams {
   string server_host_override = 2;
 }
 
+message ChannelArg {
+  string name = 1;
+  oneof value {
+    string str_value = 2;
+    int32 int_value = 3;
+  }
+}
+
 message ClientConfig {
   // List of targets to connect to. At least one target needs to be specified.
   repeated string server_targets = 1;
@@ -103,6 +111,8 @@ message ClientConfig {
 
   // If we use an OTHER_CLIENT client_type, this string gives more detail
   string other_client_api = 15;
+
+  repeated ChannelArg channel_args = 16;
 }
 
 message ClientStatus { ClientStats stats = 1; }
diff --git a/src/proto/grpc/testing/duplicate/BUILD b/src/proto/grpc/testing/duplicate/BUILD
new file mode 100644
index 0000000000..255e699bec
--- /dev/null
+++ b/src/proto/grpc/testing/duplicate/BUILD
@@ -0,0 +1,10 @@
+
+package(default_visibility = ["//visibility:public"])
+
+load("//bazel:grpc_build_system.bzl", "grpc_proto_library")
+
+grpc_proto_library(
+    name = "echo_duplicate_proto",
+    srcs = ["echo_duplicate.proto"],
+    deps = ["//src/proto/grpc/testing:echo_messages_proto"],
+)
diff --git a/src/python/grpcio/commands.py b/src/python/grpcio/commands.py
index ea3b6f3391..701c6af017 100644
--- a/src/python/grpcio/commands.py
+++ b/src/python/grpcio/commands.py
@@ -62,6 +62,7 @@ napoleon_numpy_docstring = True
 napoleon_include_special_with_doc = True
 
 html_theme = 'sphinx_rtd_theme'
+copyright = "2016, The gRPC Authors"
 """
 
 API_GLOSSARY = """
diff --git a/src/python/grpcio/grpc/_channel.py b/src/python/grpcio/grpc/_channel.py
index 41e9163cd6..e8c6a99cb1 100644
--- a/src/python/grpcio/grpc/_channel.py
+++ b/src/python/grpcio/grpc/_channel.py
@@ -32,6 +32,7 @@
 import sys
 import threading
 import time
+import logging
 
 import grpc
 from grpc import _common
@@ -197,7 +198,16 @@ def _consume_request_iterator(
   event_handler = _event_handler(state, call, None)
 
   def consume_request_iterator():
-    for request in request_iterator:
+    while True:
+      try:
+        request = next(request_iterator)
+      except StopIteration:
+        break
+      except Exception as e:
+        logging.exception("Exception iterating requests!")
+        call.cancel()
+        _abort(state, grpc.StatusCode.UNKNOWN, "Exception iterating requests!")
+        return
       serialized_request = _common.serialize(request, request_serializer)
       with state.condition:
         if state.code is None and not state.cancelled:
diff --git a/src/python/grpcio/grpc_core_dependencies.py b/src/python/grpcio/grpc_core_dependencies.py
index 81ff1abce6..f58dd8ea40 100644
--- a/src/python/grpcio/grpc_core_dependencies.py
+++ b/src/python/grpcio/grpc_core_dependencies.py
@@ -82,6 +82,8 @@ CORE_SOURCE_FILES = [
   'src/core/lib/channel/connected_channel.c',
   'src/core/lib/channel/deadline_filter.c',
   'src/core/lib/channel/handshaker.c',
+  'src/core/lib/channel/handshaker_factory.c',
+  'src/core/lib/channel/handshaker_registry.c',
   'src/core/lib/channel/http_client_filter.c',
   'src/core/lib/channel/http_server_filter.c',
   'src/core/lib/channel/message_size_filter.c',
diff --git a/src/python/grpcio_tests/tests/interop/_insecure_interop_test.py b/src/python/grpcio_tests/tests/interop/_insecure_intraop_test.py
index 936c895bd2..4fb22b4d9d 100644
--- a/src/python/grpcio_tests/tests/interop/_insecure_interop_test.py
+++ b/src/python/grpcio_tests/tests/interop/_insecure_intraop_test.py
@@ -35,13 +35,13 @@ import unittest
 import grpc
 from src.proto.grpc.testing import test_pb2
 
-from tests.interop import _interop_test_case
+from tests.interop import _intraop_test_case
 from tests.interop import methods
 from tests.interop import server
 
 
-class InsecureInteropTest(
-    _interop_test_case.InteropTestCase,
+class InsecureIntraopTest(
+    _intraop_test_case.IntraopTestCase,
     unittest.TestCase):
 
   def setUp(self):
diff --git a/src/python/grpcio_tests/tests/interop/_interop_test_case.py b/src/python/grpcio_tests/tests/interop/_intraop_test_case.py
index ccea17a66d..fe1c173992 100644
--- a/src/python/grpcio_tests/tests/interop/_interop_test_case.py
+++ b/src/python/grpcio_tests/tests/interop/_intraop_test_case.py
@@ -32,7 +32,7 @@
 from tests.interop import methods
 
 
-class InteropTestCase(object):
+class IntraopTestCase(object):
   """Unit test methods.
 
