Merging master into yashykt:ctocc6

77 files changed, 1296 insertions, 559 deletions

diff --git a/BUILD b/BUILD
index 281375fc1d..7b55e663cb 100644
--- a/BUILD
+++ b/BUILD
@@ -574,6 +574,8 @@ grpc_cc_library(
         "src/core/lib/compression/compression.c",
         "src/core/lib/compression/message_compress.c",
         "src/core/lib/compression/stream_compression.c",
+        "src/core/lib/debug/stats.c",
+        "src/core/lib/debug/stats_data.c",
         "src/core/lib/http/format_request.c",
         "src/core/lib/http/httpcli.c",
         "src/core/lib/http/parser.c",
@@ -690,8 +692,6 @@ grpc_cc_library(
         "src/core/lib/transport/timeout_encoding.c",
         "src/core/lib/transport/transport.c",
         "src/core/lib/transport/transport_op_string.c",
-        "src/core/lib/debug/stats.c",
-        "src/core/lib/debug/stats_data.c",
     ],
     hdrs = [
         "src/core/lib/channel/channel_args.h",
@@ -705,6 +705,8 @@ grpc_cc_library(
         "src/core/lib/compression/algorithm_metadata.h",
         "src/core/lib/compression/message_compress.h",
         "src/core/lib/compression/stream_compression.h",
+        "src/core/lib/debug/stats.h",
+        "src/core/lib/debug/stats_data.h",
         "src/core/lib/http/format_request.h",
         "src/core/lib/http/httpcli.h",
         "src/core/lib/http/parser.h",
@@ -807,8 +809,6 @@ grpc_cc_library(
         "src/core/lib/transport/timeout_encoding.h",
         "src/core/lib/transport/transport.h",
         "src/core/lib/transport/transport_impl.h",
-        "src/core/lib/debug/stats.h",
-        "src/core/lib/debug/stats_data.h",
     ],
     external_deps = [
         "zlib",
diff --git a/config.m4 b/config.m4
index d52e37ca28..656a37e9b4 100644
--- a/config.m4
+++ b/config.m4
@@ -12,7 +12,7 @@ if test "$PHP_GRPC" != "no"; then
   LIBS="-lpthread $LIBS"
 
   CFLAGS="-Wall -Werror -Wno-parentheses-equality -Wno-unused-value -std=c11"
-  CXXFLAGS="-std=c++11"
+  CXXFLAGS="-std=c++11 -fno-exceptions -fno-rtti"
   GRPC_SHARED_LIBADD="-lpthread $GRPC_SHARED_LIBADD"
   PHP_REQUIRE_CXX()
   PHP_ADD_LIBRARY(pthread)
diff --git a/doc/environment_variables.md b/doc/environment_variables.md
index b79cd97363..f90f1d5b10 100644
--- a/doc/environment_variables.md
+++ b/doc/environment_variables.md
@@ -50,6 +50,7 @@ some configuration as environment variables that can be set.
   - channel_stack_builder - traces information about channel stacks being built
   - executor - traces grpc's internal thread pool ('the executor')
   - http - traces state in the http2 transport engine
+  - http2_stream_state - traces all http2 stream state mutations.
   - http1 - traces HTTP/1.x operations performed by gRPC
   - inproc - traces the in-process transport
   - flowctl - traces http2 flow control
diff --git a/grpc.gemspec b/grpc.gemspec
index 2d0f9fd450..96323aed10 100644
--- a/grpc.gemspec
+++ b/grpc.gemspec
@@ -29,6 +29,7 @@ Gem::Specification.new do |s|
 
   s.add_dependency 'google-protobuf', '~> 3.1'
   s.add_dependency 'googleauth',      '~> 0.5.1'
+  s.add_dependency 'googleapis-common-protos-types', '~> 1.0.0'
 
   s.add_development_dependency 'bundler',            '~> 1.9'
   s.add_development_dependency 'facter',             '~> 2.4'
diff --git a/include/grpc/impl/codegen/grpc_types.h b/include/grpc/impl/codegen/grpc_types.h
index 748dc717a3..90f03f49a3 100644
--- a/include/grpc/impl/codegen/grpc_types.h
+++ b/include/grpc/impl/codegen/grpc_types.h
@@ -188,9 +188,14 @@ typedef struct {
 #define GRPC_ARG_HTTP2_MAX_FRAME_SIZE "grpc.http2.max_frame_size"
 /** Should BDP probing be performed? */
 #define GRPC_ARG_HTTP2_BDP_PROBE "grpc.http2.bdp_probe"
-/** Minimum time (in milliseconds) between successive ping frames being sent */
-#define GRPC_ARG_HTTP2_MIN_TIME_BETWEEN_PINGS_MS \
+/** Minimum time between sending successive ping frames without receiving any
+    data frame, Int valued, milliseconds. */
+#define GRPC_ARG_HTTP2_MIN_SENT_PING_INTERVAL_WITHOUT_DATA_MS \
   "grpc.http2.min_time_between_pings_ms"
+/** Minimum allowed time between receiving successive ping frames without
+    sending any data frame. Int valued, milliseconds */
+#define GRPC_ARG_HTTP2_MIN_RECV_PING_INTERVAL_WITHOUT_DATA_MS \
+  "grpc.http2.min_ping_interval_without_data_ms"
 /** Channel arg to override the http2 :scheme header */
 #define GRPC_ARG_HTTP2_SCHEME "grpc.http2_scheme"
 /** How many pings can we send before needing to send a data frame or header
@@ -202,10 +207,6 @@ typedef struct {
     closing the transport? (0 indicates that the server can bear an infinite
     number of misbehaving pings) */
 #define GRPC_ARG_HTTP2_MAX_PING_STRIKES "grpc.http2.max_ping_strikes"
-/** Minimum allowed time between two pings without sending any data frame. Int
-    valued, seconds */
-#define GRPC_ARG_HTTP2_MIN_PING_INTERVAL_WITHOUT_DATA_MS \
-  "grpc.http2.min_ping_interval_without_data_ms"
 /** How much data are we willing to queue up per stream if
     GRPC_WRITE_BUFFER_HINT is set? This is an upper bound */
 #define GRPC_ARG_HTTP2_WRITE_BUFFER_SIZE "grpc.http2.write_buffer_size"
diff --git a/package.xml b/package.xml
index b7c0e679e5..0c201afdae 100644
--- a/package.xml
+++ b/package.xml
@@ -10,7 +10,7 @@
   <email>grpc-packages@google.com</email>
   <active>yes</active>
  </lead>
- <date>2017-05-22</date>
+ <date>2017-08-24</date>
  <time>16:06:07</time>
  <version>
   <release>1.7.0dev</release>
@@ -25,6 +25,9 @@
 - Channel are now by default persistent #11878
 - Some bug fixes from 1.4 branch #12109, #12123
 - Fixed hang bug when fork() was used #11814
+- License changed to Apache 2.0
+- Added support for php_namespace option in codegen plugin #11886
+- Updated gRPC C Core library version 1.6
  </notes>
  <contents>
   <dir baseinstalldir="/" name="/">
diff --git a/setup.py b/setup.py
index d3ea83488c..12882413ce 100644
--- a/setup.py
+++ b/setup.py
@@ -70,7 +70,7 @@ CLASSIFIERS = [
     'Programming Language :: Python :: 3.5',
     'Programming Language :: Python :: 3.6',
     'License :: OSI Approved :: Apache Software License',
-],
+]
 
 # Environment variable to determine whether or not the Cython extension should
 # *use* Cython or use the generated C files. Note that this requires the C files
diff --git a/src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb.c b/src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb.c
index c4c4973b2d..85ef7894ea 100644
--- a/src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb.c
+++ b/src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb.c
@@ -1560,6 +1560,9 @@ static void lb_on_response_received_locked(grpc_exec_ctx *exec_ctx, void *arg,
           exec_ctx, glb_policy->lb_call, ops, (size_t)(op - ops),
           &glb_policy->lb_on_response_received); /* loop */
       GPR_ASSERT(GRPC_CALL_OK == call_error);
+    } else {
+      GRPC_LB_POLICY_WEAK_UNREF(exec_ctx, &glb_policy->base,
+                                "lb_on_response_received_locked_shutdown");
     }
   } else { /* empty payload: call cancelled. */
            /* dispose of the "lb_on_response_received_locked" weak ref taken in
diff --git a/src/core/ext/transport/chttp2/transport/chttp2_plugin.c b/src/core/ext/transport/chttp2/transport/chttp2_plugin.c
index 78551df9c3..6d09953830 100644
--- a/src/core/ext/transport/chttp2/transport/chttp2_plugin.c
+++ b/src/core/ext/transport/chttp2/transport/chttp2_plugin.c
@@ -23,6 +23,7 @@
 void grpc_chttp2_plugin_init(void) {
   grpc_register_tracer(&grpc_http_trace);
   grpc_register_tracer(&grpc_flowctl_trace);
+  grpc_register_tracer(&grpc_trace_http2_stream_state);
 #ifndef NDEBUG
   grpc_register_tracer(&grpc_trace_chttp2_refcount);
 #endif
diff --git a/src/core/ext/transport/chttp2/transport/chttp2_transport.c b/src/core/ext/transport/chttp2/transport/chttp2_transport.c
index d18df04851..1a6e08fd0b 100644
--- a/src/core/ext/transport/chttp2/transport/chttp2_transport.c
+++ b/src/core/ext/transport/chttp2/transport/chttp2_transport.c
@@ -64,6 +64,11 @@
 #define DEFAULT_KEEPALIVE_PERMIT_WITHOUT_CALLS false
 #define KEEPALIVE_TIME_BACKOFF_MULTIPLIER 2
 
+#define DEFAULT_MIN_SENT_PING_INTERVAL_WITHOUT_DATA_MS 300000 /* 5 minutes */
+#define DEFAULT_MIN_RECV_PING_INTERVAL_WITHOUT_DATA_MS 300000 /* 5 minutes */
+#define DEFAULT_MAX_PINGS_BETWEEN_DATA 0                      /* unlimited */
+#define DEFAULT_MAX_PING_STRIKES 2
+
 static int g_default_client_keepalive_time_ms =
     DEFAULT_CLIENT_KEEPALIVE_TIME_MS;
 static int g_default_client_keepalive_timeout_ms =
@@ -75,6 +80,13 @@ static int g_default_server_keepalive_timeout_ms =
 static bool g_default_keepalive_permit_without_calls =
     DEFAULT_KEEPALIVE_PERMIT_WITHOUT_CALLS;
 
+static int g_default_min_sent_ping_interval_without_data_ms =
+    DEFAULT_MIN_SENT_PING_INTERVAL_WITHOUT_DATA_MS;
+static int g_default_min_recv_ping_interval_without_data_ms =
+    DEFAULT_MIN_RECV_PING_INTERVAL_WITHOUT_DATA_MS;
+static int g_default_max_pings_without_data = DEFAULT_MAX_PINGS_BETWEEN_DATA;
+static int g_default_max_ping_strikes = DEFAULT_MAX_PING_STRIKES;
+
 #define MAX_CLIENT_STREAM_ID 0x7fffffffu
 grpc_tracer_flag grpc_http_trace = GRPC_TRACER_INITIALIZER(false, "http");
 grpc_tracer_flag grpc_flowctl_trace = GRPC_TRACER_INITIALIZER(false, "flowctl");
@@ -152,11 +164,6 @@ static void send_ping_locked(
 static void retry_initiate_ping_locked(grpc_exec_ctx *exec_ctx, void *tp,
                                        grpc_error *error);
 
-#define DEFAULT_MIN_TIME_BETWEEN_PINGS_MS 0
-#define DEFAULT_MAX_PINGS_BETWEEN_DATA 3
-#define DEFAULT_MAX_PING_STRIKES 2
-#define DEFAULT_MIN_PING_INTERVAL_WITHOUT_DATA_MS 300000 /* 5 minutes */
-
 /** keepalive-relevant functions */
 static void init_keepalive_ping_locked(grpc_exec_ctx *exec_ctx, void *arg,
                                        grpc_error *error);
@@ -362,12 +369,12 @@ static void init_transport(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
   queue_setting_update(exec_ctx, t,
                        GRPC_CHTTP2_SETTINGS_GRPC_ALLOW_TRUE_BINARY_METADATA, 1);
 
-  t->ping_policy.max_pings_without_data = DEFAULT_MAX_PINGS_BETWEEN_DATA;
-  t->ping_policy.min_time_between_pings =
-      gpr_time_from_millis(DEFAULT_MIN_TIME_BETWEEN_PINGS_MS, GPR_TIMESPAN);
-  t->ping_policy.max_ping_strikes = DEFAULT_MAX_PING_STRIKES;
-  t->ping_policy.min_ping_interval_without_data = gpr_time_from_millis(
-      DEFAULT_MIN_PING_INTERVAL_WITHOUT_DATA_MS, GPR_TIMESPAN);
+  t->ping_policy.max_pings_without_data = g_default_max_pings_without_data;
+  t->ping_policy.min_sent_ping_interval_without_data = gpr_time_from_millis(
+      g_default_min_sent_ping_interval_without_data_ms, GPR_TIMESPAN);
+  t->ping_policy.max_ping_strikes = g_default_max_ping_strikes;
+  t->ping_policy.min_recv_ping_interval_without_data = gpr_time_from_millis(
+      g_default_min_recv_ping_interval_without_data_ms, GPR_TIMESPAN);
 
   /* Keepalive setting */
   if (t->is_client) {
@@ -426,29 +433,37 @@ static void init_transport(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
                              GRPC_ARG_HTTP2_MAX_PINGS_WITHOUT_DATA)) {
         t->ping_policy.max_pings_without_data = grpc_channel_arg_get_integer(
             &channel_args->args[i],
-            (grpc_integer_options){DEFAULT_MAX_PINGS_BETWEEN_DATA, 0, INT_MAX});
+            (grpc_integer_options){g_default_max_pings_without_data, 0,
+                                   INT_MAX});
       } else if (0 == strcmp(channel_args->args[i].key,
                              GRPC_ARG_HTTP2_MAX_PING_STRIKES)) {
         t->ping_policy.max_ping_strikes = grpc_channel_arg_get_integer(
             &channel_args->args[i],
-            (grpc_integer_options){DEFAULT_MAX_PING_STRIKES, 0, INT_MAX});
-      } else if (0 == strcmp(channel_args->args[i].key,
-                             GRPC_ARG_HTTP2_MIN_TIME_BETWEEN_PINGS_MS)) {
-        t->ping_policy.min_time_between_pings = gpr_time_from_millis(
-            grpc_channel_arg_get_integer(
-                &channel_args->args[i],
-                (grpc_integer_options){DEFAULT_MIN_TIME_BETWEEN_PINGS_MS, 0,
-                                       INT_MAX}),
-            GPR_TIMESPAN);
+            (grpc_integer_options){g_default_max_ping_strikes, 0, INT_MAX});
       } else if (0 ==
-                 strcmp(channel_args->args[i].key,
-                        GRPC_ARG_HTTP2_MIN_PING_INTERVAL_WITHOUT_DATA_MS)) {
-        t->ping_policy.min_ping_interval_without_data = gpr_time_from_millis(
-            grpc_channel_arg_get_integer(
-                &channel_args->args[i],
-                (grpc_integer_options){
-                    DEFAULT_MIN_PING_INTERVAL_WITHOUT_DATA_MS, 0, INT_MAX}),
-            GPR_TIMESPAN);
+                 strcmp(
+                     channel_args->args[i].key,
+                     GRPC_ARG_HTTP2_MIN_SENT_PING_INTERVAL_WITHOUT_DATA_MS)) {
+        t->ping_policy.min_sent_ping_interval_without_data =
+            gpr_time_from_millis(
+                grpc_channel_arg_get_integer(
+                    &channel_args->args[i],
+                    (grpc_integer_options){
+                        g_default_min_sent_ping_interval_without_data_ms, 0,
+                        INT_MAX}),
+                GPR_TIMESPAN);
+      } else if (0 ==
+                 strcmp(
+                     channel_args->args[i].key,
+                     GRPC_ARG_HTTP2_MIN_RECV_PING_INTERVAL_WITHOUT_DATA_MS)) {
+        t->ping_policy.min_recv_ping_interval_without_data =
+            gpr_time_from_millis(
+                grpc_channel_arg_get_integer(
+                    &channel_args->args[i],
+                    (grpc_integer_options){
+                        g_default_min_recv_ping_interval_without_data_ms, 0,
+                        INT_MAX}),
+                GPR_TIMESPAN);
       } else if (0 == strcmp(channel_args->args[i].key,
                              GRPC_ARG_HTTP2_WRITE_BUFFER_SIZE)) {
         t->write_buffer_size = (uint32_t)grpc_channel_arg_get_integer(
@@ -555,8 +570,8 @@ static void init_transport(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
     }
   }
 
-  t->ping_state.pings_before_data_required =
-      t->ping_policy.max_pings_without_data;
+  /* No pings allowed before receiving a header or data frame. */
+  t->ping_state.pings_before_data_required = 0;
   t->ping_state.is_delayed_ping_timer_set = false;
 
   t->ping_recv_state.last_ping_recv_time = gpr_inf_past(GPR_CLOCK_MONOTONIC);
@@ -623,6 +638,9 @@ static void close_transport_locked(grpc_exec_ctx *exec_ctx,
     connectivity_state_set(exec_ctx, t, GRPC_CHANNEL_SHUTDOWN,
                            GRPC_ERROR_REF(error), "close_transport");
     grpc_endpoint_shutdown(exec_ctx, t->ep, GRPC_ERROR_REF(error));
+    if (t->ping_state.is_delayed_ping_timer_set) {
+      grpc_timer_cancel(exec_ctx, &t->ping_state.delayed_ping_timer);
+    }
     switch (t->keepalive_state) {
       case GRPC_CHTTP2_KEEPALIVE_STATE_WAITING:
         grpc_timer_cancel(exec_ctx, &t->keepalive_ping_timer);
@@ -1727,8 +1745,10 @@ static void retry_initiate_ping_locked(grpc_exec_ctx *exec_ctx, void *tp,
                                        grpc_error *error) {
   grpc_chttp2_transport *t = (grpc_chttp2_transport *)tp;
   t->ping_state.is_delayed_ping_timer_set = false;
-  grpc_chttp2_initiate_write(exec_ctx, t,
-                             GRPC_CHTTP2_INITIATE_WRITE_RETRY_SEND_PING);
+  if (error == GRPC_ERROR_NONE) {
+    grpc_chttp2_initiate_write(exec_ctx, t,
+                               GRPC_CHTTP2_INITIATE_WRITE_RETRY_SEND_PING);
+  }
 }
 
 void grpc_chttp2_ack_ping(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
@@ -2629,6 +2649,36 @@ void grpc_chttp2_config_default_keepalive_args(grpc_channel_args *args,
                 &args->args[i],
                 (grpc_integer_options){g_default_keepalive_permit_without_calls,
                                        0, 1});
+      } else if (0 ==
+                 strcmp(args->args[i].key, GRPC_ARG_HTTP2_MAX_PING_STRIKES)) {
+        g_default_max_ping_strikes = grpc_channel_arg_get_integer(
+            &args->args[i],
+            (grpc_integer_options){g_default_max_ping_strikes, 0, INT_MAX});
+      } else if (0 == strcmp(args->args[i].key,
+                             GRPC_ARG_HTTP2_MAX_PINGS_WITHOUT_DATA)) {
+        g_default_max_pings_without_data = grpc_channel_arg_get_integer(
+            &args->args[i], (grpc_integer_options){
+                                g_default_max_pings_without_data, 0, INT_MAX});
+      } else if (0 ==
+                 strcmp(
+                     args->args[i].key,
+                     GRPC_ARG_HTTP2_MIN_SENT_PING_INTERVAL_WITHOUT_DATA_MS)) {
+        g_default_min_sent_ping_interval_without_data_ms =
+            grpc_channel_arg_get_integer(
+                &args->args[i],
+                (grpc_integer_options){
+                    g_default_min_sent_ping_interval_without_data_ms, 0,
+                    INT_MAX});
+      } else if (0 ==
+                 strcmp(
+                     args->args[i].key,
+                     GRPC_ARG_HTTP2_MIN_RECV_PING_INTERVAL_WITHOUT_DATA_MS)) {
+        g_default_min_recv_ping_interval_without_data_ms =
+            grpc_channel_arg_get_integer(
+                &args->args[i],
+                (grpc_integer_options){
+                    g_default_min_recv_ping_interval_without_data_ms, 0,
+                    INT_MAX});
       }
     }
   }
diff --git a/src/core/ext/transport/chttp2/transport/chttp2_transport.h b/src/core/ext/transport/chttp2/transport/chttp2_transport.h
index 0c4e2a91c0..55fb1a8343 100644
--- a/src/core/ext/transport/chttp2/transport/chttp2_transport.h
+++ b/src/core/ext/transport/chttp2/transport/chttp2_transport.h
@@ -25,6 +25,7 @@
 
 extern grpc_tracer_flag grpc_http_trace;
 extern grpc_tracer_flag grpc_flowctl_trace;
+extern grpc_tracer_flag grpc_trace_http2_stream_state;
 