   This class must be mixed in with unittest.TestCase and a class that defines
diff --git a/src/python/grpcio_tests/tests/interop/_secure_interop_test.py b/src/python/grpcio_tests/tests/interop/_secure_intraop_test.py
index eaca553e1b..3665c69726 100644
--- a/src/python/grpcio_tests/tests/interop/_secure_interop_test.py
+++ b/src/python/grpcio_tests/tests/interop/_secure_intraop_test.py
@@ -35,15 +35,15 @@ import unittest
 import grpc
 from src.proto.grpc.testing import test_pb2
 
-from tests.interop import _interop_test_case
+from tests.interop import _intraop_test_case
 from tests.interop import methods
 from tests.interop import resources
 
 _SERVER_HOST_OVERRIDE = 'foo.test.google.fr'
 
 
-class SecureInteropTest(
-    _interop_test_case.InteropTestCase,
+class SecureIntraopTest(
+    _intraop_test_case.IntraopTestCase,
     unittest.TestCase):
 
   def setUp(self):
diff --git a/src/python/grpcio_tests/tests/qps/benchmark_client.py b/src/python/grpcio_tests/tests/qps/benchmark_client.py
index 83b46c914e..650e4756e7 100644
--- a/src/python/grpcio_tests/tests/qps/benchmark_client.py
+++ b/src/python/grpcio_tests/tests/qps/benchmark_client.py
@@ -68,12 +68,8 @@ class BenchmarkClient:
     else:
       channel = grpc.insecure_channel(server)
 
-    connected_event = threading.Event()
-    def wait_for_ready(connectivity):
-      if connectivity == grpc.ChannelConnectivity.READY:
-        connected_event.set()
-    channel.subscribe(wait_for_ready, try_to_connect=True)
-    connected_event.wait()
+    # waits for the channel to be ready before we start sending messages
+    grpc.channel_ready_future(channel).result()
 
     if config.payload_config.WhichOneof('payload') == 'simple_params':
       self._generic = False
diff --git a/src/python/grpcio_tests/tests/reflection/_reflection_servicer_test.py b/src/python/grpcio_tests/tests/reflection/_reflection_servicer_test.py
index c7bfeaeb95..43d6c971b5 100644
--- a/src/python/grpcio_tests/tests/reflection/_reflection_servicer_test.py
+++ b/src/python/grpcio_tests/tests/reflection/_reflection_servicer_test.py
@@ -75,7 +75,7 @@ class ReflectionServicerTest(unittest.TestCase):
         file_by_filename='i-donut-exist'
       ),
     )
-    responses = tuple(self._stub.ServerReflectionInfo(requests))
+    responses = tuple(self._stub.ServerReflectionInfo(iter(requests)))
     expected_responses = (
       reflection_pb2.ServerReflectionResponse(
         valid_host='',
@@ -93,7 +93,7 @@ class ReflectionServicerTest(unittest.TestCase):
         )
       ),
     )
-    self.assertEqual(expected_responses, responses)
+    self.assertSequenceEqual(expected_responses, responses)
 
   def testFileBySymbol(self):
     requests = (
@@ -104,7 +104,7 @@ class ReflectionServicerTest(unittest.TestCase):
         file_containing_symbol='i.donut.exist.co.uk.org.net.me.name.foo'
       ),
     )
-    responses = tuple(self._stub.ServerReflectionInfo(requests))
+    responses = tuple(self._stub.ServerReflectionInfo(iter(requests)))
     expected_responses = (
       reflection_pb2.ServerReflectionResponse(
         valid_host='',
@@ -122,7 +122,7 @@ class ReflectionServicerTest(unittest.TestCase):
         )
       ),
     )
-    self.assertEqual(expected_responses, responses)
+    self.assertSequenceEqual(expected_responses, responses)
 
   @unittest.skip('TODO(atash): implement file-containing-extension reflection '
                  '(see https://github.com/google/protobuf/issues/2248)')
@@ -141,7 +141,7 @@ class ReflectionServicerTest(unittest.TestCase):
         ),
       ),
     )
-    responses = tuple(self._stub.ServerReflectionInfo(requests))
+    responses = tuple(self._stub.ServerReflectionInfo(iter(requests)))
     expected_responses = (
       reflection_pb2.ServerReflectionResponse(
         valid_host='',
@@ -159,7 +159,7 @@ class ReflectionServicerTest(unittest.TestCase):
         )
       ),
     )
-    self.assertEqual(expected_responses, responses)
+    self.assertSequenceEqual(expected_responses, responses)
 
   def testListServices(self):
     requests = (
@@ -167,7 +167,7 @@ class ReflectionServicerTest(unittest.TestCase):
         list_services='',
       ),
     )
-    responses = tuple(self._stub.ServerReflectionInfo(requests))
+    responses = tuple(self._stub.ServerReflectionInfo(iter(requests)))
     expected_responses = (
       reflection_pb2.ServerReflectionResponse(
         valid_host='',
@@ -179,7 +179,7 @@ class ReflectionServicerTest(unittest.TestCase):
         )
       ),
     )
-    self.assertEqual(expected_responses, responses)
+    self.assertSequenceEqual(expected_responses, responses)
 
 if __name__ == '__main__':
   unittest.main(verbosity=2)
diff --git a/src/python/grpcio_tests/tests/stress/client.py b/src/python/grpcio_tests/tests/stress/client.py
index 390ea13021..b8116729b5 100644
--- a/src/python/grpcio_tests/tests/stress/client.py
+++ b/src/python/grpcio_tests/tests/stress/client.py
@@ -110,10 +110,13 @@ def _get_channel(target, args):
     channel_credentials = grpc.ssl_channel_credentials(
         root_certificates=root_certificates)
     options = (('grpc.ssl_target_name_override', args.server_host_override,),)
-    return grpc.secure_channel(
-        target, channel_credentials, options=options)
+    channel = grpc.secure_channel(target, channel_credentials, options=options)
   else:
-    return grpc.insecure_channel(target)
+    channel = grpc.insecure_channel(target)
+
+  # waits for the channel to be ready before we start sending messages
+  grpc.channel_ready_future(channel).result()
+  return channel
 
 def run_test(args):
   test_cases = _parse_weighted_test_cases(args.test_cases)
diff --git a/src/python/grpcio_tests/tests/tests.json b/src/python/grpcio_tests/tests/tests.json
index c31a5f9d33..70d965d3ca 100644
--- a/src/python/grpcio_tests/tests/tests.json
+++ b/src/python/grpcio_tests/tests/tests.json
@@ -1,7 +1,7 @@
 [
   "health_check._health_servicer_test.HealthServicerTest",
-  "interop._insecure_interop_test.InsecureInteropTest",
-  "interop._secure_interop_test.SecureInteropTest",
+  "interop._insecure_intraop_test.InsecureIntraopTest",
+  "interop._secure_intraop_test.SecureIntraopTest",
   "protoc_plugin._python_plugin_test.PythonPluginTest",
   "protoc_plugin._split_definitions_test.SameCommonTest",
   "protoc_plugin._split_definitions_test.SameSeparateTest",
@@ -28,6 +28,7 @@
   "unit._empty_message_test.EmptyMessageTest",
   "unit._exit_test.ExitTest",
   "unit._invalid_metadata_test.InvalidMetadataTest",
+  "unit._invocation_defects_test.InvocationDefectsTest",
   "unit._metadata_code_details_test.MetadataCodeDetailsTest",
   "unit._metadata_test.MetadataTest",
   "unit._rpc_test.RPCTest",
diff --git a/src/python/grpcio_tests/tests/unit/_compression_test.py b/src/python/grpcio_tests/tests/unit/_compression_test.py
index 83b9109466..4d3f02e917 100644
--- a/src/python/grpcio_tests/tests/unit/_compression_test.py
+++ b/src/python/grpcio_tests/tests/unit/_compression_test.py
@@ -125,7 +125,7 @@ class CompressionTest(unittest.TestCase):
     compressed_channel = grpc.insecure_channel('localhost:%d' % self._port,
         options=[('grpc.default_compression_algorithm', 1)])
     multi_callable = compressed_channel.stream_stream(_STREAM_STREAM)
-    call = multi_callable([request] * test_constants.STREAM_LENGTH)
+    call = multi_callable(iter([request] * test_constants.STREAM_LENGTH))
     for response in call:
       self.assertEqual(request, response)
 
diff --git a/src/python/grpcio_tests/tests/unit/_empty_message_test.py b/src/python/grpcio_tests/tests/unit/_empty_message_test.py
index 131f6e9452..69f4689279 100644
--- a/src/python/grpcio_tests/tests/unit/_empty_message_test.py
+++ b/src/python/grpcio_tests/tests/unit/_empty_message_test.py
@@ -123,12 +123,12 @@ class EmptyMessageTest(unittest.TestCase):
 
   def testStreamUnary(self):
     response = self._channel.stream_unary(_STREAM_UNARY)(
-        [_REQUEST] * test_constants.STREAM_LENGTH)
+        iter([_REQUEST] * test_constants.STREAM_LENGTH))
     self.assertEqual(_RESPONSE, response)
 
   def testStreamStream(self):
     response_iterator = self._channel.stream_stream(_STREAM_STREAM)(
-        [_REQUEST] * test_constants.STREAM_LENGTH)
+        iter([_REQUEST] * test_constants.STREAM_LENGTH))
     self.assertSequenceEqual(
         [_RESPONSE] * test_constants.STREAM_LENGTH, list(response_iterator))
 