 #ifndef NDEBUG
 extern grpc_tracer_flag grpc_trace_chttp2_refcount;
diff --git a/src/core/ext/transport/chttp2/transport/frame_ping.c b/src/core/ext/transport/chttp2/transport/frame_ping.c
index 81bd02ae70..d431d6b2df 100644
--- a/src/core/ext/transport/chttp2/transport/frame_ping.c
+++ b/src/core/ext/transport/chttp2/transport/frame_ping.c
@@ -92,7 +92,7 @@ grpc_error *grpc_chttp2_ping_parser_parse(grpc_exec_ctx *exec_ctx, void *parser,
         gpr_timespec now = gpr_now(GPR_CLOCK_MONOTONIC);
         gpr_timespec next_allowed_ping =
             gpr_time_add(t->ping_recv_state.last_ping_recv_time,
-                         t->ping_policy.min_ping_interval_without_data);
+                         t->ping_policy.min_recv_ping_interval_without_data);
 
         if (t->keepalive_permit_without_calls == 0 &&
             grpc_chttp2_stream_map_size(&t->stream_map) == 0) {
diff --git a/src/core/ext/transport/chttp2/transport/internal.h b/src/core/ext/transport/chttp2/transport/internal.h
index c2dfce7c9c..1682be28dd 100644
--- a/src/core/ext/transport/chttp2/transport/internal.h
+++ b/src/core/ext/transport/chttp2/transport/internal.h
@@ -112,10 +112,10 @@ typedef struct {
 } grpc_chttp2_ping_queue;
 
 typedef struct {
-  gpr_timespec min_time_between_pings;
   int max_pings_without_data;
   int max_ping_strikes;
-  gpr_timespec min_ping_interval_without_data;
+  gpr_timespec min_sent_ping_interval_without_data;
+  gpr_timespec min_recv_ping_interval_without_data;
 } grpc_chttp2_repeated_ping_policy;
 
 typedef struct {
diff --git a/src/core/ext/transport/chttp2/transport/parsing.c b/src/core/ext/transport/chttp2/transport/parsing.c
index 6c12c91365..3db1ad4123 100644
--- a/src/core/ext/transport/chttp2/transport/parsing.c
+++ b/src/core/ext/transport/chttp2/transport/parsing.c
@@ -383,6 +383,9 @@ error_handler:
     /* t->parser = grpc_chttp2_data_parser_parse;*/
     t->parser = grpc_chttp2_data_parser_parse;
     t->parser_data = &s->data_parser;
+    t->ping_state.pings_before_data_required =
+        t->ping_policy.max_pings_without_data;
+    t->ping_state.last_ping_sent_time = gpr_inf_past(GPR_CLOCK_MONOTONIC);
     return GRPC_ERROR_NONE;
   } else if (grpc_error_get_int(err, GRPC_ERROR_INT_STREAM_ID, NULL)) {
     /* handle stream errors by closing the stream */
@@ -559,6 +562,10 @@ static grpc_error *init_header_frame_parser(grpc_exec_ctx *exec_ctx,
         (t->incoming_frame_flags & GRPC_CHTTP2_DATA_FLAG_END_STREAM) != 0;
   }
 
+  t->ping_state.pings_before_data_required =
+      t->ping_policy.max_pings_without_data;
+  t->ping_state.last_ping_sent_time = gpr_inf_past(GPR_CLOCK_MONOTONIC);
+
   /* could be a new grpc_chttp2_stream or an existing grpc_chttp2_stream */
   s = grpc_chttp2_parsing_lookup_stream(t, t->incoming_stream_id);
   if (s == NULL) {
diff --git a/src/core/ext/transport/chttp2/transport/stream_lists.c b/src/core/ext/transport/chttp2/transport/stream_lists.c
index 7cc85dea9c..47cd22d177 100644
--- a/src/core/ext/transport/chttp2/transport/stream_lists.c
+++ b/src/core/ext/transport/chttp2/transport/stream_lists.c
@@ -20,6 +20,27 @@
 
 #include <grpc/support/log.h>
 
+static char *stream_list_id_string(grpc_chttp2_stream_list_id id) {
+  switch (id) {
+    case GRPC_CHTTP2_LIST_WRITABLE:
+      return "writable";
+    case GRPC_CHTTP2_LIST_WRITING:
+      return "writing";
+    case GRPC_CHTTP2_LIST_STALLED_BY_TRANSPORT:
+      return "stalled_by_transport";
+    case GRPC_CHTTP2_LIST_STALLED_BY_STREAM:
+      return "stalled_by_stream";
+    case GRPC_CHTTP2_LIST_WAITING_FOR_CONCURRENCY:
+      return "waiting_for_concurrency";
+    case STREAM_LIST_COUNT:
+      GPR_UNREACHABLE_CODE(return "unknown");
+  }
+  GPR_UNREACHABLE_CODE(return "unknown");
+}
+
+grpc_tracer_flag grpc_trace_http2_stream_state =
+    GRPC_TRACER_INITIALIZER(false, "http2_stream_state");
+
 /* core list management */
 
 static bool stream_list_empty(grpc_chttp2_transport *t,
@@ -44,6 +65,10 @@ static bool stream_list_pop(grpc_chttp2_transport *t,
     s->included[id] = 0;
   }
   *stream = s;
+  if (s && GRPC_TRACER_ON(grpc_trace_http2_stream_state)) {
+    gpr_log(GPR_DEBUG, "%p[%d][%s]: pop from %s", t, s->id,
+            t->is_client ? "cli" : "svr", stream_list_id_string(id));
+  }
   return s != 0;
 }
 
@@ -62,6 +87,10 @@ static void stream_list_remove(grpc_chttp2_transport *t, grpc_chttp2_stream *s,
   } else {
     t->lists[id].tail = s->links[id].prev;
   }
+  if (GRPC_TRACER_ON(grpc_trace_http2_stream_state)) {
+    gpr_log(GPR_DEBUG, "%p[%d][%s]: remove from %s", t, s->id,
+            t->is_client ? "cli" : "svr", stream_list_id_string(id));
+  }
 }
 
 static bool stream_list_maybe_remove(grpc_chttp2_transport *t,
@@ -90,6 +119,10 @@ static void stream_list_add_tail(grpc_chttp2_transport *t,
   }
   t->lists[id].tail = s;
   s->included[id] = 1;
+  if (GRPC_TRACER_ON(grpc_trace_http2_stream_state)) {
+    gpr_log(GPR_DEBUG, "%p[%d][%s]: add to %s", t, s->id,
+            t->is_client ? "cli" : "svr", stream_list_id_string(id));
+  }
 }
 
 static bool stream_list_add(grpc_chttp2_transport *t, grpc_chttp2_stream *s,
@@ -150,17 +183,12 @@ void grpc_chttp2_list_remove_waiting_for_concurrency(grpc_chttp2_transport *t,
 
 void grpc_chttp2_list_add_stalled_by_transport(grpc_chttp2_transport *t,
                                                grpc_chttp2_stream *s) {
-  GRPC_FLOW_CONTROL_IF_TRACING(
-      gpr_log(GPR_DEBUG, "stream %u stalled by transport", s->id));
   stream_list_add(t, s, GRPC_CHTTP2_LIST_STALLED_BY_TRANSPORT);
 }
 
 bool grpc_chttp2_list_pop_stalled_by_transport(grpc_chttp2_transport *t,
                                                grpc_chttp2_stream **s) {
-  bool ret = stream_list_pop(t, s, GRPC_CHTTP2_LIST_STALLED_BY_TRANSPORT);
-  GRPC_FLOW_CONTROL_IF_TRACING(if (ret) gpr_log(
-      GPR_DEBUG, "stream %u un-stalled by transport", (*s)->id));
-  return ret;
+  return stream_list_pop(t, s, GRPC_CHTTP2_LIST_STALLED_BY_TRANSPORT);
 }
 
 void grpc_chttp2_list_remove_stalled_by_transport(grpc_chttp2_transport *t,
@@ -170,23 +198,15 @@ void grpc_chttp2_list_remove_stalled_by_transport(grpc_chttp2_transport *t,
 
 void grpc_chttp2_list_add_stalled_by_stream(grpc_chttp2_transport *t,
                                             grpc_chttp2_stream *s) {
-  GRPC_FLOW_CONTROL_IF_TRACING(
-      gpr_log(GPR_DEBUG, "stream %u stalled by stream", s->id));
   stream_list_add(t, s, GRPC_CHTTP2_LIST_STALLED_BY_STREAM);
 }
 
 bool grpc_chttp2_list_pop_stalled_by_stream(grpc_chttp2_transport *t,
                                             grpc_chttp2_stream **s) {
-  bool ret = stream_list_pop(t, s, GRPC_CHTTP2_LIST_STALLED_BY_STREAM);
-  GRPC_FLOW_CONTROL_IF_TRACING(
-      if (ret) gpr_log(GPR_DEBUG, "stream %u un-stalled by stream", (*s)->id));
-  return ret;
+  return stream_list_pop(t, s, GRPC_CHTTP2_LIST_STALLED_BY_STREAM);
 }
 
 bool grpc_chttp2_list_remove_stalled_by_stream(grpc_chttp2_transport *t,
                                                grpc_chttp2_stream *s) {
-  bool ret = stream_list_maybe_remove(t, s, GRPC_CHTTP2_LIST_STALLED_BY_STREAM);
-  GRPC_FLOW_CONTROL_IF_TRACING(
-      if (ret) gpr_log(GPR_DEBUG, "stream %u un-stalled by stream", s->id));
-  return ret;
+  return stream_list_maybe_remove(t, s, GRPC_CHTTP2_LIST_STALLED_BY_STREAM);
 }
diff --git a/src/core/ext/transport/chttp2/transport/writing.c b/src/core/ext/transport/chttp2/transport/writing.c
index 3ded801985..7d9d4867e1 100644
--- a/src/core/ext/transport/chttp2/transport/writing.c
+++ b/src/core/ext/transport/chttp2/transport/writing.c
@@ -68,7 +68,7 @@ static void maybe_initiate_ping(grpc_exec_ctx *exec_ctx,
   }
   if (t->ping_state.pings_before_data_required == 0 &&
       t->ping_policy.max_pings_without_data != 0) {
-    /* need to send something of substance before sending a ping again */
+    /* need to receive something of substance before sending a ping again */
     if (GRPC_TRACER_ON(grpc_http_trace) ||
         GRPC_TRACER_ON(grpc_bdp_estimator_trace)) {
       gpr_log(GPR_DEBUG, "Ping delayed [%p]: too many recent pings: %d/%d",
@@ -78,11 +78,18 @@ static void maybe_initiate_ping(grpc_exec_ctx *exec_ctx,
     return;
   }
   gpr_timespec now = gpr_now(GPR_CLOCK_MONOTONIC);
-  gpr_timespec elapsed = gpr_time_sub(now, t->ping_state.last_ping_sent_time);
-  /*gpr_log(GPR_DEBUG, "elapsed:%d.%09d min:%d.%09d", (int)elapsed.tv_sec,
-          elapsed.tv_nsec, (int)t->ping_policy.min_time_between_pings.tv_sec,
-          (int)t->ping_policy.min_time_between_pings.tv_nsec);*/
-  if (gpr_time_cmp(elapsed, t->ping_policy.min_time_between_pings) < 0) {
+  gpr_timespec next_allowed_ping =
+      gpr_time_add(t->ping_state.last_ping_sent_time,
+                   t->ping_policy.min_sent_ping_interval_without_data);
+  if (t->keepalive_permit_without_calls == 0 &&
+      grpc_chttp2_stream_map_size(&t->stream_map) == 0) {
+    next_allowed_ping = gpr_time_add(t->ping_recv_state.last_ping_recv_time,
+                                     gpr_time_from_seconds(7200, GPR_TIMESPAN));
+  }
+  /* gpr_log(GPR_DEBUG, "next_allowed_ping:%d.%09d now:%d.%09d",
+          (int)next_allowed_ping.tv_sec, (int)next_allowed_ping.tv_nsec,
+          (int)now.tv_sec, (int)now.tv_nsec); */
+  if (gpr_time_cmp(next_allowed_ping, now) > 0) {
     /* not enough elapsed time between successive pings */
     if (GRPC_TRACER_ON(grpc_http_trace) ||
         GRPC_TRACER_ON(grpc_bdp_estimator_trace)) {
@@ -93,9 +100,7 @@ static void maybe_initiate_ping(grpc_exec_ctx *exec_ctx,
     if (!t->ping_state.is_delayed_ping_timer_set) {
       t->ping_state.is_delayed_ping_timer_set = true;
       grpc_timer_init(exec_ctx, &t->ping_state.delayed_ping_timer,
-                      gpr_time_add(t->ping_state.last_ping_sent_time,
-                                   t->ping_policy.min_time_between_pings),
-                      &t->retry_initiate_ping_locked,
+                      next_allowed_ping, &t->retry_initiate_ping_locked,
                       gpr_now(GPR_CLOCK_MONOTONIC));
     }
     return;
@@ -119,6 +124,12 @@ static void maybe_initiate_ping(grpc_exec_ctx *exec_ctx,
                         grpc_chttp2_ping_create(false, pq->inflight_id));
   GRPC_STATS_INC_HTTP2_PINGS_SENT(exec_ctx);
   t->ping_state.last_ping_sent_time = now;
+  if (GRPC_TRACER_ON(grpc_http_trace) ||
+      GRPC_TRACER_ON(grpc_bdp_estimator_trace)) {
+    gpr_log(GPR_DEBUG, "Ping sent [%p]: %d/%d", t->peer_string,
+            t->ping_state.pings_before_data_required,
+            t->ping_policy.max_pings_without_data);
+  }
   t->ping_state.pings_before_data_required -=
       (t->ping_state.pings_before_data_required != 0);
 }
@@ -257,8 +268,7 @@ grpc_chttp2_begin_write_result grpc_chttp2_begin_write(
             .stats = &s->stats.outgoing};
         grpc_chttp2_encode_header(exec_ctx, &t->hpack_compressor, NULL, 0,
                                   s->send_initial_metadata, &hopt, &t->outbuf);
-        t->ping_state.pings_before_data_required =
-            t->ping_policy.max_pings_without_data;
+        now_writing = true;
         if (!t->is_client) {
           t->ping_recv_state.last_ping_recv_time =
               gpr_inf_past(GPR_CLOCK_MONOTONIC);
@@ -297,8 +307,6 @@ grpc_chttp2_begin_write_result grpc_chttp2_begin_write(
       grpc_slice_buffer_add(
           &t->outbuf, grpc_chttp2_window_update_create(s->id, stream_announce,
                                                        &s->stats.outgoing));
-      t->ping_state.pings_before_data_required =
-          t->ping_policy.max_pings_without_data;
       if (!t->is_client) {
         t->ping_recv_state.last_ping_recv_time =
             gpr_inf_past(GPR_CLOCK_MONOTONIC);
@@ -375,8 +383,6 @@ grpc_chttp2_begin_write_result grpc_chttp2_begin_write(
                                           send_bytes);
             s->sending_bytes += send_bytes;
           }
-          t->ping_state.pings_before_data_required =
-              t->ping_policy.max_pings_without_data;
           if (!t->is_client) {
             t->ping_recv_state.last_ping_recv_time =
                 gpr_inf_past(GPR_CLOCK_MONOTONIC);
@@ -487,8 +493,6 @@ grpc_chttp2_begin_write_result grpc_chttp2_begin_write(
     grpc_slice_buffer_add(
         &t->outbuf, grpc_chttp2_window_update_create(0, transport_announce,
                                                      &throwaway_stats));
-    t->ping_state.pings_before_data_required =
-        t->ping_policy.max_pings_without_data;
     if (!t->is_client) {
       t->ping_recv_state.last_ping_recv_time =
           gpr_inf_past(GPR_CLOCK_MONOTONIC);
diff --git a/src/core/lib/http/httpcli_security_connector.c b/src/core/lib/http/httpcli_security_connector.c
index 97c2886525..c553fa3981 100644
--- a/src/core/lib/http/httpcli_security_connector.c
+++ b/src/core/lib/http/httpcli_security_connector.c
@@ -43,7 +43,8 @@ static void httpcli_ssl_destroy(grpc_exec_ctx *exec_ctx,
   grpc_httpcli_ssl_channel_security_connector *c =
       (grpc_httpcli_ssl_channel_security_connector *)sc;
   if (c->handshaker_factory != NULL) {
-    tsi_ssl_client_handshaker_factory_destroy(c->handshaker_factory);
+    tsi_ssl_client_handshaker_factory_unref(c->handshaker_factory);
+    c->handshaker_factory = NULL;
   }
   if (c->secure_peer_name != NULL) gpr_free(c->secure_peer_name);
   gpr_free(sc);
diff --git a/src/core/lib/iomgr/closure.c b/src/core/lib/iomgr/closure.c
index 7236e23cf7..00edefc6ae 100644
--- a/src/core/lib/iomgr/closure.c
+++ b/src/core/lib/iomgr/closure.c
@@ -167,7 +167,14 @@ void grpc_closure_sched(grpc_exec_ctx *exec_ctx, grpc_closure *c,
   GPR_TIMER_BEGIN("grpc_closure_sched", 0);
   if (c != NULL) {
 #ifndef NDEBUG
-    GPR_ASSERT(!c->scheduled);
+    if (c->scheduled) {
+      gpr_log(GPR_ERROR,
+              "Closure already scheduled. (closure: %p, created: [%s:%d], "
+              "previously scheduled at: [%s: %d] run?: %s",
+              c, c->file_created, c->line_created, c->file_initiated,
+              c->line_initiated, c->run ? "true" : "false");
+      abort();
+    }
     c->scheduled = true;
     c->file_initiated = file;
     c->line_initiated = line;
@@ -191,7 +198,14 @@ void grpc_closure_list_sched(grpc_exec_ctx *exec_ctx, grpc_closure_list *list) {
   while (c != NULL) {
     grpc_closure *next = c->next_data.next;
 #ifndef NDEBUG
-    GPR_ASSERT(!c->scheduled);
+    if (c->scheduled) {
+      gpr_log(GPR_ERROR,
+              "Closure already scheduled. (closure: %p, created: [%s:%d], "
+              "previously scheduled at: [%s: %d] run?: %s",
+              c, c->file_created, c->line_created, c->file_initiated,
+              c->line_initiated, c->run ? "true" : "false");
+      abort();
+    }
     c->scheduled = true;
     c->file_initiated = file;
     c->line_initiated = line;
diff --git a/src/core/lib/security/transport/security_connector.c b/src/core/lib/security/transport/security_connector.c
index a7568b995f..2a9e939d40 100644
--- a/src/core/lib/security/transport/security_connector.c
+++ b/src/core/lib/security/transport/security_connector.c
@@ -455,14 +455,14 @@ grpc_server_security_connector *grpc_fake_server_security_connector_create(
 