diff --git a/src/python/grpcio_tests/tests/unit/_exit_scenarios.py b/src/python/grpcio_tests/tests/unit/_exit_scenarios.py
index b33802bf57..777527137f 100644
--- a/src/python/grpcio_tests/tests/unit/_exit_scenarios.py
+++ b/src/python/grpcio_tests/tests/unit/_exit_scenarios.py
@@ -240,7 +240,7 @@ if __name__ == '__main__':
       multi_callable = channel.stream_unary(method)
       future = multi_callable.future(infinite_request_iterator())
       result, call = multi_callable.with_call(
-          [REQUEST] * test_constants.STREAM_LENGTH)
+          iter([REQUEST] * test_constants.STREAM_LENGTH))
     elif (args.scenario == IN_FLIGHT_STREAM_STREAM_CALL or
           args.scenario == IN_FLIGHT_PARTIAL_STREAM_STREAM_CALL):
       multi_callable = channel.stream_stream(method)
diff --git a/src/python/grpcio_tests/tests/unit/_invocation_defects_test.py b/src/python/grpcio_tests/tests/unit/_invocation_defects_test.py
new file mode 100644
index 0000000000..4312679bb9
--- /dev/null
+++ b/src/python/grpcio_tests/tests/unit/_invocation_defects_test.py
@@ -0,0 +1,247 @@
+# Copyright 2016, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+import itertools
+import threading
+import unittest
+from concurrent import futures
+
+import grpc
+from grpc.framework.foundation import logging_pool
+
+from tests.unit.framework.common import test_constants
+from tests.unit.framework.common import test_control
+
+_SERIALIZE_REQUEST = lambda bytestring: bytestring * 2
+_DESERIALIZE_REQUEST = lambda bytestring: bytestring[len(bytestring) // 2:]
+_SERIALIZE_RESPONSE = lambda bytestring: bytestring * 3
+_DESERIALIZE_RESPONSE = lambda bytestring: bytestring[:len(bytestring) // 3]
+
+_UNARY_UNARY = '/test/UnaryUnary'
+_UNARY_STREAM = '/test/UnaryStream'
+_STREAM_UNARY = '/test/StreamUnary'
+_STREAM_STREAM = '/test/StreamStream'
+
+
+class _Callback(object):
+  def __init__(self):
+    self._condition = threading.Condition()
+    self._value = None
+    self._called = False
+
+  def __call__(self, value):
+    with self._condition:
+      self._value = value
+      self._called = True
+      self._condition.notify_all()
+
+  def value(self):
+    with self._condition:
+      while not self._called:
+        self._condition.wait()
+      return self._value
+
+
+class _Handler(object):
+  def __init__(self, control):
+    self._control = control
+
+  def handle_unary_unary(self, request, servicer_context):
+    self._control.control()
+    if servicer_context is not None:
+      servicer_context.set_trailing_metadata((('testkey', 'testvalue',),))
+    return request
+
+  def handle_unary_stream(self, request, servicer_context):
+    for _ in range(test_constants.STREAM_LENGTH):
+      self._control.control()
+      yield request
+    self._control.control()
+    if servicer_context is not None:
+      servicer_context.set_trailing_metadata((('testkey', 'testvalue',),))
+
+  def handle_stream_unary(self, request_iterator, servicer_context):
+    if servicer_context is not None:
+      servicer_context.invocation_metadata()
+    self._control.control()
+    response_elements = []
+    for request in request_iterator:
+      self._control.control()
+      response_elements.append(request)
+    self._control.control()
+    if servicer_context is not None:
+      servicer_context.set_trailing_metadata((('testkey', 'testvalue',),))
+    return b''.join(response_elements)
+
+  def handle_stream_stream(self, request_iterator, servicer_context):
+    self._control.control()
+    if servicer_context is not None:
+      servicer_context.set_trailing_metadata((('testkey', 'testvalue',),))
+    for request in request_iterator:
+      self._control.control()
+      yield request
+    self._control.control()
+
+
+class _MethodHandler(grpc.RpcMethodHandler):
+  def __init__(
+    self, request_streaming, response_streaming, request_deserializer,
+    response_serializer, unary_unary, unary_stream, stream_unary,
+    stream_stream):
+    self.request_streaming = request_streaming
+    self.response_streaming = response_streaming
+    self.request_deserializer = request_deserializer
+    self.response_serializer = response_serializer
+    self.unary_unary = unary_unary
+    self.unary_stream = unary_stream
+    self.stream_unary = stream_unary
+    self.stream_stream = stream_stream
+
+
+class _GenericHandler(grpc.GenericRpcHandler):
+  def __init__(self, handler):
+    self._handler = handler
+
+  def service(self, handler_call_details):
+    if handler_call_details.method == _UNARY_UNARY:
+      return _MethodHandler(
+        False, False, None, None, self._handler.handle_unary_unary, None,
+        None, None)
+    elif handler_call_details.method == _UNARY_STREAM:
+      return _MethodHandler(
+        False, True, _DESERIALIZE_REQUEST, _SERIALIZE_RESPONSE, None,
+        self._handler.handle_unary_stream, None, None)
+    elif handler_call_details.method == _STREAM_UNARY:
+      return _MethodHandler(
+        True, False, _DESERIALIZE_REQUEST, _SERIALIZE_RESPONSE, None, None,
+        self._handler.handle_stream_unary, None)
+    elif handler_call_details.method == _STREAM_STREAM:
+      return _MethodHandler(
+        True, True, None, None, None, None, None,
+        self._handler.handle_stream_stream)
+    else:
+      return None
+
+
+class FailAfterFewIterationsCounter(object):
+    def __init__(self, high, bytestring):
+        self._current = 0
+        self._high = high
+        self._bytestring = bytestring
+
+    def __iter__(self):
+        return self
+
+    def __next__(self):
+        if self._current >= self._high:
+            raise Exception("This is a deliberate failure in a unit test.")
+        else:
+            self._current += 1
+            return self._bytestring
+
+
+def _unary_unary_multi_callable(channel):
+  return channel.unary_unary(_UNARY_UNARY)
+
+
+def _unary_stream_multi_callable(channel):
+  return channel.unary_stream(
+    _UNARY_STREAM,
+    request_serializer=_SERIALIZE_REQUEST,
+    response_deserializer=_DESERIALIZE_RESPONSE)
+
+
+def _stream_unary_multi_callable(channel):
+  return channel.stream_unary(
+    _STREAM_UNARY,
+    request_serializer=_SERIALIZE_REQUEST,
+    response_deserializer=_DESERIALIZE_RESPONSE)
+
+
+def _stream_stream_multi_callable(channel):
+  return channel.stream_stream(_STREAM_STREAM)
+
+
+class InvocationDefectsTest(unittest.TestCase):
+  def setUp(self):
+    self._control = test_control.PauseFailControl()
+    self._handler = _Handler(self._control)
+    self._server_pool = logging_pool.pool(test_constants.THREAD_CONCURRENCY)
+
+    self._server = grpc.server(self._server_pool)
+    port = self._server.add_insecure_port('[::]:0')
+    self._server.add_generic_rpc_handlers((_GenericHandler(self._handler),))
+    self._server.start()
+
+    self._channel = grpc.insecure_channel('localhost:%d' % port)
+
+  def tearDown(self):
+    self._server.stop(0)
+
+  def testIterableStreamRequestBlockingUnaryResponse(self):
+    requests = [b'\x07\x08' for _ in range(test_constants.STREAM_LENGTH)]
+    multi_callable = _stream_unary_multi_callable(self._channel)
+
+    with self.assertRaises(grpc.RpcError):
+      response = multi_callable(
+        requests,
+        metadata=(('test', 'IterableStreamRequestBlockingUnaryResponse'),))
+
+  def testIterableStreamRequestFutureUnaryResponse(self):
+    requests = [b'\x07\x08' for _ in range(test_constants.STREAM_LENGTH)]
+    multi_callable = _stream_unary_multi_callable(self._channel)
+    response_future = multi_callable.future(
+      requests,
+      metadata=(
+        ('test', 'IterableStreamRequestFutureUnaryResponse'),))
+
+    with self.assertRaises(grpc.RpcError):
+      response = response_future.result()
+
+  def testIterableStreamRequestStreamResponse(self):
+    requests = [b'\x77\x58' for _ in range(test_constants.STREAM_LENGTH)]
+    multi_callable = _stream_stream_multi_callable(self._channel)
+    response_iterator = multi_callable(
+      requests,
+      metadata=(('test', 'IterableStreamRequestStreamResponse'),))
+
+    with self.assertRaises(grpc.RpcError):
+      next(response_iterator)
+
+  def testIteratorStreamRequestStreamResponse(self):
+    requests_iterator = FailAfterFewIterationsCounter(
+      test_constants.STREAM_LENGTH // 2, b'\x07\x08')
+    multi_callable = _stream_stream_multi_callable(self._channel)
+    response_iterator = multi_callable(
+      requests_iterator,
+      metadata=(('test', 'IteratorStreamRequestStreamResponse'),))
+
+    with self.assertRaises(grpc.RpcError):
+      for _ in range(test_constants.STREAM_LENGTH // 2 + 1):
+        next(response_iterator)
diff --git a/src/python/grpcio_tests/tests/unit/_metadata_test.py b/src/python/grpcio_tests/tests/unit/_metadata_test.py
index da73476929..caba53ffcc 100644
--- a/src/python/grpcio_tests/tests/unit/_metadata_test.py
+++ b/src/python/grpcio_tests/tests/unit/_metadata_test.py
@@ -193,7 +193,7 @@ class MetadataTest(unittest.TestCase):
   def testStreamUnary(self):
     multi_callable = self._channel.stream_unary(_STREAM_UNARY)
     unused_response, call = multi_callable.with_call(
-        [_REQUEST] * test_constants.STREAM_LENGTH,
+        iter([_REQUEST] * test_constants.STREAM_LENGTH),
         metadata=_CLIENT_METADATA)
     self.assertTrue(test_common.metadata_transmitted(
         _SERVER_INITIAL_METADATA, call.initial_metadata()))
@@ -202,7 +202,7 @@ class MetadataTest(unittest.TestCase):
 