 typedef struct {
   grpc_channel_security_connector base;
-  tsi_ssl_client_handshaker_factory *handshaker_factory;
+  tsi_ssl_client_handshaker_factory *client_handshaker_factory;
   char *target_name;
   char *overridden_target_name;
 } grpc_ssl_channel_security_connector;
 
 typedef struct {
   grpc_server_security_connector base;
-  tsi_ssl_server_handshaker_factory *handshaker_factory;
+  tsi_ssl_server_handshaker_factory *server_handshaker_factory;
 } grpc_ssl_server_security_connector;
 
 static void ssl_channel_destroy(grpc_exec_ctx *exec_ctx,
@@ -470,9 +470,8 @@ static void ssl_channel_destroy(grpc_exec_ctx *exec_ctx,
   grpc_ssl_channel_security_connector *c =
       (grpc_ssl_channel_security_connector *)sc;
   grpc_call_credentials_unref(exec_ctx, c->base.request_metadata_creds);
-  if (c->handshaker_factory != NULL) {
-    tsi_ssl_client_handshaker_factory_destroy(c->handshaker_factory);
-  }
+  tsi_ssl_client_handshaker_factory_unref(c->client_handshaker_factory);
+  c->client_handshaker_factory = NULL;
   if (c->target_name != NULL) gpr_free(c->target_name);
   if (c->overridden_target_name != NULL) gpr_free(c->overridden_target_name);
   gpr_free(sc);
@@ -482,9 +481,8 @@ 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) {
-    tsi_ssl_server_handshaker_factory_destroy(c->handshaker_factory);
-  }
+  tsi_ssl_server_handshaker_factory_unref(c->server_handshaker_factory);
+  c->server_handshaker_factory = NULL;
   gpr_free(sc);
 }
 
@@ -496,7 +494,7 @@ static void ssl_channel_add_handshakers(grpc_exec_ctx *exec_ctx,
   // Instantiate TSI handshaker.
   tsi_handshaker *tsi_hs = NULL;
   tsi_result result = tsi_ssl_client_handshaker_factory_create_handshaker(
-      c->handshaker_factory,
+      c->client_handshaker_factory,
       c->overridden_target_name != NULL ? c->overridden_target_name
                                         : c->target_name,
       &tsi_hs);
@@ -521,7 +519,7 @@ static void ssl_server_add_handshakers(grpc_exec_ctx *exec_ctx,
   // Instantiate TSI handshaker.
   tsi_handshaker *tsi_hs = NULL;
   tsi_result result = tsi_ssl_server_handshaker_factory_create_handshaker(
-      c->handshaker_factory, &tsi_hs);
+      c->server_handshaker_factory, &tsi_hs);
   if (result != TSI_OK) {
     gpr_log(GPR_ERROR, "Handshaker creation failed with error %s.",
             tsi_result_to_string(result));
@@ -852,7 +850,7 @@ grpc_security_status grpc_ssl_channel_security_connector_create(
   result = tsi_create_ssl_client_handshaker_factory(
       has_key_cert_pair ? &config->pem_key_cert_pair : NULL, pem_root_certs,
       ssl_cipher_suites(), alpn_protocol_strings, (uint16_t)num_alpn_protocols,
-      &c->handshaker_factory);
+      &c->client_handshaker_factory);
   if (result != TSI_OK) {
     gpr_log(GPR_ERROR, "Handshaker factory creation failed with %s.",
             tsi_result_to_string(result));
@@ -897,7 +895,7 @@ grpc_security_status grpc_ssl_server_security_connector_create(
       config->pem_root_certs, get_tsi_client_certificate_request_type(
                                   config->client_certificate_request),
       ssl_cipher_suites(), alpn_protocol_strings, (uint16_t)num_alpn_protocols,
-      &c->handshaker_factory);
+      &c->server_handshaker_factory);
   if (result != TSI_OK) {
     gpr_log(GPR_ERROR, "Handshaker factory creation failed with %s.",
             tsi_result_to_string(result));
diff --git a/src/core/tsi/ssl_transport_security.c b/src/core/tsi/ssl_transport_security.c
index 1fd65928f9..7ebf9dd96f 100644
--- a/src/core/tsi/ssl_transport_security.c
+++ b/src/core/tsi/ssl_transport_security.c
@@ -67,7 +67,13 @@
 
 /* --- Structure definitions. ---*/
 
+struct tsi_ssl_handshaker_factory {
+  const tsi_ssl_handshaker_factory_vtable *vtable;
+  gpr_refcount refcount;
+};
+
 struct tsi_ssl_client_handshaker_factory {
+  tsi_ssl_handshaker_factory base;
   SSL_CTX *ssl_context;
   unsigned char *alpn_protocol_list;
   size_t alpn_protocol_list_length;
@@ -77,6 +83,7 @@ struct tsi_ssl_server_handshaker_factory {
   /* Several contexts to support SNI.
      The tsi_peer array contains the subject names of the server certificates
      associated with the contexts at the same index.  */
+  tsi_ssl_handshaker_factory base;
   SSL_CTX **ssl_contexts;
   tsi_peer *ssl_context_x509_subject_names;
   size_t ssl_context_count;
@@ -90,6 +97,7 @@ typedef struct {
   BIO *into_ssl;
   BIO *from_ssl;
   tsi_result result;
+  tsi_ssl_handshaker_factory *factory_ref;
 } tsi_ssl_handshaker;
 
 typedef struct {
@@ -846,6 +854,47 @@ static const tsi_frame_protector_vtable frame_protector_vtable = {
     ssl_protector_destroy,
 };
 
+/* --- tsi_server_handshaker_factory methods implementation. --- */
+
+static void tsi_ssl_handshaker_factory_destroy(
+    tsi_ssl_handshaker_factory *self) {
+  if (self == NULL) return;
+
+  if (self->vtable != NULL && self->vtable->destroy != NULL) {
+    self->vtable->destroy(self);
+  }
+  /* Note, we don't free(self) here because this object is always directly
+   * embedded in another object. If tsi_ssl_handshaker_factory_init allocates
+   * any memory, it should be free'd here. */
+}
+
+static tsi_ssl_handshaker_factory *tsi_ssl_handshaker_factory_ref(
+    tsi_ssl_handshaker_factory *self) {
+  if (self == NULL) return NULL;
+  gpr_refn(&self->refcount, 1);
+  return self;
+}
+
+static void tsi_ssl_handshaker_factory_unref(tsi_ssl_handshaker_factory *self) {
+  if (self == NULL) return;
+
+  if (gpr_unref(&self->refcount)) {
+    tsi_ssl_handshaker_factory_destroy(self);
+  }
+}
+
+static tsi_ssl_handshaker_factory_vtable handshaker_factory_vtable = {NULL};
+
+/* Initializes a tsi_ssl_handshaker_factory object. Caller is responsible for
+ * allocating memory for the factory. */
+static void tsi_ssl_handshaker_factory_init(
+    tsi_ssl_handshaker_factory *factory) {
+  GPR_ASSERT(factory != NULL);
+
+  factory->vtable = &handshaker_factory_vtable;
+  gpr_ref_init(&factory->refcount, 1);
+}
+
 /* --- tsi_handshaker methods implementation. ---*/
 
 static tsi_result ssl_handshaker_get_bytes_to_send_to_peer(tsi_handshaker *self,
@@ -1013,6 +1062,7 @@ static tsi_result ssl_handshaker_create_frame_protector(
 static void ssl_handshaker_destroy(tsi_handshaker *self) {
   tsi_ssl_handshaker *impl = (tsi_ssl_handshaker *)self;
   SSL_free(impl->ssl); /* The BIO objects are owned by ssl */
+  tsi_ssl_handshaker_factory_unref(impl->factory_ref);
   gpr_free(impl);
 }
 
@@ -1030,6 +1080,7 @@ static const tsi_handshaker_vtable handshaker_vtable = {
 
 static tsi_result create_tsi_ssl_handshaker(SSL_CTX *ctx, int is_client,
                                             const char *server_name_indication,
+                                            tsi_ssl_handshaker_factory *factory,
                                             tsi_handshaker **handshaker) {
   SSL *ssl = SSL_new(ctx);
   BIO *into_ssl = NULL;
@@ -1085,6 +1136,8 @@ static tsi_result create_tsi_ssl_handshaker(SSL_CTX *ctx, int is_client,
   impl->from_ssl = from_ssl;
   impl->result = TSI_HANDSHAKE_IN_PROGRESS;
   impl->base.vtable = &handshaker_vtable;
+  impl->factory_ref = tsi_ssl_handshaker_factory_ref(factory);
+
   *handshaker = &impl->base;
   return TSI_OK;
 }
@@ -1121,11 +1174,20 @@ tsi_result tsi_ssl_client_handshaker_factory_create_handshaker(
     tsi_ssl_client_handshaker_factory *self, const char *server_name_indication,
     tsi_handshaker **handshaker) {
   return create_tsi_ssl_handshaker(self->ssl_context, 1, server_name_indication,
-                                   handshaker);
+                                   &self->base, handshaker);
 }
 
-void tsi_ssl_client_handshaker_factory_destroy(
+void tsi_ssl_client_handshaker_factory_unref(
     tsi_ssl_client_handshaker_factory *self) {
+  if (self == NULL) return;
+  tsi_ssl_handshaker_factory_unref(&self->base);
+}
+
+static void tsi_ssl_client_handshaker_factory_destroy(
+    tsi_ssl_handshaker_factory *factory) {
+  if (factory == NULL) return;
+  tsi_ssl_client_handshaker_factory *self =
+      (tsi_ssl_client_handshaker_factory *)factory;
   if (self->ssl_context != NULL) SSL_CTX_free(self->ssl_context);
   if (self->alpn_protocol_list != NULL) gpr_free(self->alpn_protocol_list);
   gpr_free(self);
@@ -1150,11 +1212,21 @@ tsi_result tsi_ssl_server_handshaker_factory_create_handshaker(
   if (self->ssl_context_count == 0) return TSI_INVALID_ARGUMENT;
   /* Create the handshaker with the first context. We will switch if needed
      because of SNI in ssl_server_handshaker_factory_servername_callback.  */
-  return create_tsi_ssl_handshaker(self->ssl_contexts[0], 0, NULL, handshaker);
+  return create_tsi_ssl_handshaker(self->ssl_contexts[0], 0, NULL, &self->base,
+                                   handshaker);
 }
 
-void tsi_ssl_server_handshaker_factory_destroy(
+void tsi_ssl_server_handshaker_factory_unref(
     tsi_ssl_server_handshaker_factory *self) {
+  if (self == NULL) return;
+  tsi_ssl_handshaker_factory_unref(&self->base);
+}
+
+static void tsi_ssl_server_handshaker_factory_destroy(
+    tsi_ssl_handshaker_factory *factory) {
+  if (factory == NULL) return;
+  tsi_ssl_server_handshaker_factory *self =
+      (tsi_ssl_server_handshaker_factory *)factory;
   size_t i;
   for (i = 0; i < self->ssl_context_count; i++) {
     if (self->ssl_contexts[i] != NULL) {
@@ -1263,6 +1335,9 @@ static int server_handshaker_factory_npn_advertised_callback(
 
 /* --- tsi_ssl_handshaker_factory constructors. --- */
 
+static tsi_ssl_handshaker_factory_vtable client_handshaker_factory_vtable = {
+    tsi_ssl_client_handshaker_factory_destroy};
+
 tsi_result tsi_create_ssl_client_handshaker_factory(
     const tsi_ssl_pem_key_cert_pair *pem_key_cert_pair,
     const char *pem_root_certs, const char *cipher_suites,
@@ -1285,6 +1360,9 @@ tsi_result tsi_create_ssl_client_handshaker_factory(
   }
 
   impl = gpr_zalloc(sizeof(*impl));
+  tsi_ssl_handshaker_factory_init(&impl->base);
+  impl->base.vtable = &client_handshaker_factory_vtable;
+
   impl->ssl_context = ssl_context;
 
   do {
@@ -1322,7 +1400,7 @@ tsi_result tsi_create_ssl_client_handshaker_factory(
     }
   } while (0);
   if (result != TSI_OK) {
-    tsi_ssl_client_handshaker_factory_destroy(impl);
+    tsi_ssl_handshaker_factory_unref(&impl->base);
     return result;
   }
   SSL_CTX_set_verify(ssl_context, SSL_VERIFY_PEER, NULL);
@@ -1332,6 +1410,9 @@ tsi_result tsi_create_ssl_client_handshaker_factory(
   return TSI_OK;
 }
 
+static tsi_ssl_handshaker_factory_vtable server_handshaker_factory_vtable = {
+    tsi_ssl_server_handshaker_factory_destroy};
+
 tsi_result tsi_create_ssl_server_handshaker_factory(
     const tsi_ssl_pem_key_cert_pair *pem_key_cert_pairs,
     size_t num_key_cert_pairs, const char *pem_client_root_certs,
@@ -1364,12 +1445,15 @@ tsi_result tsi_create_ssl_server_handshaker_factory_ex(
   }
 
   impl = gpr_zalloc(sizeof(*impl));
+  tsi_ssl_handshaker_factory_init(&impl->base);
+  impl->base.vtable = &server_handshaker_factory_vtable;
+
   impl->ssl_contexts = gpr_zalloc(num_key_cert_pairs * sizeof(SSL_CTX *));
   impl->ssl_context_x509_subject_names =
       gpr_zalloc(num_key_cert_pairs * sizeof(tsi_peer));
   if (impl->ssl_contexts == NULL ||
       impl->ssl_context_x509_subject_names == NULL) {
-    tsi_ssl_server_handshaker_factory_destroy(impl);
+    tsi_ssl_handshaker_factory_unref(&impl->base);
     return TSI_OUT_OF_RESOURCES;
   }
   impl->ssl_context_count = num_key_cert_pairs;
@@ -1379,7 +1463,7 @@ tsi_result tsi_create_ssl_server_handshaker_factory_ex(
                                            &impl->alpn_protocol_list,
                                            &impl->alpn_protocol_list_length);
     if (result != TSI_OK) {
-      tsi_ssl_server_handshaker_factory_destroy(impl);
+      tsi_ssl_handshaker_factory_unref(&impl->base);
       return result;
     }
   }
@@ -1451,10 +1535,11 @@ tsi_result tsi_create_ssl_server_handshaker_factory_ex(
     } while (0);
 
     if (result != TSI_OK) {
-      tsi_ssl_server_handshaker_factory_destroy(impl);
+      tsi_ssl_handshaker_factory_unref(&impl->base);
       return result;
     }
   }
+
   *factory = impl;
   return TSI_OK;
 }
@@ -1501,3 +1586,15 @@ int tsi_ssl_peer_matches_name(const tsi_peer *peer, const char *name) {
 
   return 0; /* Not found. */
 }
+
+/* --- Testing support. --- */
+const tsi_ssl_handshaker_factory_vtable *tsi_ssl_handshaker_factory_swap_vtable(
+    tsi_ssl_handshaker_factory *factory,
+    tsi_ssl_handshaker_factory_vtable *new_vtable) {
+  GPR_ASSERT(factory != NULL);
+  GPR_ASSERT(factory->vtable != NULL);
+
+  const tsi_ssl_handshaker_factory_vtable *orig_vtable = factory->vtable;
+  factory->vtable = new_vtable;
+  return orig_vtable;
+}
diff --git a/src/core/tsi/ssl_transport_security.h b/src/core/tsi/ssl_transport_security.h
index 177599930b..3abfdf5ed8 100644
--- a/src/core/tsi/ssl_transport_security.h
+++ b/src/core/tsi/ssl_transport_security.h
@@ -96,10 +96,10 @@ tsi_result tsi_ssl_client_handshaker_factory_create_handshaker(
     tsi_ssl_client_handshaker_factory *self, const char *server_name_indication,
     tsi_handshaker **handshaker);
 
-/* Destroys the handshaker factory. WARNING: it is unsafe to destroy a factory
-   while handshakers created with this factory are still in use.  */
-void tsi_ssl_client_handshaker_factory_destroy(
-    tsi_ssl_client_handshaker_factory *self);
+/* Decrements reference count of the handshaker factory. Handshaker factory will
+ * be destroyed once no references exist. */
+void tsi_ssl_client_handshaker_factory_unref(
+    tsi_ssl_client_handshaker_factory *factory);
 
 /* --- tsi_ssl_server_handshaker_factory object ---
 
@@ -158,9 +158,9 @@ tsi_result tsi_create_ssl_server_handshaker_factory_ex(
 tsi_result tsi_ssl_server_handshaker_factory_create_handshaker(
     tsi_ssl_server_handshaker_factory *self, tsi_handshaker **handshaker);
 
-/* Destroys the handshaker factory. WARNING: it is unsafe to destroy a factory
-   while handshakers created with this factory are still in use.  */
-void tsi_ssl_server_handshaker_factory_destroy(
+/* Decrements reference count of the handshaker factory. Handshaker factory will
+ * be destroyed once no references exist. */
+void tsi_ssl_server_handshaker_factory_unref(
     tsi_ssl_server_handshaker_factory *self);
 
 /* Util that checks that an ssl peer matches a specific name.
@@ -170,6 +170,29 @@ void tsi_ssl_server_handshaker_factory_destroy(
    - handle public suffix wildchar more strictly (e.g. *.co.uk) */
 int tsi_ssl_peer_matches_name(const tsi_peer *peer, const char *name);
 
+/* --- Testing support. ---
+
+   These functions and typedefs are not intended to be used outside of testing.
+   */
+
+/* Base type of client and server handshaker factories. */
+typedef struct tsi_ssl_handshaker_factory tsi_ssl_handshaker_factory;
+
+/* Function pointer to handshaker_factory destructor. */
+typedef void (*tsi_ssl_handshaker_factory_destructor)(
+    tsi_ssl_handshaker_factory *factory);
+
+/* Virtual table for tsi_ssl_handshaker_factory. */
+typedef struct {
+  tsi_ssl_handshaker_factory_destructor destroy;
+} tsi_ssl_handshaker_factory_vtable;
+
+/* Set destructor of handshaker_factory to new_destructor, returns previous
+   destructor. */
+const tsi_ssl_handshaker_factory_vtable *tsi_ssl_handshaker_factory_swap_vtable(
+    tsi_ssl_handshaker_factory *factory,
+    tsi_ssl_handshaker_factory_vtable *new_vtable);
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/src/csharp/Grpc.Auth/Grpc.Auth.csproj b/src/csharp/Grpc.Auth/Grpc.Auth.csproj
index abf326459c..bbcbd95be5 100755
--- a/src/csharp/Grpc.Auth/Grpc.Auth.csproj
+++ b/src/csharp/Grpc.Auth/Grpc.Auth.csproj
@@ -15,7 +15,6 @@
     <PackageTags>gRPC RPC Protocol HTTP/2 Auth OAuth2</PackageTags>
     <PackageProjectUrl>https://github.com/grpc/grpc</PackageProjectUrl>
     <PackageLicenseUrl>https://github.com/grpc/grpc/blob/master/LICENSE</PackageLicenseUrl>
-    <NetStandardImplicitPackageVersion Condition=" '$(TargetFramework)' == 'netstandard1.5' ">1.6.0</NetStandardImplicitPackageVersion>
     <IncludeSymbols>true</IncludeSymbols>
     <IncludeSource>true</IncludeSource>
     <GenerateDocumentationFile>true</GenerateDocumentationFile>
diff --git a/src/csharp/Grpc.Core.Testing/Grpc.Core.Testing.csproj b/src/csharp/Grpc.Core.Testing/Grpc.Core.Testing.csproj
index 9ad6fd0c61..4d6767fa98 100755
--- a/src/csharp/Grpc.Core.Testing/Grpc.Core.Testing.csproj
+++ b/src/csharp/Grpc.Core.Testing/Grpc.Core.Testing.csproj
@@ -15,7 +15,6 @@
     <PackageTags>gRPC test testing</PackageTags>
     <PackageProjectUrl>https://github.com/grpc/grpc</PackageProjectUrl>
     <PackageLicenseUrl>https://github.com/grpc/grpc/blob/master/LICENSE</PackageLicenseUrl>
-    <NetStandardImplicitPackageVersion Condition=" '$(TargetFramework)' == 'netstandard1.5' ">1.6.0</NetStandardImplicitPackageVersion>
     <IncludeSymbols>true</IncludeSymbols>
     <IncludeSource>true</IncludeSource>
     <GenerateDocumentationFile>true</GenerateDocumentationFile>
diff --git a/src/csharp/Grpc.Core.Tests/Grpc.Core.Tests.csproj b/src/csharp/Grpc.Core.Tests/Grpc.Core.Tests.csproj
index 6df68fda58..18993a93e0 100755
--- a/src/csharp/Grpc.Core.Tests/Grpc.Core.Tests.csproj
+++ b/src/csharp/Grpc.Core.Tests/Grpc.Core.Tests.csproj
@@ -8,8 +8,6 @@
     <AssemblyName>Grpc.Core.Tests</AssemblyName>
     <OutputType>Exe</OutputType>
     <PackageId>Grpc.Core.Tests</PackageId>
-    <PackageTargetFallback Condition=" '$(TargetFramework)' == 'netcoreapp1.0' ">$(PackageTargetFallback);portable-net45</PackageTargetFallback>
-    <RuntimeFrameworkVersion Condition=" '$(TargetFramework)' == 'netcoreapp1.0' ">1.0.4</RuntimeFrameworkVersion>
     <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
   </PropertyGroup>
 
@@ -21,7 +19,6 @@
     <PackageReference Include="Newtonsoft.Json" Version="9.0.1" />
     <PackageReference Include="NUnit" Version="3.6.0" />
     <PackageReference Include="NUnitLite" Version="3.6.0" />
-    <PackageReference Include="NUnit.ConsoleRunner" Version="3.6.0" />
     <PackageReference Include="OpenCover" Version="4.6.519" />
     <PackageReference Include="ReportGenerator" Version="2.4.4.0" />
   </ItemGroup>
diff --git a/src/csharp/Grpc.Core/Grpc.Core.csproj b/src/csharp/Grpc.Core/Grpc.Core.csproj
index dde800aadd..d9950b2f20 100755
--- a/src/csharp/Grpc.Core/Grpc.Core.csproj
+++ b/src/csharp/Grpc.Core/Grpc.Core.csproj
@@ -14,7 +14,6 @@
     <PackageTags>gRPC RPC Protocol HTTP/2</PackageTags>
     <PackageProjectUrl>https://github.com/grpc/grpc</PackageProjectUrl>
     <PackageLicenseUrl>https://github.com/grpc/grpc/blob/master/LICENSE</PackageLicenseUrl>
-    <NetStandardImplicitPackageVersion Condition=" '$(TargetFramework)' == 'netstandard1.5' ">1.6.0</NetStandardImplicitPackageVersion>
     <IncludeSymbols>true</IncludeSymbols>
     <IncludeSource>true</IncludeSource>
     <GenerateDocumentationFile>true</GenerateDocumentationFile>
@@ -65,7 +64,7 @@
   <ItemGroup Condition=" '$(TargetFramework)' == 'netstandard1.5' ">
     <PackageReference Include="System.Runtime.Loader" Version="4.0.0" />
     <PackageReference Include="System.Threading.Thread" Version="4.0.0" />
-    <PackageReference Include="System.Threading.ThreadPool" Version="4.0.0" />
+    <PackageReference Include="System.Threading.ThreadPool" Version="4.0.10" />
   </ItemGroup>
 
   <Import Project="NativeDeps.csproj.include" />
diff --git a/src/csharp/Grpc.Examples.MathClient/Grpc.Examples.MathClient.csproj b/src/csharp/Grpc.Examples.MathClient/Grpc.Examples.MathClient.csproj
index 74deed6584..db4e3ef4e3 100755
--- a/src/csharp/Grpc.Examples.MathClient/Grpc.Examples.MathClient.csproj
+++ b/src/csharp/Grpc.Examples.MathClient/Grpc.Examples.MathClient.csproj
@@ -8,7 +8,6 @@
     <AssemblyName>Grpc.Examples.MathClient</AssemblyName>
     <OutputType>Exe</OutputType>
     <PackageId>Grpc.Examples.MathClient</PackageId>
-    <RuntimeFrameworkVersion Condition=" '$(TargetFramework)' == 'netcoreapp1.0' ">1.0.4</RuntimeFrameworkVersion>
     <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
   </PropertyGroup>
 
diff --git a/src/csharp/Grpc.Examples.MathServer/Grpc.Examples.MathServer.csproj b/src/csharp/Grpc.Examples.MathServer/Grpc.Examples.MathServer.csproj
index 1abf261498..b12b418d01 100755
--- a/src/csharp/Grpc.Examples.MathServer/Grpc.Examples.MathServer.csproj
+++ b/src/csharp/Grpc.Examples.MathServer/Grpc.Examples.MathServer.csproj
@@ -8,7 +8,6 @@
     <AssemblyName>Grpc.Examples.MathServer</AssemblyName>
     <OutputType>Exe</OutputType>
     <PackageId>Grpc.Examples.MathServer</PackageId>
-    <RuntimeFrameworkVersion Condition=" '$(TargetFramework)' == 'netcoreapp1.0' ">1.0.4</RuntimeFrameworkVersion>
     <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
   </PropertyGroup>
 
diff --git a/src/csharp/Grpc.Examples.Tests/Grpc.Examples.Tests.csproj b/src/csharp/Grpc.Examples.Tests/Grpc.Examples.Tests.csproj
index d2a13ed6e1..3ccc9adfaf 100755
--- a/src/csharp/Grpc.Examples.Tests/Grpc.Examples.Tests.csproj
+++ b/src/csharp/Grpc.Examples.Tests/Grpc.Examples.Tests.csproj
@@ -8,8 +8,6 @@
     <AssemblyName>Grpc.Examples.Tests</AssemblyName>
     <OutputType>Exe</OutputType>
     <PackageId>Grpc.Examples.Tests</PackageId>
-    <PackageTargetFallback Condition=" '$(TargetFramework)' == 'netcoreapp1.0' ">$(PackageTargetFallback);portable-net45</PackageTargetFallback>
-    <RuntimeFrameworkVersion Condition=" '$(TargetFramework)' == 'netcoreapp1.0' ">1.0.4</RuntimeFrameworkVersion>
     <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
   </PropertyGroup>
 
diff --git a/src/csharp/Grpc.Examples/Grpc.Examples.csproj b/src/csharp/Grpc.Examples/Grpc.Examples.csproj
index 491d313f17..baa3b4ce6c 100755
--- a/src/csharp/Grpc.Examples/Grpc.Examples.csproj
+++ b/src/csharp/Grpc.Examples/Grpc.Examples.csproj
@@ -7,7 +7,6 @@
     <TargetFrameworks>net45;netcoreapp1.0</TargetFrameworks>
     <AssemblyName>Grpc.Examples</AssemblyName>
     <PackageId>Grpc.Examples</PackageId>
-    <RuntimeFrameworkVersion Condition=" '$(TargetFramework)' == 'netcoreapp1.0' ">1.0.4</RuntimeFrameworkVersion>
     <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
   </PropertyGroup>
 
diff --git a/src/csharp/Grpc.HealthCheck.Tests/Grpc.HealthCheck.Tests.csproj b/src/csharp/Grpc.HealthCheck.Tests/Grpc.HealthCheck.Tests.csproj
index 2ccf46b9b9..9da0539dcb 100755
--- a/src/csharp/Grpc.HealthCheck.Tests/Grpc.HealthCheck.Tests.csproj
+++ b/src/csharp/Grpc.HealthCheck.Tests/Grpc.HealthCheck.Tests.csproj
@@ -8,8 +8,6 @@
     <AssemblyName>Grpc.HealthCheck.Tests</AssemblyName>
     <OutputType>Exe</OutputType>
     <PackageId>Grpc.HealthCheck.Tests</PackageId>
-    <PackageTargetFallback Condition=" '$(TargetFramework)' == 'netcoreapp1.0' ">$(PackageTargetFallback);portable-net45</PackageTargetFallback>
-    <RuntimeFrameworkVersion Condition=" '$(TargetFramework)' == 'netcoreapp1.0' ">1.0.4</RuntimeFrameworkVersion>
     <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
   </PropertyGroup>
 
diff --git a/src/csharp/Grpc.HealthCheck/Grpc.HealthCheck.csproj b/src/csharp/Grpc.HealthCheck/Grpc.HealthCheck.csproj
index 3eb90434f3..681719d124 100755
--- a/src/csharp/Grpc.HealthCheck/Grpc.HealthCheck.csproj
+++ b/src/csharp/Grpc.HealthCheck/Grpc.HealthCheck.csproj
@@ -14,7 +14,6 @@
     <PackageTags>gRPC health check</PackageTags>
     <PackageProjectUrl>https://github.com/grpc/grpc</PackageProjectUrl>
     <PackageLicenseUrl>https://github.com/grpc/grpc/blob/master/LICENSE</PackageLicenseUrl>
-    <NetStandardImplicitPackageVersion Condition=" '$(TargetFramework)' == 'netstandard1.5' ">1.6.0</NetStandardImplicitPackageVersion>
     <IncludeSymbols>true</IncludeSymbols>
     <IncludeSource>true</IncludeSource>
     <GenerateDocumentationFile>true</GenerateDocumentationFile>
diff --git a/src/csharp/Grpc.IntegrationTesting.Client/Grpc.IntegrationTesting.Client.csproj b/src/csharp/Grpc.IntegrationTesting.Client/Grpc.IntegrationTesting.Client.csproj
index c67beea7cd..35713156ea 100755
--- a/src/csharp/Grpc.IntegrationTesting.Client/Grpc.IntegrationTesting.Client.csproj
+++ b/src/csharp/Grpc.IntegrationTesting.Client/Grpc.IntegrationTesting.Client.csproj
@@ -8,8 +8,6 @@
     <AssemblyName>Grpc.IntegrationTesting.Client</AssemblyName>
     <OutputType>Exe</OutputType>
     <PackageId>Grpc.IntegrationTesting.Client</PackageId>
-    <PackageTargetFallback Condition=" '$(TargetFramework)' == 'netcoreapp1.0' ">$(PackageTargetFallback);portable-net45</PackageTargetFallback>
-    <RuntimeFrameworkVersion Condition=" '$(TargetFramework)' == 'netcoreapp1.0' ">1.0.4</RuntimeFrameworkVersion>
     <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
   </PropertyGroup>
 
diff --git a/src/csharp/Grpc.IntegrationTesting.QpsWorker/Grpc.IntegrationTesting.QpsWorker.csproj b/src/csharp/Grpc.IntegrationTesting.QpsWorker/Grpc.IntegrationTesting.QpsWorker.csproj
index e452257b1b..3ecefe3bc4 100755
--- a/src/csharp/Grpc.IntegrationTesting.QpsWorker/Grpc.IntegrationTesting.QpsWorker.csproj
+++ b/src/csharp/Grpc.IntegrationTesting.QpsWorker/Grpc.IntegrationTesting.QpsWorker.csproj
@@ -9,8 +9,6 @@
     <OutputType>Exe</OutputType>
     <PackageId>Grpc.IntegrationTesting.QpsWorker</PackageId>
     <ServerGarbageCollection>true</ServerGarbageCollection>
-    <PackageTargetFallback Condition=" '$(TargetFramework)' == 'netcoreapp1.0' ">$(PackageTargetFallback);portable-net45</PackageTargetFallback>
-    <RuntimeFrameworkVersion Condition=" '$(TargetFramework)' == 'netcoreapp1.0' ">1.0.4</RuntimeFrameworkVersion>
     <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
   </PropertyGroup>
 
diff --git a/src/csharp/Grpc.IntegrationTesting.Server/Grpc.IntegrationTesting.Server.csproj b/src/csharp/Grpc.IntegrationTesting.Server/Grpc.IntegrationTesting.Server.csproj
index a1fb316fdb..1092b2c21e 100755
--- a/src/csharp/Grpc.IntegrationTesting.Server/Grpc.IntegrationTesting.Server.csproj
+++ b/src/csharp/Grpc.IntegrationTesting.Server/Grpc.IntegrationTesting.Server.csproj
@@ -8,8 +8,6 @@
     <AssemblyName>Grpc.IntegrationTesting.Server</AssemblyName>
     <OutputType>Exe</OutputType>
     <PackageId>Grpc.IntegrationTesting.Server</PackageId>
-    <PackageTargetFallback Condition=" '$(TargetFramework)' == 'netcoreapp1.0' ">$(PackageTargetFallback);portable-net45</PackageTargetFallback>
-    <RuntimeFrameworkVersion Condition=" '$(TargetFramework)' == 'netcoreapp1.0' ">1.0.4</RuntimeFrameworkVersion>
     <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
   </PropertyGroup>
 
diff --git a/src/csharp/Grpc.IntegrationTesting.StressClient/Grpc.IntegrationTesting.StressClient.csproj b/src/csharp/Grpc.IntegrationTesting.StressClient/Grpc.IntegrationTesting.StressClient.csproj
index f64bea3d2b..22272547f6 100755
--- a/src/csharp/Grpc.IntegrationTesting.StressClient/Grpc.IntegrationTesting.StressClient.csproj
+++ b/src/csharp/Grpc.IntegrationTesting.StressClient/Grpc.IntegrationTesting.StressClient.csproj
@@ -8,8 +8,6 @@
     <AssemblyName>Grpc.IntegrationTesting.StressClient</AssemblyName>
     <OutputType>Exe</OutputType>
     <PackageId>Grpc.IntegrationTesting.StressClient</PackageId>
-    <PackageTargetFallback Condition=" '$(TargetFramework)' == 'netcoreapp1.0' ">$(PackageTargetFallback);portable-net45</PackageTargetFallback>
-    <RuntimeFrameworkVersion Condition=" '$(TargetFramework)' == 'netcoreapp1.0' ">1.0.4</RuntimeFrameworkVersion>
     <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
   </PropertyGroup>
 
diff --git a/src/csharp/Grpc.IntegrationTesting/Grpc.IntegrationTesting.csproj b/src/csharp/Grpc.IntegrationTesting/Grpc.IntegrationTesting.csproj
index f5077fe0f7..c02c9844e3 100755
--- a/src/csharp/Grpc.IntegrationTesting/Grpc.IntegrationTesting.csproj
+++ b/src/csharp/Grpc.IntegrationTesting/Grpc.IntegrationTesting.csproj
@@ -8,8 +8,6 @@
     <AssemblyName>Grpc.IntegrationTesting</AssemblyName>
     <OutputType>Exe</OutputType>
     <PackageId>Grpc.IntegrationTesting</PackageId>
-    <PackageTargetFallback Condition=" '$(TargetFramework)' == 'netcoreapp1.0' ">$(PackageTargetFallback);portable-net45</PackageTargetFallback>
-    <RuntimeFrameworkVersion Condition=" '$(TargetFramework)' == 'netcoreapp1.0' ">1.0.4</RuntimeFrameworkVersion>
     <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
   </PropertyGroup>
 