   def testStreamStream(self):
     multi_callable = self._channel.stream_stream(_STREAM_STREAM)
-    call = multi_callable([_REQUEST] * test_constants.STREAM_LENGTH,
+    call = multi_callable(iter([_REQUEST] * test_constants.STREAM_LENGTH),
                           metadata=_CLIENT_METADATA)
     self.assertTrue(test_common.metadata_transmitted(
         _SERVER_INITIAL_METADATA, call.initial_metadata()))
diff --git a/src/ruby/lib/grpc/generic/bidi_call.rb b/src/ruby/lib/grpc/generic/bidi_call.rb
index 8943f3f1fe..adc77bbf5d 100644
--- a/src/ruby/lib/grpc/generic/bidi_call.rb
+++ b/src/ruby/lib/grpc/generic/bidi_call.rb
@@ -200,6 +200,7 @@ module GRPC
             if is_client
               batch_result = @call.run_batch(RECV_STATUS_ON_CLIENT => nil)
               @call.status = batch_result.status
+              @call.trailing_metadata = @call.status.metadata if @call.status
               batch_result.check_status
               GRPC.logger.debug("bidi-read-loop: done status #{@call.status}")
             end
diff --git a/src/ruby/lib/grpc/generic/service.rb b/src/ruby/lib/grpc/generic/service.rb
index 84f1ce7520..f5a6b49eb4 100644
--- a/src/ruby/lib/grpc/generic/service.rb
+++ b/src/ruby/lib/grpc/generic/service.rb
@@ -110,7 +110,7 @@ module GRPC
         rpc_descs[name] = RpcDesc.new(name, input, output,
                                       marshal_class_method,
                                       unmarshal_class_method)
-        define_method(GenericService.underscore(name.to_s).to_sym) do
+        define_method(GenericService.underscore(name.to_s).to_sym) do |_, _|
           fail GRPC::BadStatus.new_status_exception(
             GRPC::Core::StatusCodes::UNIMPLEMENTED)
         end
diff --git a/src/ruby/pb/src/proto/grpc/testing/test_services_pb.rb b/src/ruby/pb/src/proto/grpc/testing/test_services_pb.rb
index fde328e4c5..7d1072e512 100644
--- a/src/ruby/pb/src/proto/grpc/testing/test_services_pb.rb
+++ b/src/ruby/pb/src/proto/grpc/testing/test_services_pb.rb
@@ -54,6 +54,10 @@ module Grpc
         rpc :EmptyCall, Empty, Empty
         # One request followed by one response.
         rpc :UnaryCall, SimpleRequest, SimpleResponse
+        # One request followed by one response. Response has cache control
+        # headers set such that a caching HTTP proxy (such as GFE) can
+        # satisfy subsequent requests.
+        rpc :CacheableUnaryCall, SimpleRequest, SimpleResponse
         # One request followed by a sequence of responses (streamed download).
         # The server returns the payload with client desired type and sizes.
         rpc :StreamingOutputCall, StreamingOutputCallRequest, stream(StreamingOutputCallResponse)
@@ -69,6 +73,9 @@ module Grpc
         # stream of responses are returned to the client when the server starts with
         # first request.
         rpc :HalfDuplexCall, stream(StreamingOutputCallRequest), stream(StreamingOutputCallResponse)
+        # The test server will not implement this method. It will be used
+        # to test the behavior when clients call unimplemented methods.
+        rpc :UnimplementedCall, Empty, Empty
       end
 