@@ -31,10 +29,6 @@
     <Reference Include="Microsoft.CSharp" />
   </ItemGroup>
 
-  <ItemGroup Condition=" '$(TargetFramework)' == 'netcoreapp1.0' ">
-    <PackageReference Include="System.Linq.Expressions" Version="4.1.1" />
-  </ItemGroup>
-
   <ItemGroup>
     <Compile Include="..\Grpc.Core\Version.cs" />
   </ItemGroup>
diff --git a/src/csharp/Grpc.Microbenchmarks/Grpc.Microbenchmarks.csproj b/src/csharp/Grpc.Microbenchmarks/Grpc.Microbenchmarks.csproj
index 17797e1e1e..108357e4eb 100644
--- a/src/csharp/Grpc.Microbenchmarks/Grpc.Microbenchmarks.csproj
+++ b/src/csharp/Grpc.Microbenchmarks/Grpc.Microbenchmarks.csproj
@@ -8,8 +8,6 @@
     <AssemblyName>Grpc.Microbenchmarks</AssemblyName>
     <OutputType>Exe</OutputType>
     <PackageId>Grpc.Microbenchmarks</PackageId>
-    <PackageTargetFallback Condition=" '$(TargetFramework)' == 'netcoreapp1.0' ">$(PackageTargetFallback);portable-net45</PackageTargetFallback>
-    <RuntimeFrameworkVersion Condition=" '$(TargetFramework)' == 'netcoreapp1.0' ">1.0.4</RuntimeFrameworkVersion>
     <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
   </PropertyGroup>
 
diff --git a/src/csharp/Grpc.Reflection.Tests/Grpc.Reflection.Tests.csproj b/src/csharp/Grpc.Reflection.Tests/Grpc.Reflection.Tests.csproj
index cf756c68ad..d368697124 100755
--- a/src/csharp/Grpc.Reflection.Tests/Grpc.Reflection.Tests.csproj
+++ b/src/csharp/Grpc.Reflection.Tests/Grpc.Reflection.Tests.csproj
@@ -8,8 +8,6 @@
     <AssemblyName>Grpc.Reflection.Tests</AssemblyName>
     <OutputType>Exe</OutputType>
     <PackageId>Grpc.Reflection.Tests</PackageId>
-    <PackageTargetFallback Condition=" '$(TargetFramework)' == 'netcoreapp1.0' ">$(PackageTargetFallback);portable-net45</PackageTargetFallback>
-    <RuntimeFrameworkVersion Condition=" '$(TargetFramework)' == 'netcoreapp1.0' ">1.0.4</RuntimeFrameworkVersion>
     <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
   </PropertyGroup>
 
diff --git a/src/csharp/Grpc.Reflection/Grpc.Reflection.csproj b/src/csharp/Grpc.Reflection/Grpc.Reflection.csproj
index b77fd69aee..704eea5c17 100755
--- a/src/csharp/Grpc.Reflection/Grpc.Reflection.csproj
+++ b/src/csharp/Grpc.Reflection/Grpc.Reflection.csproj
@@ -14,7 +14,6 @@
     <PackageTags>gRPC reflection</PackageTags>
     <PackageProjectUrl>https://github.com/grpc/grpc</PackageProjectUrl>
     <PackageLicenseUrl>https://github.com/grpc/grpc/blob/master/LICENSE</PackageLicenseUrl>
-    <NetStandardImplicitPackageVersion Condition=" '$(TargetFramework)' == 'netstandard1.5' ">1.6.0</NetStandardImplicitPackageVersion>
     <IncludeSymbols>true</IncludeSymbols>
     <IncludeSource>true</IncludeSource>
     <GenerateDocumentationFile>true</GenerateDocumentationFile>
diff --git a/src/csharp/doc/.gitignore b/src/csharp/doc/.gitignore
new file mode 100644
index 0000000000..09ee235efc
--- /dev/null
+++ b/src/csharp/doc/.gitignore
@@ -0,0 +1,2 @@
+html
+obj
diff --git a/src/csharp/doc/README.md b/src/csharp/doc/README.md
index 585500b5ca..46cce013a1 100644
--- a/src/csharp/doc/README.md
+++ b/src/csharp/doc/README.md
@@ -1,2 +1,9 @@
+DocFX-generated C# API Reference
+--------------------------------
 
-SandCastle project files to generate HTML reference documentation.
\ No newline at end of file
+Install docfx based on instructions here: https://github.com/dotnet/docfx
+
+```
+# generate docfx documentation into ./html directory
+$ docfx
+```
diff --git a/src/csharp/doc/docfx.json b/src/csharp/doc/docfx.json
new file mode 100644
index 0000000000..7219d0e7a6
--- /dev/null
+++ b/src/csharp/doc/docfx.json
@@ -0,0 +1,37 @@
+{
+  "metadata": [
+    {
+      "src": [
+        {
+          "files": ["Grpc.Core/Grpc.Core.csproj",
+                    "Grpc.Auth/Grpc.Auth.csproj",
+                    "Grpc.Core.Testing/Grpc.Core.Testing.csproj",
+                    "Grpc.HealthCheck/Grpc.HealthCheck.csproj",
+                    "Grpc.Reflection/Grpc.HealthCheck.csproj"],
+          "exclude": [ "**/bin/**", "**/obj/**" ],
+          "cwd": ".."
+        }
+      ],
+      "properties": { "TargetFramework": "net45" },
+      "dest": "obj/api"
+    }
+  ],
+  "build": {
+    "content": [
+      {
+        "files": [ "**/*.yml" ],
+        "cwd": "obj/api",
+        "dest": "api"
+      },
+      {
+        "files": [ "toc.yml"],
+      }
+    ],
+    "globalMetadata": {
+      "_appTitle": "gRPC C#",
+      "_enableSearch": true,
+      "_disableContribution": true
+    },
+    "dest": "html"
+  }
+}
diff --git a/src/csharp/doc/grpc_csharp_public.shfbproj b/src/csharp/doc/grpc_csharp_public.shfbproj
deleted file mode 100644
index fab953da35..0000000000
--- a/src/csharp/doc/grpc_csharp_public.shfbproj
+++ /dev/null
@@ -1,83 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<Project ToolsVersion="4.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
-  <PropertyGroup>
-    <!-- The configuration and platform will be used to determine which assemblies to include from solution and
-				 project documentation sources -->
-    <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
-    <Platform Condition=" '$(Platform)' == '' ">AnyCPU</Platform>
-    <SchemaVersion>2.0</SchemaVersion>
-    <ProjectGuid>{77e3da09-fc92-486f-a90a-99ca788e8b59}</ProjectGuid>
-    <SHFBSchemaVersion>2015.6.5.0</SHFBSchemaVersion>
-    <!-- AssemblyName, Name, and RootNamespace are not used by SHFB but Visual Studio adds them anyway -->
-    <AssemblyName>Documentation</AssemblyName>
-    <RootNamespace>Documentation</RootNamespace>
-    <Name>Documentation</Name>
-    <!-- SHFB properties -->
-    <FrameworkVersion>.NET Framework 4.5</FrameworkVersion>
-    <OutputPath>..\..\..\doc\ref\csharp\html</OutputPath>
-    <Language>en-US</Language>
-    <DocumentationSources>
-      <DocumentationSource sourceFile="..\Grpc.Auth\Grpc.Auth.csproj" />
-<DocumentationSource sourceFile="..\Grpc.Core\Grpc.Core.csproj" />
-<DocumentationSource sourceFile="..\Grpc.HealthCheck\Grpc.HealthCheck.csproj" />
-<DocumentationSource sourceFile="..\Grpc.Reflection\Grpc.Reflection.csproj" />
-<DocumentationSource sourceFile="..\Grpc.Core.Testing\Grpc.Core.Testing.csproj" /></DocumentationSources>
-    <BuildAssemblerVerbosity>OnlyWarningsAndErrors</BuildAssemblerVerbosity>
-    <HelpFileFormat>Website</HelpFileFormat>
-    <IndentHtml>False</IndentHtml>
-    <KeepLogFile>True</KeepLogFile>
-    <DisableCodeBlockComponent>False</DisableCodeBlockComponent>
-    <CleanIntermediates>True</CleanIntermediates>
-    <HelpFileVersion>1.0.0.0</HelpFileVersion>
-    <MaximumGroupParts>2</MaximumGroupParts>
-    <NamespaceGrouping>False</NamespaceGrouping>
-    <SyntaxFilters>Standard</SyntaxFilters>
-    <SdkLinkTarget>Blank</SdkLinkTarget>
-    <RootNamespaceContainer>True</RootNamespaceContainer>
-    <PresentationStyle>VS2013</PresentationStyle>
-    <Preliminary>False</Preliminary>
-    <NamingMethod>MemberName</NamingMethod>
-    <HelpTitle>gRPC C#</HelpTitle>
-    <ContentPlacement>AboveNamespaces</ContentPlacement>
-    <HtmlHelpName>Documentation</HtmlHelpName>
-    <NamespaceSummaries>
-      <NamespaceSummaryItem name="Grpc.Auth" isDocumented="True">Provides OAuth2 based authentication for gRPC. &lt;c&gt;Grpc.Auth&lt;/c&gt; currently consists of a set of very lightweight wrappers and uses C# &lt;a href="https://www.nuget.org/packages/Google.Apis.Auth/"&gt;Google.Apis.Auth&lt;/a&gt; library.</NamespaceSummaryItem>
-      <NamespaceSummaryItem name="Grpc.Core" isDocumented="True">Main namespace for gRPC C# functionality. Contains concepts representing both client side and server side gRPC logic.
-
-&lt;seealso cref="Grpc.Core.Channel"/&gt; 
-&lt;seealso cref="Grpc.Core.Server"/&gt;</NamespaceSummaryItem>
-      <NamespaceSummaryItem name="Grpc.Core.Logging" isDocumented="True">Provides functionality to redirect gRPC logs to application-specified destination.</NamespaceSummaryItem>
-      <NamespaceSummaryItem name="Grpc.Core.Utils" isDocumented="True">Various utilities for gRPC C#.</NamespaceSummaryItem>
-    </NamespaceSummaries>
-    <MissingTags>Summary, Parameter, AutoDocumentCtors, Namespace, TypeParameter, AutoDocumentDispose</MissingTags>
-  </PropertyGroup>
-  <!-- There are no properties for these groups.  AnyCPU needs to appear in order for Visual Studio to perform
-			 the build.  The others are optional common platform types that may appear. -->
-  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
-  </PropertyGroup>
-  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
-  </PropertyGroup>
-  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|x86' ">
-  </PropertyGroup>
-  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|x86' ">
-  </PropertyGroup>
-  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|x64' ">
-  </PropertyGroup>
-  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|x64' ">
-  </PropertyGroup>
-  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|Win32' ">
-  </PropertyGroup>
-  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|Win32' ">
-  </PropertyGroup>
-  <!-- Import the SHFB build targets -->
-  <Import Project="$(SHFBROOT)\SandcastleHelpFileBuilder.targets" />
-  <!-- The pre-build and post-build event properties must appear *after* the targets file import in order to be
-			 evaluated correctly. -->
-  <PropertyGroup>
-    <PreBuildEvent>
-    </PreBuildEvent>
-    <PostBuildEvent>
-    </PostBuildEvent>
-    <RunPostBuildEvent>OnBuildSuccess</RunPostBuildEvent>
-  </PropertyGroup>
-</Project>
\ No newline at end of file
diff --git a/src/csharp/doc/toc.yml b/src/csharp/doc/toc.yml
new file mode 100644
index 0000000000..c3a1e415ab
--- /dev/null
+++ b/src/csharp/doc/toc.yml
@@ -0,0 +1,3 @@
+- name: API Documentation
+  href: obj/api/
+  homepage: obj/api/Grpc.Core.yml
diff --git a/src/python/grpcio/grpc/_cython/_cygrpc/completion_queue.pyx.pxi b/src/python/grpcio/grpc/_cython/_cygrpc/completion_queue.pyx.pxi
index 28c30e5d35..237f430799 100644
--- a/src/python/grpcio/grpc/_cython/_cygrpc/completion_queue.pyx.pxi
+++ b/src/python/grpcio/grpc/_cython/_cygrpc/completion_queue.pyx.pxi
@@ -41,9 +41,8 @@ cdef class CompletionQueue:
     cdef object user_tag = None
     cdef Call operation_call = None
     cdef CallDetails request_call_details = None
-    cdef Metadata request_metadata = None
+    cdef object request_metadata = None
     cdef Operations batch_operations = None
-    cdef Operation batch_operation = None
     if event.type == GRPC_QUEUE_TIMEOUT:
       return Event(
           event.type, False, None, None, None, None, False, None)
@@ -63,14 +62,8 @@ cdef class CompletionQueue:
         operation_call = tag.operation_call
         request_call_details = tag.request_call_details
         if tag.request_metadata is not None:
-          request_metadata = tag.request_metadata
-          request_metadata._claim_slice_ownership()
+          request_metadata = tuple(tag.request_metadata)
         batch_operations = tag.batch_operations
-        if tag.batch_operations is not None:
-          for op in batch_operations.operations:
-            batch_operation = <Operation>op
-            if batch_operation._received_metadata is not None:
-              batch_operation._received_metadata._claim_slice_ownership()
         if tag.is_new_request:
           # Stuff in the tag not explicitly handled by us needs to live through
           # the life of the call
diff --git a/src/python/grpcio/grpc/_cython/_cygrpc/credentials.pyx.pxi b/src/python/grpcio/grpc/_cython/_cygrpc/credentials.pyx.pxi
index 98d7a9820d..57816f1cab 100644
--- a/src/python/grpcio/grpc/_cython/_cygrpc/credentials.pyx.pxi
+++ b/src/python/grpcio/grpc/_cython/_cygrpc/credentials.pyx.pxi
@@ -76,7 +76,7 @@ cdef class CredentialsMetadataPlugin:
     """
     Args:
       plugin_callback (callable): Callback accepting a service URL (str/bytes)
-        and callback object (accepting a Metadata,
+        and callback object (accepting a MetadataArray,
         grpc_status_code, and a str/bytes error message). This argument
         when called should be non-blocking and eventually call the callback
         object with the appropriate status code/details and metadata (if
@@ -129,8 +129,7 @@ cdef void plugin_get_metadata(
   def python_callback(
       Metadata metadata, grpc_status_code status,
       bytes error_details):
-    cb(user_data, metadata.c_metadata_array.metadata,
-       metadata.c_metadata_array.count, status, error_details)
+    cb(user_data, metadata.c_metadata, metadata.c_count, status, error_details)
     called_flag[0] = True
   cdef CredentialsMetadataPlugin self = <CredentialsMetadataPlugin>state
   cdef AuthMetadataContext cy_context = AuthMetadataContext()
@@ -139,8 +138,8 @@ cdef void plugin_get_metadata(
     self.plugin_callback(cy_context, python_callback)
   except Exception as error:
     if not called_flag[0]:
-      cb(user_data, Metadata([]).c_metadata_array.metadata,
-         0, StatusCode.unknown, traceback.format_exc().encode())
+      cb(user_data, NULL, 0, StatusCode.unknown,
+         traceback.format_exc().encode())
 
 cdef void plugin_destroy_c_plugin_state(void *state) with gil:
   cpython.Py_DECREF(<CredentialsMetadataPlugin>state)
diff --git a/src/python/grpcio/grpc/_cython/_cygrpc/grpc.pxi b/src/python/grpcio/grpc/_cython/_cygrpc/grpc.pxi
index 5950bfa0e6..28cf114451 100644
--- a/src/python/grpcio/grpc/_cython/_cygrpc/grpc.pxi
+++ b/src/python/grpcio/grpc/_cython/_cygrpc/grpc.pxi
@@ -59,6 +59,7 @@ cdef extern from "grpc/grpc.h":
   grpc_slice grpc_slice_malloc(size_t length) nogil
   grpc_slice grpc_slice_from_copied_string(const char *source) nogil
   grpc_slice grpc_slice_from_copied_buffer(const char *source, size_t len) nogil
+  grpc_slice grpc_slice_copy(grpc_slice s) nogil
 
   # Declare functions for function-like macros (because Cython)...
   void *grpc_slice_start_ptr "GRPC_SLICE_START_PTR" (grpc_slice s) nogil
diff --git a/src/python/grpcio/grpc/_cython/_cygrpc/records.pxd.pxi b/src/python/grpcio/grpc/_cython/_cygrpc/records.pxd.pxi
index 8ace6aeb52..9c40ebf0c2 100644
--- a/src/python/grpcio/grpc/_cython/_cygrpc/records.pxd.pxi
+++ b/src/python/grpcio/grpc/_cython/_cygrpc/records.pxd.pxi
@@ -37,7 +37,7 @@ cdef class OperationTag:
   cdef Server shutting_down_server
   cdef Call operation_call
   cdef CallDetails request_call_details
-  cdef Metadata request_metadata
+  cdef MetadataArray request_metadata
   cdef Operations batch_operations
   cdef bint is_new_request
 
@@ -51,7 +51,7 @@ cdef class Event:
   # For Server.request_call
   cdef readonly bint is_new_request
   cdef readonly CallDetails request_call_details
-  cdef readonly Metadata request_metadata
+  cdef readonly object request_metadata
 
   # For server calls
   cdef readonly Call operation_call
@@ -92,15 +92,20 @@ cdef class Metadatum:
 
 cdef class Metadata:
 
+  cdef grpc_metadata *c_metadata
+  cdef readonly size_t c_count
+
+
+cdef class MetadataArray:
+
   cdef grpc_metadata_array c_metadata_array
-  cdef void _claim_slice_ownership(self)
 
 
 cdef class Operation:
 
   cdef grpc_op c_op
   cdef ByteBuffer _received_message
-  cdef Metadata _received_metadata
+  cdef MetadataArray _received_metadata
   cdef grpc_status_code _received_status_code
   cdef grpc_slice _status_details
   cdef int _received_cancelled
diff --git a/src/python/grpcio/grpc/_cython/_cygrpc/records.pyx.pxi b/src/python/grpcio/grpc/_cython/_cygrpc/records.pyx.pxi
index 1b2ddd2469..0a2a6eee05 100644
--- a/src/python/grpcio/grpc/_cython/_cygrpc/records.pyx.pxi
+++ b/src/python/grpcio/grpc/_cython/_cygrpc/records.pyx.pxi
@@ -238,7 +238,7 @@ cdef class Event:
   def __cinit__(self, grpc_completion_type type, bint success,
                 object tag, Call operation_call,
                 CallDetails request_call_details,
-                Metadata request_metadata,
+                object request_metadata,
                 bint is_new_request,
                 Operations batch_operations):
     self.type = type
@@ -437,48 +437,79 @@ cdef class Metadatum:
 cdef class _MetadataIterator:
 
   cdef size_t i
-  cdef Metadata metadata
+  cdef size_t _length
+  cdef object _metadatum_indexable
 
-  def __cinit__(self, Metadata metadata not None):
+  def __cinit__(self, length, metadatum_indexable):
+    self._length = length
+    self._metadatum_indexable = metadatum_indexable
     self.i = 0
-    self.metadata = metadata
 
   def __iter__(self):
     return self
 
   def __next__(self):
-    if self.i < len(self.metadata):
-      result = self.metadata[self.i]
+    if self.i < self._length:
+      result = self._metadatum_indexable[self.i]
       self.i = self.i + 1
       return result
     else:
       raise StopIteration
 
 
+# TODO(https://github.com/grpc/grpc/issues/7950): Eliminate this; just use an
+# ordinary sequence of pairs of bytestrings all the way down to the
+# grpc_call_start_batch call.
 cdef class Metadata:
+  """Metadata being passed from application to core."""
 