       Stub = Service.rpc_stub_class
diff --git a/src/ruby/pb/test/client.rb b/src/ruby/pb/test/client.rb
index f101f9d89e..9c4ee9c6f2 100755
--- a/src/ruby/pb/test/client.rb
+++ b/src/ruby/pb/test/client.rb
@@ -158,14 +158,26 @@ def create_stub(opts)
 
     GRPC.logger.info("... connecting securely to #{address}")
     stub_opts[:channel_args].merge!(compression_channel_args)
-    Grpc::Testing::TestService::Stub.new(address, creds, **stub_opts)
+    if opts.test_case == "unimplemented_service"
+      Grpc::Testing::UnimplementedService::Stub.new(address, creds, **stub_opts)
+    else
+      Grpc::Testing::TestService::Stub.new(address, creds, **stub_opts)
+    end
   else
     GRPC.logger.info("... connecting insecurely to #{address}")
-    Grpc::Testing::TestService::Stub.new(
-      address,
-      :this_channel_is_insecure,
-      channel_args: compression_channel_args
-    )
+    if opts.test_case == "unimplemented_service"
+      Grpc::Testing::UnimplementedService::Stub.new(
+        address,
+        :this_channel_is_insecure,
+        channel_args: compression_channel_args
+      )
+    else
+      Grpc::Testing::TestService::Stub.new(
+        address,
+        :this_channel_is_insecure,
+        channel_args: compression_channel_args
+      )
+    end
   end
 end
 