   def __cinit__(self, metadata_iterable):
+    metadata_sequence = tuple(metadata_iterable)
+    cdef size_t count = len(metadata_sequence)
     with nogil:
       grpc_init()
-      grpc_metadata_array_init(&self.c_metadata_array)
-    metadata = list(metadata_iterable)
-    for metadatum in metadata:
-      if not isinstance(metadatum, Metadatum):
-        raise TypeError("expected list of Metadatum")
-    self.c_metadata_array.count = len(metadata)
-    self.c_metadata_array.capacity = len(metadata)
+      self.c_metadata = <grpc_metadata *>gpr_malloc(
+          count * sizeof(grpc_metadata))
+      self.c_count = count
+    for index, metadatum in enumerate(metadata_sequence):
+      self.c_metadata[index].key = grpc_slice_copy(
+          (<Metadatum>metadatum).c_metadata.key)
+      self.c_metadata[index].value = grpc_slice_copy(
+          (<Metadatum>metadatum).c_metadata.value)
+
+  def __dealloc__(self):
+    with nogil:
+      for index in range(self.c_count):
+        grpc_slice_unref(self.c_metadata[index].key)
+        grpc_slice_unref(self.c_metadata[index].value)
+      gpr_free(self.c_metadata)
+      grpc_shutdown()
+
+  def __len__(self):
+    return self.c_count
+
+  def __getitem__(self, size_t index):
+    if index < self.c_count:
+      key = _slice_bytes(self.c_metadata[index].key)
+      value = _slice_bytes(self.c_metadata[index].value)
+      return Metadatum(key, value)
+    else:
+      raise IndexError()
+
+  def __iter__(self):
+    return _MetadataIterator(self.c_count, self)
+
+
+cdef class MetadataArray:
+  """Metadata being passed from core to application."""
+
+  def __cinit__(self):
     with nogil:
-      self.c_metadata_array.metadata = <grpc_metadata *>gpr_malloc(
-          self.c_metadata_array.count*sizeof(grpc_metadata)
-      )
-    for i in range(self.c_metadata_array.count):
-      (<Metadatum>metadata[i])._copy_metadatum(&self.c_metadata_array.metadata[i])
+      grpc_init()
+      grpc_metadata_array_init(&self.c_metadata_array)
 
   def __dealloc__(self):
     with nogil:
-      # this frees the allocated memory for the grpc_metadata_array (although
-      # it'd be nice if that were documented somewhere...)
-      # TODO(atash): document this in the C core
       grpc_metadata_array_destroy(&self.c_metadata_array)
       grpc_shutdown()
 
@@ -493,21 +524,7 @@ cdef class Metadata:
     return Metadatum(key=key, value=value)
 
   def __iter__(self):
-    return _MetadataIterator(self)
-
-  cdef void _claim_slice_ownership(self):
-    cdef grpc_metadata_array new_c_metadata_array
-    grpc_metadata_array_init(&new_c_metadata_array)
-    new_c_metadata_array.metadata = <grpc_metadata *>gpr_malloc(
-        self.c_metadata_array.count*sizeof(grpc_metadata))
-    new_c_metadata_array.count = self.c_metadata_array.count
-    for i in range(self.c_metadata_array.count):
-      new_c_metadata_array.metadata[i].key = _copy_slice(
-          self.c_metadata_array.metadata[i].key)
-      new_c_metadata_array.metadata[i].value = _copy_slice(
-          self.c_metadata_array.metadata[i].value)
-    grpc_metadata_array_destroy(&self.c_metadata_array)
-    self.c_metadata_array = new_c_metadata_array
+    return _MetadataIterator(self.c_metadata_array.count, self)
 
 
 cdef class Operation:
@@ -547,14 +564,13 @@ cdef class Operation:
     if (self.c_op.type != GRPC_OP_RECV_INITIAL_METADATA and
         self.c_op.type != GRPC_OP_RECV_STATUS_ON_CLIENT):
       raise TypeError("self must be an operation receiving metadata")
-    return self._received_metadata
-
-  @property
-  def received_metadata_or_none(self):
-    if (self.c_op.type != GRPC_OP_RECV_INITIAL_METADATA and
-        self.c_op.type != GRPC_OP_RECV_STATUS_ON_CLIENT):
-      return None
-    return self._received_metadata
+    # TODO(https://github.com/grpc/grpc/issues/7950): Drop the "all Cython
+    # objects must be legitimate for use from Python at any time" policy in
+    # place today, shift the policy toward "Operation objects are only usable
+    # while their calls are active", and move this making-a-copy-because-this-
+    # data-needs-to-live-much-longer-than-the-call-from-which-it-arose to the
+    # lowest Python layer.
+    return tuple(self._received_metadata)
 
   @property
   def received_status_code(self):
@@ -601,9 +617,8 @@ def operation_send_initial_metadata(Metadata metadata, int flags):
   cdef Operation op = Operation()
   op.c_op.type = GRPC_OP_SEND_INITIAL_METADATA
   op.c_op.flags = flags
-  op.c_op.data.send_initial_metadata.count = metadata.c_metadata_array.count
-  op.c_op.data.send_initial_metadata.metadata = (
-      metadata.c_metadata_array.metadata)
+  op.c_op.data.send_initial_metadata.count = metadata.c_count
+  op.c_op.data.send_initial_metadata.metadata = metadata.c_metadata
   op.references.append(metadata)
   op.is_valid = True
   return op
@@ -631,9 +646,8 @@ def operation_send_status_from_server(
   op.c_op.type = GRPC_OP_SEND_STATUS_FROM_SERVER
   op.c_op.flags = flags
   op.c_op.data.send_status_from_server.trailing_metadata_count = (
-      metadata.c_metadata_array.count)
-  op.c_op.data.send_status_from_server.trailing_metadata = (
-      metadata.c_metadata_array.metadata)
+      metadata.c_count)
+  op.c_op.data.send_status_from_server.trailing_metadata = metadata.c_metadata
   op.c_op.data.send_status_from_server.status = code
   grpc_slice_unref(op._status_details)
   op._status_details = _slice_from_bytes(details)
@@ -646,7 +660,7 @@ def operation_receive_initial_metadata(int flags):
   cdef Operation op = Operation()
   op.c_op.type = GRPC_OP_RECV_INITIAL_METADATA
   op.c_op.flags = flags
-  op._received_metadata = Metadata([])
+  op._received_metadata = MetadataArray()
   op.c_op.data.receive_initial_metadata.receive_initial_metadata = (
       &op._received_metadata.c_metadata_array)
   op.is_valid = True
@@ -669,7 +683,7 @@ def operation_receive_status_on_client(int flags):
   cdef Operation op = Operation()
   op.c_op.type = GRPC_OP_RECV_STATUS_ON_CLIENT
   op.c_op.flags = flags
-  op._received_metadata = Metadata([])
+  op._received_metadata = MetadataArray()
   op.c_op.data.receive_status_on_client.trailing_metadata = (
       &op._received_metadata.c_metadata_array)
   op.c_op.data.receive_status_on_client.status = (
diff --git a/src/python/grpcio/grpc/_cython/_cygrpc/server.pyx.pxi b/src/python/grpcio/grpc/_cython/_cygrpc/server.pyx.pxi
index dd276fd57b..b8db27469f 100644
--- a/src/python/grpcio/grpc/_cython/_cygrpc/server.pyx.pxi
+++ b/src/python/grpcio/grpc/_cython/_cygrpc/server.pyx.pxi
@@ -44,7 +44,7 @@ cdef class Server:
     cdef OperationTag operation_tag = OperationTag(tag)
     operation_tag.operation_call = Call()
     operation_tag.request_call_details = CallDetails()
-    operation_tag.request_metadata = Metadata([])
+    operation_tag.request_metadata = MetadataArray()
     operation_tag.references.extend([self, call_queue, server_queue])
     operation_tag.is_new_request = True
     operation_tag.batch_operations = Operations([])
diff --git a/src/python/grpcio_health_checking/setup.py b/src/python/grpcio_health_checking/setup.py
index 0299b4cca9..1f5e9c5130 100644
--- a/src/python/grpcio_health_checking/setup.py
+++ b/src/python/grpcio_health_checking/setup.py
@@ -34,7 +34,7 @@ CLASSIFIERS = [
     'Programming Language :: Python :: 3.5',
     'Programming Language :: Python :: 3.6',
     'License :: OSI Approved :: Apache Software License',
-],
+]
 
 PACKAGE_DIRECTORIES = {
     '': '.',
diff --git a/src/python/grpcio_reflection/setup.py b/src/python/grpcio_reflection/setup.py
index bed2311b59..9360550afb 100644
--- a/src/python/grpcio_reflection/setup.py
+++ b/src/python/grpcio_reflection/setup.py
@@ -35,7 +35,7 @@ CLASSIFIERS = [
     'Programming Language :: Python :: 3.5',
     'Programming Language :: Python :: 3.6',
     'License :: OSI Approved :: Apache Software License',
-],
+]
 
 PACKAGE_DIRECTORIES = {
     '': '.',
diff --git a/src/python/grpcio_testing/grpc_version.py b/src/python/grpcio_testing/grpc_version.py
index 41a75d46f6..592d08efc3 100644
--- a/src/python/grpcio_testing/grpc_version.py
+++ b/src/python/grpcio_testing/grpc_version.py
@@ -12,6 +12,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-# AUTO-GENERATED FROM `$REPO_ROOT/templates/src/python/grpcio_reflection/grpc_version.py.template`!!!
+# AUTO-GENERATED FROM `$REPO_ROOT/templates/src/python/grpcio_testing/grpc_version.py.template`!!!
 
-VERSION = '1.5.0.dev0'
+VERSION='1.7.0.dev0'
diff --git a/src/python/grpcio_tests/tests/protoc_plugin/beta_python_plugin_test.py b/src/python/grpcio_tests/tests/protoc_plugin/beta_python_plugin_test.py
index 83f21ecbbb..424b153ff8 100644
--- a/src/python/grpcio_tests/tests/protoc_plugin/beta_python_plugin_test.py
+++ b/src/python/grpcio_tests/tests/protoc_plugin/beta_python_plugin_test.py
@@ -12,19 +12,15 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import argparse
 import contextlib
-import distutils.spawn
-import errno
-import itertools
+import importlib
 import os
-import pkg_resources
+from os import path
+import pkgutil
 import shutil
-import subprocess
 import sys
 import tempfile
 import threading
-import time
 import unittest
 
 from six import moves
@@ -33,12 +29,22 @@ from grpc.beta import implementations
 from grpc.beta import interfaces
 from grpc.framework.foundation import future
 from grpc.framework.interfaces.face import face
+from grpc_tools import protoc
 from tests.unit.framework.common import test_constants
 
-import tests.protoc_plugin.protos.payload.test_payload_pb2 as payload_pb2
-import tests.protoc_plugin.protos.requests.r.test_requests_pb2 as request_pb2
-import tests.protoc_plugin.protos.responses.test_responses_pb2 as response_pb2
-import tests.protoc_plugin.protos.service.test_service_pb2 as service_pb2
+_RELATIVE_PROTO_PATH = 'relative_proto_path'
+_RELATIVE_PYTHON_OUT = 'relative_python_out'
+
+_PROTO_FILES_PATH_COMPONENTS = (
+    ('beta_grpc_plugin_test', 'payload', 'test_payload.proto',),
+    ('beta_grpc_plugin_test', 'requests', 'r', 'test_requests.proto',),
+    ('beta_grpc_plugin_test', 'responses', 'test_responses.proto',),
+    ('beta_grpc_plugin_test', 'service', 'test_service.proto',),)
+
+_PAYLOAD_PB2 = 'beta_grpc_plugin_test.payload.test_payload_pb2'
+_REQUESTS_PB2 = 'beta_grpc_plugin_test.requests.r.test_requests_pb2'
+_RESPONSES_PB2 = 'beta_grpc_plugin_test.responses.test_responses_pb2'
+_SERVICE_PB2 = 'beta_grpc_plugin_test.service.test_service_pb2'
 
 # Identifiers of entities we expect to find in the generated module.
 SERVICER_IDENTIFIER = 'BetaTestServiceServicer'
@@ -47,12 +53,50 @@ SERVER_FACTORY_IDENTIFIER = 'beta_create_TestService_server'
 STUB_FACTORY_IDENTIFIER = 'beta_create_TestService_stub'
 
 
+@contextlib.contextmanager
+def _system_path(path_insertion):
+    old_system_path = sys.path[:]
+    sys.path = sys.path[0:1] + path_insertion + sys.path[1:]
+    yield
+    sys.path = old_system_path
+
+
+def _create_directory_tree(root, path_components_sequence):
+    created = set()
+    for path_components in path_components_sequence:
+        thus_far = ''
+        for path_component in path_components:
+            relative_path = path.join(thus_far, path_component)
+            if relative_path not in created:
+                os.makedirs(path.join(root, relative_path))
+                created.add(relative_path)
+            thus_far = path.join(thus_far, path_component)
+
+
+def _massage_proto_content(raw_proto_content):
+    imports_substituted = raw_proto_content.replace(
+        b'import "tests/protoc_plugin/protos/',
+        b'import "beta_grpc_plugin_test/')
+    package_statement_substituted = imports_substituted.replace(
+        b'package grpc_protoc_plugin;', b'package beta_grpc_protoc_plugin;')
+    return package_statement_substituted
+
+
+def _packagify(directory):
+    for subdirectory, _, _ in os.walk(directory):
+        init_file_name = path.join(subdirectory, '__init__.py')
+        with open(init_file_name, 'wb') as init_file:
+            init_file.write(b'')
+
+
 class _ServicerMethods(object):
 
-    def __init__(self):
+    def __init__(self, payload_pb2, responses_pb2):
         self._condition = threading.Condition()
         self._paused = False
         self._fail = False
+        self._payload_pb2 = payload_pb2
+        self._responses_pb2 = responses_pb2
 
     @contextlib.contextmanager
     def pause(self):  # pylint: disable=invalid-name
@@ -79,22 +123,22 @@ class _ServicerMethods(object):
                 self._condition.wait()
 
     def UnaryCall(self, request, unused_rpc_context):
-        response = response_pb2.SimpleResponse()
-        response.payload.payload_type = payload_pb2.COMPRESSABLE
+        response = self._responses_pb2.SimpleResponse()
+        response.payload.payload_type = self._payload_pb2.COMPRESSABLE
         response.payload.payload_compressable = 'a' * request.response_size
         self._control()
         return response
 
     def StreamingOutputCall(self, request, unused_rpc_context):
         for parameter in request.response_parameters:
-            response = response_pb2.StreamingOutputCallResponse()
-            response.payload.payload_type = payload_pb2.COMPRESSABLE
+            response = self._responses_pb2.StreamingOutputCallResponse()
+            response.payload.payload_type = self._payload_pb2.COMPRESSABLE
             response.payload.payload_compressable = 'a' * parameter.size
             self._control()
             yield response
 
     def StreamingInputCall(self, request_iter, unused_rpc_context):
-        response = response_pb2.StreamingInputCallResponse()
+        response = self._responses_pb2.StreamingInputCallResponse()
         aggregated_payload_size = 0
         for request in request_iter:
             aggregated_payload_size += len(request.payload.payload_compressable)
@@ -105,8 +149,8 @@ class _ServicerMethods(object):
     def FullDuplexCall(self, request_iter, unused_rpc_context):
         for request in request_iter:
             for parameter in request.response_parameters:
-                response = response_pb2.StreamingOutputCallResponse()
-                response.payload.payload_type = payload_pb2.COMPRESSABLE
+                response = self._responses_pb2.StreamingOutputCallResponse()
+                response.payload.payload_type = self._payload_pb2.COMPRESSABLE
                 response.payload.payload_compressable = 'a' * parameter.size
                 self._control()
                 yield response
@@ -115,8 +159,8 @@ class _ServicerMethods(object):
         responses = []
         for request in request_iter:
             for parameter in request.response_parameters:
-                response = response_pb2.StreamingOutputCallResponse()
-                response.payload.payload_type = payload_pb2.COMPRESSABLE
+                response = self._responses_pb2.StreamingOutputCallResponse()
+                response.payload.payload_type = self._payload_pb2.COMPRESSABLE
                 response.payload.payload_compressable = 'a' * parameter.size
                 self._control()
                 responses.append(response)
@@ -125,7 +169,7 @@ class _ServicerMethods(object):
 
 
 @contextlib.contextmanager
-def _CreateService():
+def _CreateService(payload_pb2, responses_pb2, service_pb2):
     """Provides a servicer backend and a stub.
 
   The servicer is just the implementation of the actual servicer passed to the
@@ -136,7 +180,7 @@ def _CreateService():
       the service bound to the stub and and stub is the stub on which to invoke
       RPCs.
   """
-    servicer_methods = _ServicerMethods()
+    servicer_methods = _ServicerMethods(payload_pb2, responses_pb2)
 
     class Servicer(getattr(service_pb2, SERVICER_IDENTIFIER)):
 
@@ -161,12 +205,12 @@ def _CreateService():
     server.start()
     channel = implementations.insecure_channel('localhost', port)
     stub = getattr(service_pb2, STUB_FACTORY_IDENTIFIER)(channel)
-    yield (servicer_methods, stub)
+    yield servicer_methods, stub,
     server.stop(0)
 
 
 @contextlib.contextmanager
-def _CreateIncompleteService():
+def _CreateIncompleteService(service_pb2):
     """Provides a servicer backend that fails to implement methods and its stub.
 