@@ -502,6 +514,153 @@ class NamedTests
     op.wait
   end
 
+  def unimplemented_method
+    begin
+      resp = @stub.unimplemented_call(Empty.new)
+    rescue GRPC::Unimplemented => e
+      return
+    rescue Exception => e
+      fail AssertionError, "Expected BadStatus. Received: #{e.inspect}"
+    end
+    fail AssertionError, "GRPC::Unimplemented should have been raised. Was not."
+  end
+
+  def unimplemented_service
+    begin
+      resp = @stub.unimplemented_call(Empty.new)
+    rescue GRPC::Unimplemented => e
+      return
+    rescue Exception => e
+      fail AssertionError, "Expected BadStatus. Received: #{e.inspect}"
+    end
+    fail AssertionError, "GRPC::Unimplemented should have been raised. Was not."
+  end
+
+  def status_code_and_message
+
+    # Function wide constants.
+    message = "test status method"
+    code = GRPC::Core::StatusCodes::UNKNOWN
+
+    # Testing with UnaryCall.
+    payload = Payload.new(type: :COMPRESSABLE, body: nulls(1))
+    echo_status = EchoStatus.new(code: code, message: message)
+    req = SimpleRequest.new(response_type: :COMPRESSABLE,
+			    response_size: 1,
+			    payload: payload,
+			    response_status: echo_status)
+    seen_correct_exception = false
+    begin
+      resp = @stub.unary_call(req)
+    rescue GRPC::Unknown => e
+      if e.details != message
+	      fail AssertionError,
+	        "Expected message #{message}. Received: #{e.details}"
+      end
+      seen_correct_exception = true
+    rescue Exception => e
+      fail AssertionError, "Expected BadStatus. Received: #{e.inspect}"
+    end
+
+    if not seen_correct_exception
+      fail AssertionError, "Did not see expected status from UnaryCall"
+    end
+
+    # testing with FullDuplex
+    req_cls, p_cls = StreamingOutputCallRequest, ResponseParameters
+    duplex_req = req_cls.new(payload: Payload.new(body: nulls(1)),
+                  response_type: :COMPRESSABLE,
+                  response_parameters: [p_cls.new(size: 1)],
+                  response_status: echo_status)
+    seen_correct_exception = false
+    begin
+      resp = @stub.full_duplex_call([duplex_req])
+      resp.each { |r| }
+    rescue GRPC::Unknown => e
+      if e.details != message
+        fail AssertionError,
+          "Expected message #{message}. Received: #{e.details}"
+      end
+      seen_correct_exception = true
+    rescue Exception => e
+      fail AssertionError, "Expected BadStatus. Received: #{e.inspect}"
+    end
+
+    if not seen_correct_exception
+      fail AssertionError, "Did not see expected status from FullDuplexCall"
+    end
+
+  end
+
+
+  def custom_metadata
+
+    # Function wide constants
+    req_size, wanted_response_size = 271_828, 314_159
+    initial_metadata_key = "x-grpc-test-echo-initial"
+    initial_metadata_value = "test_initial_metadata_value"
+    trailing_metadata_key = "x-grpc-test-echo-trailing-bin"
+    trailing_metadata_value = "\x0a\x0b\x0a\x0b\x0a\x0b"
+
+    metadata = {
+      initial_metadata_key => initial_metadata_value,
+      trailing_metadata_key => trailing_metadata_value
+    }
+
+    # Testing with UnaryCall
+    payload = Payload.new(type: :COMPRESSABLE, body: nulls(req_size))
+    req = SimpleRequest.new(response_type: :COMPRESSABLE,
+			    response_size: wanted_response_size,
+			    payload: payload)
+
+    op = @stub.unary_call(req, metadata: metadata, return_op: true)
+    op.execute
+    if not op.metadata.has_key?(initial_metadata_key)
+      fail AssertionError, "Expected initial metadata. None received"
+    elsif op.metadata[initial_metadata_key] != metadata[initial_metadata_key]
+      fail AssertionError, 
+             "Expected initial metadata: #{metadata[initial_metadata_key]}. "\
+             "Received: #{op.metadata[initial_metadata_key]}"
+    end
+    if not op.trailing_metadata.has_key?(trailing_metadata_key)
+      fail AssertionError, "Expected trailing metadata. None received"
+    elsif op.trailing_metadata[trailing_metadata_key] !=
+          metadata[trailing_metadata_key]
+      fail AssertionError, 
+            "Expected trailing metadata: #{metadata[trailing_metadata_key]}. "\
+            "Received: #{op.trailing_metadata[trailing_metadata_key]}"
+    end
+
+    # Testing with FullDuplex
+    req_cls, p_cls = StreamingOutputCallRequest, ResponseParameters
+    duplex_req = req_cls.new(payload: Payload.new(body: nulls(req_size)),
+                  response_type: :COMPRESSABLE,
+                  response_parameters: [p_cls.new(size: wanted_response_size)])
+
+    duplex_op = @stub.full_duplex_call([duplex_req], metadata: metadata,
+                                        return_op: true)
+    resp = duplex_op.execute
+    resp.each { |r| } # ensures that the server sends trailing data
+    duplex_op.wait
+    if not duplex_op.metadata.has_key?(initial_metadata_key)
+      fail AssertionError, "Expected initial metadata. None received"
+    elsif duplex_op.metadata[initial_metadata_key] !=
+          metadata[initial_metadata_key]
+      fail AssertionError,
+             "Expected initial metadata: #{metadata[initial_metadata_key]}. "\
+             "Received: #{duplex_op.metadata[initial_metadata_key]}"
+    end
+    if not duplex_op.trailing_metadata[trailing_metadata_key]
+      fail AssertionError, "Expected trailing metadata. None received"
+    elsif duplex_op.trailing_metadata[trailing_metadata_key] !=
+          metadata[trailing_metadata_key]
+      fail AssertionError, 
+          "Expected trailing metadata: #{metadata[trailing_metadata_key]}. "\
+          "Received: #{duplex_op.trailing_metadata[trailing_metadata_key]}"
+    end
+
+  end
+
   def all
     all_methods = NamedTests.instance_methods(false).map(&:to_s)
     all_methods.each do |m|
diff --git a/src/ruby/pb/test/server.rb b/src/ruby/pb/test/server.rb
index 3f1e0a1ccf..cc9b872648 100755
--- a/src/ruby/pb/test/server.rb
+++ b/src/ruby/pb/test/server.rb
@@ -129,6 +129,27 @@ def nulls(l)
   [].pack('x' * l).force_encoding('ascii-8bit')
 end
 