   The servicer is just the implementation of the actual servicer passed to the
@@ -192,16 +236,16 @@ def _CreateIncompleteService():
     server.stop(0)
 
 
-def _streaming_input_request_iterator():
+def _streaming_input_request_iterator(payload_pb2, requests_pb2):
     for _ in range(3):
-        request = request_pb2.StreamingInputCallRequest()
+        request = requests_pb2.StreamingInputCallRequest()
         request.payload.payload_type = payload_pb2.COMPRESSABLE
         request.payload.payload_compressable = 'a'
         yield request
 
 
-def _streaming_output_request():
-    request = request_pb2.StreamingOutputCallRequest()
+def _streaming_output_request(requests_pb2):
+    request = requests_pb2.StreamingOutputCallRequest()
     sizes = [1, 2, 3]
     request.response_parameters.add(size=sizes[0], interval_us=0)
     request.response_parameters.add(size=sizes[1], interval_us=0)
@@ -209,11 +253,11 @@ def _streaming_output_request():
     return request
 
 
-def _full_duplex_request_iterator():
-    request = request_pb2.StreamingOutputCallRequest()
+def _full_duplex_request_iterator(requests_pb2):
+    request = requests_pb2.StreamingOutputCallRequest()
     request.response_parameters.add(size=1, interval_us=0)
     yield request
-    request = request_pb2.StreamingOutputCallRequest()
+    request = requests_pb2.StreamingOutputCallRequest()
     request.response_parameters.add(size=2, interval_us=0)
     request.response_parameters.add(size=3, interval_us=0)
     yield request
@@ -227,22 +271,78 @@ class PythonPluginTest(unittest.TestCase):
   methods and does not exist for response-streaming methods.
   """
 
+    def setUp(self):
+        self._directory = tempfile.mkdtemp(dir='.')
+        self._proto_path = path.join(self._directory, _RELATIVE_PROTO_PATH)
+        self._python_out = path.join(self._directory, _RELATIVE_PYTHON_OUT)
+
+        os.makedirs(self._proto_path)
+        os.makedirs(self._python_out)
+
+        directories_path_components = {
+            proto_file_path_components[:-1]
+            for proto_file_path_components in _PROTO_FILES_PATH_COMPONENTS
+        }
+        _create_directory_tree(self._proto_path, directories_path_components)
+        self._proto_file_names = set()
+        for proto_file_path_components in _PROTO_FILES_PATH_COMPONENTS:
+            raw_proto_content = pkgutil.get_data(
+                'tests.protoc_plugin.protos',
+                path.join(*proto_file_path_components[1:]))
+            massaged_proto_content = _massage_proto_content(raw_proto_content)
+            proto_file_name = path.join(self._proto_path,
+                                        *proto_file_path_components)
+            with open(proto_file_name, 'wb') as proto_file:
+                proto_file.write(massaged_proto_content)
+            self._proto_file_names.add(proto_file_name)
+
+    def tearDown(self):
+        shutil.rmtree(self._directory)
+
+    def _protoc(self):
+        args = [
+            '',
+            '--proto_path={}'.format(self._proto_path),
+            '--python_out={}'.format(self._python_out),
+            '--grpc_python_out=grpc_1_0:{}'.format(self._python_out),
+        ] + list(self._proto_file_names)
+        protoc_exit_code = protoc.main(args)
+        self.assertEqual(0, protoc_exit_code)
+
+        _packagify(self._python_out)
+
+        with _system_path([
+                self._python_out,
+        ]):
+            self._payload_pb2 = importlib.import_module(_PAYLOAD_PB2)
+            self._requests_pb2 = importlib.import_module(_REQUESTS_PB2)
+            self._responses_pb2 = importlib.import_module(_RESPONSES_PB2)
+            self._service_pb2 = importlib.import_module(_SERVICE_PB2)
+
     def testImportAttributes(self):
+        self._protoc()
+
         # check that we can access the generated module and its members.
-        self.assertIsNotNone(getattr(service_pb2, SERVICER_IDENTIFIER, None))
-        self.assertIsNotNone(getattr(service_pb2, STUB_IDENTIFIER, None))
         self.assertIsNotNone(
-            getattr(service_pb2, SERVER_FACTORY_IDENTIFIER, None))
+            getattr(self._service_pb2, SERVICER_IDENTIFIER, None))
+        self.assertIsNotNone(getattr(self._service_pb2, STUB_IDENTIFIER, None))
         self.assertIsNotNone(
-            getattr(service_pb2, STUB_FACTORY_IDENTIFIER, None))
+            getattr(self._service_pb2, SERVER_FACTORY_IDENTIFIER, None))
+        self.assertIsNotNone(
+            getattr(self._service_pb2, STUB_FACTORY_IDENTIFIER, None))
 
     def testUpDown(self):
-        with _CreateService():
-            request_pb2.SimpleRequest(response_size=13)
+        self._protoc()
+
+        with _CreateService(self._payload_pb2, self._responses_pb2,
+                            self._service_pb2):
+            self._requests_pb2.SimpleRequest(response_size=13)
 
     def testIncompleteServicer(self):
-        with _CreateIncompleteService() as (_, stub):
-            request = request_pb2.SimpleRequest(response_size=13)
+        self._protoc()
+
+        with _CreateIncompleteService(self._service_pb2) as (_, stub):
+            request = self._requests_pb2.SimpleRequest(response_size=13)
             try:
                 stub.UnaryCall(request, test_constants.LONG_TIMEOUT)
             except face.AbortionError as error:
@@ -250,15 +350,21 @@ class PythonPluginTest(unittest.TestCase):
                                  error.code)
 
     def testUnaryCall(self):
-        with _CreateService() as (methods, stub):
-            request = request_pb2.SimpleRequest(response_size=13)
+        self._protoc()
+
+        with _CreateService(self._payload_pb2, self._responses_pb2,
+                            self._service_pb2) as (methods, stub):
+            request = self._requests_pb2.SimpleRequest(response_size=13)
             response = stub.UnaryCall(request, test_constants.LONG_TIMEOUT)
         expected_response = methods.UnaryCall(request, 'not a real context!')
         self.assertEqual(expected_response, response)
 
     def testUnaryCallFuture(self):
-        with _CreateService() as (methods, stub):
-            request = request_pb2.SimpleRequest(response_size=13)
+        self._protoc()
+
+        with _CreateService(self._payload_pb2, self._responses_pb2,
+                            self._service_pb2) as (methods, stub):
+            request = self._requests_pb2.SimpleRequest(response_size=13)
             # Check that the call does not block waiting for the server to respond.
             with methods.pause():
                 response_future = stub.UnaryCall.future(
@@ -268,8 +374,11 @@ class PythonPluginTest(unittest.TestCase):
         self.assertEqual(expected_response, response)
 
     def testUnaryCallFutureExpired(self):
-        with _CreateService() as (methods, stub):
-            request = request_pb2.SimpleRequest(response_size=13)
+        self._protoc()
+
+        with _CreateService(self._payload_pb2, self._responses_pb2,
+                            self._service_pb2) as (methods, stub):
+            request = self._requests_pb2.SimpleRequest(response_size=13)
             with methods.pause():
                 response_future = stub.UnaryCall.future(
                     request, test_constants.SHORT_TIMEOUT)
@@ -277,24 +386,33 @@ class PythonPluginTest(unittest.TestCase):
                     response_future.result()
 
     def testUnaryCallFutureCancelled(self):
-        with _CreateService() as (methods, stub):
-            request = request_pb2.SimpleRequest(response_size=13)
+        self._protoc()
+
+        with _CreateService(self._payload_pb2, self._responses_pb2,
+                            self._service_pb2) as (methods, stub):
+            request = self._requests_pb2.SimpleRequest(response_size=13)
             with methods.pause():
                 response_future = stub.UnaryCall.future(request, 1)
                 response_future.cancel()
                 self.assertTrue(response_future.cancelled())
 
     def testUnaryCallFutureFailed(self):
-        with _CreateService() as (methods, stub):
-            request = request_pb2.SimpleRequest(response_size=13)
+        self._protoc()
+
+        with _CreateService(self._payload_pb2, self._responses_pb2,
+                            self._service_pb2) as (methods, stub):
+            request = self._requests_pb2.SimpleRequest(response_size=13)
             with methods.fail():
                 response_future = stub.UnaryCall.future(
                     request, test_constants.LONG_TIMEOUT)
                 self.assertIsNotNone(response_future.exception())
 
     def testStreamingOutputCall(self):
-        with _CreateService() as (methods, stub):
-            request = _streaming_output_request()
+        self._protoc()
+
+        with _CreateService(self._payload_pb2, self._responses_pb2,
+                            self._service_pb2) as (methods, stub):
+            request = _streaming_output_request(self._requests_pb2)
             responses = stub.StreamingOutputCall(request,
                                                  test_constants.LONG_TIMEOUT)
             expected_responses = methods.StreamingOutputCall(
@@ -304,8 +422,11 @@ class PythonPluginTest(unittest.TestCase):
                 self.assertEqual(expected_response, response)
 
     def testStreamingOutputCallExpired(self):
-        with _CreateService() as (methods, stub):
-            request = _streaming_output_request()
+        self._protoc()
+
+        with _CreateService(self._payload_pb2, self._responses_pb2,
+                            self._service_pb2) as (methods, stub):
+            request = _streaming_output_request(self._requests_pb2)
             with methods.pause():
                 responses = stub.StreamingOutputCall(
                     request, test_constants.SHORT_TIMEOUT)
@@ -313,8 +434,11 @@ class PythonPluginTest(unittest.TestCase):
                     list(responses)
 
     def testStreamingOutputCallCancelled(self):
-        with _CreateService() as (methods, stub):
-            request = _streaming_output_request()
+        self._protoc()
+
+        with _CreateService(self._payload_pb2, self._responses_pb2,
+                            self._service_pb2) as (methods, stub):
+            request = _streaming_output_request(self._requests_pb2)
             responses = stub.StreamingOutputCall(request,
                                                  test_constants.LONG_TIMEOUT)
             next(responses)
@@ -323,8 +447,11 @@ class PythonPluginTest(unittest.TestCase):
                 next(responses)
 
     def testStreamingOutputCallFailed(self):
-        with _CreateService() as (methods, stub):
-            request = _streaming_output_request()
+        self._protoc()
+
+        with _CreateService(self._payload_pb2, self._responses_pb2,
+                            self._service_pb2) as (methods, stub):
+            request = _streaming_output_request(self._requests_pb2)
             with methods.fail():
                 responses = stub.StreamingOutputCall(request, 1)
                 self.assertIsNotNone(responses)
@@ -332,30 +459,46 @@ class PythonPluginTest(unittest.TestCase):
                     next(responses)
 
     def testStreamingInputCall(self):
-        with _CreateService() as (methods, stub):
+        self._protoc()
+
+        with _CreateService(self._payload_pb2, self._responses_pb2,
+                            self._service_pb2) as (methods, stub):
             response = stub.StreamingInputCall(
-                _streaming_input_request_iterator(),
+                _streaming_input_request_iterator(self._payload_pb2,
+                                                  self._requests_pb2),
                 test_constants.LONG_TIMEOUT)
         expected_response = methods.StreamingInputCall(
-            _streaming_input_request_iterator(), 'not a real RpcContext!')
+            _streaming_input_request_iterator(self._payload_pb2,
+                                              self._requests_pb2),
+            'not a real RpcContext!')
         self.assertEqual(expected_response, response)
 
     def testStreamingInputCallFuture(self):
-        with _CreateService() as (methods, stub):
+        self._protoc()
+
+        with _CreateService(self._payload_pb2, self._responses_pb2,
+                            self._service_pb2) as (methods, stub):
             with methods.pause():
                 response_future = stub.StreamingInputCall.future(
-                    _streaming_input_request_iterator(),
+                    _streaming_input_request_iterator(self._payload_pb2,
+                                                      self._requests_pb2),
                     test_constants.LONG_TIMEOUT)
             response = response_future.result()
         expected_response = methods.StreamingInputCall(
-            _streaming_input_request_iterator(), 'not a real RpcContext!')
+            _streaming_input_request_iterator(self._payload_pb2,
+                                              self._requests_pb2),
+            'not a real RpcContext!')
         self.assertEqual(expected_response, response)
 
     def testStreamingInputCallFutureExpired(self):
-        with _CreateService() as (methods, stub):
+        self._protoc()
+
+        with _CreateService(self._payload_pb2, self._responses_pb2,
+                            self._service_pb2) as (methods, stub):
             with methods.pause():
                 response_future = stub.StreamingInputCall.future(
-                    _streaming_input_request_iterator(),
+                    _streaming_input_request_iterator(self._payload_pb2,
+                                                      self._requests_pb2),
                     test_constants.SHORT_TIMEOUT)
                 with self.assertRaises(face.ExpirationError):
                     response_future.result()
@@ -363,10 +506,14 @@ class PythonPluginTest(unittest.TestCase):
                                       face.ExpirationError)
 
     def testStreamingInputCallFutureCancelled(self):
-        with _CreateService() as (methods, stub):
+        self._protoc()
+
+        with _CreateService(self._payload_pb2, self._responses_pb2,
+                            self._service_pb2) as (methods, stub):
             with methods.pause():
                 response_future = stub.StreamingInputCall.future(
-                    _streaming_input_request_iterator(),
+                    _streaming_input_request_iterator(self._payload_pb2,
+                                                      self._requests_pb2),
                     test_constants.LONG_TIMEOUT)
                 response_future.cancel()
                 self.assertTrue(response_future.cancelled())
@@ -374,26 +521,38 @@ class PythonPluginTest(unittest.TestCase):
                 response_future.result()
 
     def testStreamingInputCallFutureFailed(self):
-        with _CreateService() as (methods, stub):
+        self._protoc()
+
+        with _CreateService(self._payload_pb2, self._responses_pb2,
+                            self._service_pb2) as (methods, stub):
             with methods.fail():
                 response_future = stub.StreamingInputCall.future(
-                    _streaming_input_request_iterator(),
+                    _streaming_input_request_iterator(self._payload_pb2,
+                                                      self._requests_pb2),
                     test_constants.LONG_TIMEOUT)
                 self.assertIsNotNone(response_future.exception())
 
     def testFullDuplexCall(self):
-        with _CreateService() as (methods, stub):
-            responses = stub.FullDuplexCall(_full_duplex_request_iterator(),
-                                            test_constants.LONG_TIMEOUT)
+        self._protoc()
+
+        with _CreateService(self._payload_pb2, self._responses_pb2,
+                            self._service_pb2) as (methods, stub):
+            responses = stub.FullDuplexCall(
+                _full_duplex_request_iterator(self._requests_pb2),
+                test_constants.LONG_TIMEOUT)
             expected_responses = methods.FullDuplexCall(
-                _full_duplex_request_iterator(), 'not a real RpcContext!')
+                _full_duplex_request_iterator(self._requests_pb2),
+                'not a real RpcContext!')
             for expected_response, response in moves.zip_longest(
                     expected_responses, responses):
                 self.assertEqual(expected_response, response)
 
     def testFullDuplexCallExpired(self):
-        request_iterator = _full_duplex_request_iterator()
-        with _CreateService() as (methods, stub):
+        self._protoc()
+
+        request_iterator = _full_duplex_request_iterator(self._requests_pb2)
+        with _CreateService(self._payload_pb2, self._responses_pb2,
+                            self._service_pb2) as (methods, stub):
             with methods.pause():
                 responses = stub.FullDuplexCall(request_iterator,
                                                 test_constants.SHORT_TIMEOUT)
@@ -401,8 +560,11 @@ class PythonPluginTest(unittest.TestCase):
                     list(responses)
 
     def testFullDuplexCallCancelled(self):
-        with _CreateService() as (methods, stub):
-            request_iterator = _full_duplex_request_iterator()
+        self._protoc()
+
+        with _CreateService(self._payload_pb2, self._responses_pb2,
+                            self._service_pb2) as (methods, stub):
+            request_iterator = _full_duplex_request_iterator(self._requests_pb2)
             responses = stub.FullDuplexCall(request_iterator,
                                             test_constants.LONG_TIMEOUT)
             next(responses)
@@ -411,8 +573,11 @@ class PythonPluginTest(unittest.TestCase):
                 next(responses)
 
     def testFullDuplexCallFailed(self):
-        request_iterator = _full_duplex_request_iterator()
-        with _CreateService() as (methods, stub):
+        self._protoc()
+
+        request_iterator = _full_duplex_request_iterator(self._requests_pb2)
+        with _CreateService(self._payload_pb2, self._responses_pb2,
+                            self._service_pb2) as (methods, stub):
             with methods.fail():
                 responses = stub.FullDuplexCall(request_iterator,
                                                 test_constants.LONG_TIMEOUT)
@@ -421,13 +586,16 @@ class PythonPluginTest(unittest.TestCase):
                     next(responses)
 
     def testHalfDuplexCall(self):
-        with _CreateService() as (methods, stub):
+        self._protoc()
+
+        with _CreateService(self._payload_pb2, self._responses_pb2,
+                            self._service_pb2) as (methods, stub):
 
             def half_duplex_request_iterator():
-                request = request_pb2.StreamingOutputCallRequest()
+                request = self._requests_pb2.StreamingOutputCallRequest()
                 request.response_parameters.add(size=1, interval_us=0)
                 yield request
-                request = request_pb2.StreamingOutputCallRequest()
+                request = self._requests_pb2.StreamingOutputCallRequest()
                 request.response_parameters.add(size=2, interval_us=0)
                 request.response_parameters.add(size=3, interval_us=0)
                 yield request
@@ -441,6 +609,8 @@ class PythonPluginTest(unittest.TestCase):
                 self.assertEqual(expected_response, response)
 
     def testHalfDuplexCallWedged(self):
+        self._protoc()
+
         condition = threading.Condition()
         wait_cell = [False]
 
@@ -455,14 +625,15 @@ class PythonPluginTest(unittest.TestCase):
                 condition.notify_all()
 
         def half_duplex_request_iterator():
-            request = request_pb2.StreamingOutputCallRequest()
+            request = self._requests_pb2.StreamingOutputCallRequest()
             request.response_parameters.add(size=1, interval_us=0)
             yield request
             with condition:
                 while wait_cell[0]:
                     condition.wait()
 