+def maybe_echo_metadata(_call)
+  
+  # these are consistent for all interop tests
+  initial_metadata_key = "x-grpc-test-echo-initial"
+  trailing_metadata_key = "x-grpc-test-echo-trailing-bin"
+
+  if _call.metadata.has_key?(initial_metadata_key)
+    _call.metadata_to_send[initial_metadata_key] = _call.metadata[initial_metadata_key]
+  end
+  if _call.metadata.has_key?(trailing_metadata_key)
+    _call.output_metadata[trailing_metadata_key] = _call.metadata[trailing_metadata_key]
+  end
+end
+
+def maybe_echo_status_and_message(req)
+  unless req.response_status.nil?
+    fail GRPC::BadStatus.new_status_exception(
+        req.response_status.code, req.response_status.message)
+  end
+end
+
 # A FullDuplexEnumerator passes requests to a block and yields generated responses
 class FullDuplexEnumerator
   include Grpc::Testing
@@ -143,6 +164,7 @@ class FullDuplexEnumerator
     begin
       cls = StreamingOutputCallResponse
       @requests.each do |req|
+        maybe_echo_status_and_message(req)
         req.response_parameters.each do |params|
           resp_size = params.size
           GRPC.logger.info("read a req, response size is #{resp_size}")
@@ -170,6 +192,8 @@ class TestTarget < Grpc::Testing::TestService::Service
   end
 
   def unary_call(simple_req, _call)
+    maybe_echo_metadata(_call)
+    maybe_echo_status_and_message(simple_req)
     req_size = simple_req.response_size
     SimpleResponse.new(payload: Payload.new(type: :COMPRESSABLE,
                                             body: nulls(req_size)))
@@ -189,7 +213,8 @@ class TestTarget < Grpc::Testing::TestService::Service
     end
   end
 
-  def full_duplex_call(reqs)
+  def full_duplex_call(reqs, _call)
+    maybe_echo_metadata(_call)
     # reqs is a lazy Enumerator of the requests sent by the client.
     FullDuplexEnumerator.new(reqs).each_item
   end
diff --git a/src/ruby/spec/generic/rpc_server_pool_spec.rb b/src/ruby/spec/generic/rpc_server_pool_spec.rb
index 48ccaee510..69e8222cb9 100644
--- a/src/ruby/spec/generic/rpc_server_pool_spec.rb
+++ b/src/ruby/spec/generic/rpc_server_pool_spec.rb
@@ -94,18 +94,6 @@ describe GRPC::Pool do
       expect(q.pop).to be(o)
       p.stop
     end
-
-    it 'it throws an error if all of the workers have tasks to do' do
-      p = Pool.new(5)
-      p.start
-      job = proc {}
-      5.times do
-        expect(p.ready_for_work?).to be(true)
-        p.schedule(&job)
-      end
-      expect { p.schedule(&job) }.to raise_error
-      expect { p.schedule(&job) }.to raise_error
-    end
   end
 
   describe '#stop' do