-        with _CreateService() as (methods, stub):
+        with _CreateService(self._payload_pb2, self._responses_pb2,
+                            self._service_pb2) as (methods, stub):
             with wait():
                 responses = stub.HalfDuplexCall(half_duplex_request_iterator(),
                                                 test_constants.SHORT_TIMEOUT)
diff --git a/src/ruby/lib/grpc/google_rpc_status_utils.rb b/src/ruby/lib/grpc/google_rpc_status_utils.rb
new file mode 100644
index 0000000000..fdadd6b76e
--- /dev/null
+++ b/src/ruby/lib/grpc/google_rpc_status_utils.rb
@@ -0,0 +1,28 @@
+# Copyright 2017 gRPC authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+require_relative './grpc'
+require 'google/rpc/status_pb'
+
+# GRPC contains the General RPC module.
+module GRPC
+  # GoogleRpcStatusUtils provides utilities to convert between a
+  # GRPC::Core::Status and a deserialized Google::Rpc::Status proto
+  class GoogleRpcStatusUtils
+    def self.extract_google_rpc_status(status)
+      fail ArgumentError, 'bad type' unless status.is_a? Struct::Status
+      Google::Rpc::Status.decode(status.metadata['grpc-status-details-bin'])
+    end
+  end
+end
diff --git a/src/ruby/spec/google_rpc_status_utils_spec.rb b/src/ruby/spec/google_rpc_status_utils_spec.rb
new file mode 100644
index 0000000000..fe221c30dd
--- /dev/null
+++ b/src/ruby/spec/google_rpc_status_utils_spec.rb
@@ -0,0 +1,223 @@
+# Copyright 2017 gRPC authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+require 'grpc'
+require_relative '../lib/grpc/google_rpc_status_utils'
+require_relative '../pb/src/proto/grpc/testing/messages_pb'
+require_relative '../pb/src/proto/grpc/testing/messages_pb'
+require 'google/protobuf/well_known_types'
+
+include GRPC::Core
+
+describe 'conversion from a status struct to a google protobuf status' do
+  it 'fails if the input is not a status struct' do
+    begin
+      GRPC::GoogleRpcStatusUtils.extract_google_rpc_status('string')
+    rescue => e
+      exception = e
+    end
+    expect(exception.is_a?(ArgumentError)).to be true
+    expect(exception.message.include?('bad type')).to be true
+  end
+
+  it 'fails with some error if the header key is missing' do
+    status = Struct::Status.new(1, 'details', key: 'val')
+    expect(status.metadata.nil?).to be false
+    expect do
+      GRPC::GoogleRpcStatusUtils.extract_google_rpc_status(status)
+    end.to raise_error(StandardError)
+  end
+
+  it 'fails with some error if the header key fails to deserialize' do
+    status = Struct::Status.new(1, 'details',
+                                'grpc-status-details-bin' => 'string_val')
+    expect do
+      GRPC::GoogleRpcStatusUtils.extract_google_rpc_status(status)
+    end.to raise_error(StandardError)
+  end
+
+  it 'silently ignores erroneous mismatch between messages in '\
+    'status struct and protobuf status' do
+    proto = Google::Rpc::Status.new(code: 1, message: 'proto message')
+    encoded_proto = Google::Rpc::Status.encode(proto)
+    status = Struct::Status.new(1, 'struct message',
+                                'grpc-status-details-bin' => encoded_proto)
+    rpc_status = GRPC::GoogleRpcStatusUtils.extract_google_rpc_status(status)
+    expect(rpc_status).to eq(proto)
+  end
+
+  it 'silently ignores erroneous mismatch between codes in status struct '\
+    'and protobuf status' do
+    proto = Google::Rpc::Status.new(code: 1, message: 'matching message')
+    encoded_proto = Google::Rpc::Status.encode(proto)
+    status = Struct::Status.new(2, 'matching message',
+                                'grpc-status-details-bin' => encoded_proto)
+    rpc_status = GRPC::GoogleRpcStatusUtils.extract_google_rpc_status(status)
+    expect(rpc_status).to eq(proto)
+  end
+
+  it 'can succesfully convert a status struct into a google protobuf status '\
+    'when there are no rpcstatus details' do
+    proto = Google::Rpc::Status.new(code: 1, message: 'matching message')
+    encoded_proto = Google::Rpc::Status.encode(proto)
+    status = Struct::Status.new(1, 'matching message',
+                                'grpc-status-details-bin' => encoded_proto)
+    out = GRPC::GoogleRpcStatusUtils.extract_google_rpc_status(status)
+    expect(out.code).to eq(1)
+    expect(out.message).to eq('matching message')
+    expect(out.details).to eq([])
+  end
+
+  it 'can succesfully convert a status struct into a google protobuf '\
+    'status when there are multiple rpcstatus details' do
+    simple_request_any = Google::Protobuf::Any.new
+    simple_request = Grpc::Testing::SimpleRequest.new(
+      payload: Grpc::Testing::Payload.new(body: 'request'))
+    simple_request_any.pack(simple_request)
+    simple_response_any = Google::Protobuf::Any.new
+    simple_response = Grpc::Testing::SimpleResponse.new(
+      payload: Grpc::Testing::Payload.new(body: 'response'))
+    simple_response_any.pack(simple_response)
+    payload_any = Google::Protobuf::Any.new
+    payload = Grpc::Testing::Payload.new(body: 'payload')
+    payload_any.pack(payload)
+    proto = Google::Rpc::Status.new(code: 1,
+                                    message: 'matching message',
+                                    details: [
+                                      simple_request_any,
+                                      simple_response_any,
+                                      payload_any
+                                    ])
+    encoded_proto = Google::Rpc::Status.encode(proto)
+    status = Struct::Status.new(1, 'matching message',
+                                'grpc-status-details-bin' => encoded_proto)
+    out = GRPC::GoogleRpcStatusUtils.extract_google_rpc_status(status)
+    expect(out.code).to eq(1)
+    expect(out.message).to eq('matching message')
+    expect(out.details[0].unpack(
+             Grpc::Testing::SimpleRequest)).to eq(simple_request)
+    expect(out.details[1].unpack(
+             Grpc::Testing::SimpleResponse)).to eq(simple_response)
+    expect(out.details[2].unpack(
+             Grpc::Testing::Payload)).to eq(payload)
+  end
+end
+
+# Test message
+class EchoMsg
+  def self.marshal(_o)
+    ''
+  end
+
+  def self.unmarshal(_o)
+    EchoMsg.new
+  end
+end
+
+# A test service that fills in the "reserved" grpc-status-details-bin trailer,
+# for client-side testing of GoogleRpcStatus protobuf extraction from trailers.
+class GoogleRpcStatusTestService
+  include GRPC::GenericService
+  rpc :an_rpc, EchoMsg, EchoMsg
+
+  def initialize(encoded_rpc_status)
+    @encoded_rpc_status = encoded_rpc_status
+  end
+
+  def an_rpc(_, _)
+    # TODO: create a server-side utility API for sending a google rpc status.
+    # Applications are not expected to set the grpc-status-details-bin
+    # ("grpc"-fixed and reserved for library use) manually.
+    # Doing so here is only for testing of the client-side api for extracting
+    # a google rpc status, which is useful
+    # when the interacting with a server that does fill in this trailer.
+    fail GRPC::Unknown.new('test message',
+                           'grpc-status-details-bin' => @encoded_rpc_status)
+  end
+end
+
+GoogleRpcStatusTestStub = GoogleRpcStatusTestService.rpc_stub_class
+
+describe 'receving a google rpc status from a remote endpoint' do
+  def start_server(encoded_rpc_status)
+    @srv = GRPC::RpcServer.new(pool_size: 1)
+    @server_port = @srv.add_http2_port('localhost:0',
+                                       :this_port_is_insecure)
+    @srv.handle(GoogleRpcStatusTestService.new(encoded_rpc_status))
+    @server_thd = Thread.new { @srv.run }
+    @srv.wait_till_running
+  end
+
+  def stop_server
+    expect(@srv.stopped?).to be(false)
+    @srv.stop
+    @server_thd.join
+    expect(@srv.stopped?).to be(true)
+  end
+
+  before(:each) do
+    simple_request_any = Google::Protobuf::Any.new
+    simple_request = Grpc::Testing::SimpleRequest.new(
+      payload: Grpc::Testing::Payload.new(body: 'request'))
+    simple_request_any.pack(simple_request)
+    simple_response_any = Google::Protobuf::Any.new
+    simple_response = Grpc::Testing::SimpleResponse.new(
+      payload: Grpc::Testing::Payload.new(body: 'response'))
+    simple_response_any.pack(simple_response)
+    payload_any = Google::Protobuf::Any.new
+    payload = Grpc::Testing::Payload.new(body: 'payload')
+    payload_any.pack(payload)
+    @expected_proto = Google::Rpc::Status.new(
+      code: StatusCodes::UNKNOWN,
+      message: 'test message',
+      details: [simple_request_any, simple_response_any, payload_any])
+    start_server(Google::Rpc::Status.encode(@expected_proto))
+  end
+
+  after(:each) do
+    stop_server
+  end
+
+  it 'should receive be able to extract a google rpc status from the '\
+    'status struct taken from a BadStatus exception' do
+    stub = GoogleRpcStatusTestStub.new("localhost:#{@server_port}",
+                                       :this_channel_is_insecure)
+    begin
+      stub.an_rpc(EchoMsg.new)
+    rescue GRPC::BadStatus => e
+      rpc_status = GRPC::GoogleRpcStatusUtils.extract_google_rpc_status(
+        e.to_status)
+    end
+    expect(rpc_status).to eq(@expected_proto)
+  end
+
+  it 'should receive be able to extract a google rpc status from the '\
+    'status struct taken from the op view of a call' do
+    stub = GoogleRpcStatusTestStub.new("localhost:#{@server_port}",
+                                       :this_channel_is_insecure)
+    op = stub.an_rpc(EchoMsg.new, return_op: true)
+    begin
+      op.execute
+    rescue GRPC::BadStatus => e
+      status_from_exception = e.to_status
+    end
+    rpc_status = GRPC::GoogleRpcStatusUtils.extract_google_rpc_status(
+      op.status)
+    expect(rpc_status).to eq(@expected_proto)
+    # "to_status" on the bad status should give the same result
+    # as "status" on the "op view".
+    expect(GRPC::GoogleRpcStatusUtils.extract_google_rpc_status(
+             status_from_exception)).to eq(rpc_status)
+  end
+end
diff --git a/templates/config.m4.template b/templates/config.m4.template
index f91893c2bd..cd93fbd0fb 100644
--- a/templates/config.m4.template
+++ b/templates/config.m4.template
@@ -14,7 +14,7 @@
     LIBS="-lpthread $LIBS"
 
     CFLAGS="-Wall -Werror -Wno-parentheses-equality -Wno-unused-value -std=c11"
-    CXXFLAGS="-std=c++11"
+    CXXFLAGS="-std=c++11 -fno-exceptions -fno-rtti"
     GRPC_SHARED_LIBADD="-lpthread $GRPC_SHARED_LIBADD"
     PHP_REQUIRE_CXX()
     PHP_ADD_LIBRARY(pthread)
diff --git a/templates/grpc.gemspec.template b/templates/grpc.gemspec.template
index e62e5b2721..215d5f9df9 100644
--- a/templates/grpc.gemspec.template
+++ b/templates/grpc.gemspec.template
@@ -31,6 +31,7 @@
 
     s.add_dependency 'google-protobuf', '~> 3.1'
     s.add_dependency 'googleauth',      '~> 0.5.1'
+    s.add_dependency 'googleapis-common-protos-types', '~> 1.0.0'
 
     s.add_development_dependency 'bundler',            '~> 1.9'
     s.add_development_dependency 'facter',             '~> 2.4'
diff --git a/templates/package.xml.template b/templates/package.xml.template
index 15da704a47..f10f75b8c0 100644
--- a/templates/package.xml.template
+++ b/templates/package.xml.template
@@ -12,7 +12,7 @@
     <email>grpc-packages@google.com</email>
     <active>yes</active>
    </lead>
-   <date>2017-05-22</date>
+   <date>2017-08-24</date>
    <time>16:06:07</time>
    <version>
     <release>${settings.php_version.php()}</release>
@@ -27,6 +27,9 @@
   - Channel are now by default persistent #11878
   - Some bug fixes from 1.4 branch #12109, #12123
   - Fixed hang bug when fork() was used #11814
+  - License changed to Apache 2.0
+  - Added support for php_namespace option in codegen plugin #11886
+  - Updated gRPC C Core library version 1.6
    </notes>
    <contents>
     <dir baseinstalldir="/" name="/">
diff --git a/templates/src/python/grpcio_testing/grpc_version.py.template b/templates/src/python/grpcio_testing/grpc_version.py.template
new file mode 100644
index 0000000000..74db811d60
--- /dev/null
+++ b/templates/src/python/grpcio_testing/grpc_version.py.template
@@ -0,0 +1,19 @@
+%YAML 1.2
+--- |
+  # Copyright 2017 gRPC authors.
+  #
+  # Licensed under the Apache License, Version 2.0 (the "License");
+  # you may not use this file except in compliance with the License.
+  # You may obtain a copy of the License at
+  #
+  #     http://www.apache.org/licenses/LICENSE-2.0
+  #
+  # Unless required by applicable law or agreed to in writing, software
+  # distributed under the License is distributed on an "AS IS" BASIS,
+  # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  # See the License for the specific language governing permissions and
+  # limitations under the License.
+
+  # AUTO-GENERATED FROM `$REPO_ROOT/templates/src/python/grpcio_testing/grpc_version.py.template`!!!
+
+  VERSION='${settings.python_version.pep440()}'
diff --git a/test/core/client_channel/lb_policies_test.c b/test/core/client_channel/lb_policies_test.c
index f70a9fc880..ba37cd673f 100644
--- a/test/core/client_channel/lb_policies_test.c
+++ b/test/core/client_channel/lb_policies_test.c
@@ -519,7 +519,7 @@ static grpc_channel *create_client(const servers_fixture *f) {
   arg_array[1].key = GRPC_ARG_LB_POLICY_NAME;
   arg_array[1].value.string = "ROUND_ROBIN";
   arg_array[2].type = GRPC_ARG_INTEGER;
-  arg_array[2].key = GRPC_ARG_HTTP2_MIN_TIME_BETWEEN_PINGS_MS;
+  arg_array[2].key = GRPC_ARG_HTTP2_MIN_SENT_PING_INTERVAL_WITHOUT_DATA_MS;
   arg_array[2].value.integer = 0;
   args.num_args = GPR_ARRAY_SIZE(arg_array);
   args.args = arg_array;
diff --git a/test/core/end2end/tests/bad_ping.c b/test/core/end2end/tests/bad_ping.c
index 12aceda688..c97d11b306 100644
--- a/test/core/end2end/tests/bad_ping.c
+++ b/test/core/end2end/tests/bad_ping.c
@@ -66,18 +66,19 @@ static void end_test(grpc_end2end_test_fixture *f) {
 static void test_bad_ping(grpc_end2end_test_config config) {
   grpc_end2end_test_fixture f = config.create_fixture(NULL, NULL);
   cq_verifier *cqv = cq_verifier_create(f.cq);
-  grpc_arg client_a[] = {{.type = GRPC_ARG_INTEGER,
-                          .key = GRPC_ARG_HTTP2_MIN_TIME_BETWEEN_PINGS_MS,
-                          .value.integer = 0},
-                         {.type = GRPC_ARG_INTEGER,
-                          .key = GRPC_ARG_HTTP2_MAX_PINGS_WITHOUT_DATA,
-                          .value.integer = 20},
-                         {.type = GRPC_ARG_INTEGER,
-                          .key = GRPC_ARG_HTTP2_BDP_PROBE,
-                          .value.integer = 0}};
+  grpc_arg client_a[] = {
+      {.type = GRPC_ARG_INTEGER,
+       .key = GRPC_ARG_HTTP2_MIN_SENT_PING_INTERVAL_WITHOUT_DATA_MS,
+       .value.integer = 10},
+      {.type = GRPC_ARG_INTEGER,
+       .key = GRPC_ARG_HTTP2_MAX_PINGS_WITHOUT_DATA,
+       .value.integer = 0},
+      {.type = GRPC_ARG_INTEGER,
+       .key = GRPC_ARG_HTTP2_BDP_PROBE,
+       .value.integer = 0}};
   grpc_arg server_a[] = {
       {.type = GRPC_ARG_INTEGER,
-       .key = GRPC_ARG_HTTP2_MIN_PING_INTERVAL_WITHOUT_DATA_MS,
+       .key = GRPC_ARG_HTTP2_MIN_RECV_PING_INTERVAL_WITHOUT_DATA_MS,
        .value.integer = 300000 /* 5 minutes */},
       {.type = GRPC_ARG_INTEGER,
        .key = GRPC_ARG_HTTP2_MAX_PING_STRIKES,
diff --git a/test/core/end2end/tests/keepalive_timeout.c b/test/core/end2end/tests/keepalive_timeout.c
index e0ead4ab62..8d01f23c00 100644
--- a/test/core/end2end/tests/keepalive_timeout.c
+++ b/test/core/end2end/tests/keepalive_timeout.c
@@ -106,13 +106,13 @@ static void test_keepalive_timeout(grpc_end2end_test_config config) {
                                 .value.integer = 0},
                                {.type = GRPC_ARG_INTEGER,
                                 .key = GRPC_ARG_HTTP2_BDP_PROBE,
-                                .value.integer = 1}};
+                                .value.integer = 0}};
 
-  grpc_channel_args *client_args = NULL;
-  client_args = grpc_channel_args_copy_and_add(client_args, keepalive_args, 2);
+  grpc_channel_args client_args = {.num_args = GPR_ARRAY_SIZE(keepalive_args),
+                                   .args = keepalive_args};
 
   grpc_end2end_test_fixture f =
-      begin_test(config, "keepalive_timeout", client_args, NULL);
+      begin_test(config, "keepalive_timeout", &client_args, NULL);
   cq_verifier *cqv = cq_verifier_create(f.cq);
   grpc_op ops[6];
   grpc_op *op;
@@ -216,12 +216,6 @@ static void test_keepalive_timeout(grpc_end2end_test_config config) {
   grpc_byte_buffer_destroy(response_payload);
   grpc_byte_buffer_destroy(response_payload_recv);
 
-  if (client_args != NULL) {
-    grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
-    grpc_channel_args_destroy(&exec_ctx, client_args);
-    grpc_exec_ctx_finish(&exec_ctx);
-  }
-
   end_test(&f);
   config.tear_down_data(&f);
 }
diff --git a/test/core/end2end/tests/ping.c b/test/core/end2end/tests/ping.c
index 112ad9d7d2..23c82569ba 100644
--- a/test/core/end2end/tests/ping.c
+++ b/test/core/end2end/tests/ping.c
@@ -37,15 +37,19 @@ static void test_ping(grpc_end2end_test_config config,
   grpc_connectivity_state state = GRPC_CHANNEL_IDLE;
   int i;
 
-  grpc_arg client_a[] = {{.type = GRPC_ARG_INTEGER,
-                          .key = GRPC_ARG_HTTP2_MIN_TIME_BETWEEN_PINGS_MS,
-                          .value.integer = 0},
-                         {.type = GRPC_ARG_INTEGER,
-                          .key = GRPC_ARG_HTTP2_MAX_PINGS_WITHOUT_DATA,
-                          .value.integer = 20}};
+  grpc_arg client_a[] = {
+      {.type = GRPC_ARG_INTEGER,
+       .key = GRPC_ARG_HTTP2_MIN_SENT_PING_INTERVAL_WITHOUT_DATA_MS,
+       .value.integer = 10},
+      {.type = GRPC_ARG_INTEGER,
+       .key = GRPC_ARG_HTTP2_MAX_PINGS_WITHOUT_DATA,
+       .value.integer = 0},
+      {.type = GRPC_ARG_INTEGER,
+       .key = GRPC_ARG_KEEPALIVE_PERMIT_WITHOUT_CALLS,
+       .value.integer = 1}};
   grpc_arg server_a[] = {
       {.type = GRPC_ARG_INTEGER,
-       .key = GRPC_ARG_HTTP2_MIN_PING_INTERVAL_WITHOUT_DATA_MS,
+       .key = GRPC_ARG_HTTP2_MIN_RECV_PING_INTERVAL_WITHOUT_DATA_MS,
        .value.integer = 0},
       {.type = GRPC_ARG_INTEGER,
        .key = GRPC_ARG_KEEPALIVE_PERMIT_WITHOUT_CALLS,
diff --git a/test/core/tsi/ssl_transport_security_test.c b/test/core/tsi/ssl_transport_security_test.c
index 364dfa1b73..2399b054b1 100644
--- a/test/core/tsi/ssl_transport_security_test.c
+++ b/test/core/tsi/ssl_transport_security_test.c
@@ -23,7 +23,9 @@
 #include "src/core/lib/iomgr/load_file.h"
 #include "src/core/lib/security/transport/security_connector.h"
 #include "src/core/tsi/ssl_transport_security.h"
+#include "src/core/tsi/transport_security.h"
 #include "src/core/tsi/transport_security_adapter.h"
+#include "src/core/tsi/transport_security_interface.h"
 #include "test/core/tsi/transport_security_test_lib.h"
 #include "test/core/util/test_config.h"
 
@@ -312,10 +314,10 @@ static void ssl_test_destruct(tsi_test_fixture *fixture) {
       key_cert_lib->bad_client_pem_key_cert_pair);
   gpr_free(key_cert_lib->root_cert);
   gpr_free(key_cert_lib);
-  /* Destroy others. */
-  tsi_ssl_server_handshaker_factory_destroy(
+  /* Unreference others. */
+  tsi_ssl_server_handshaker_factory_unref(
       ssl_fixture->server_handshaker_factory);
-  tsi_ssl_client_handshaker_factory_destroy(
+  tsi_ssl_client_handshaker_factory_unref(
       ssl_fixture->client_handshaker_factory);
 }
 
@@ -536,6 +538,118 @@ void ssl_tsi_test_do_round_trip_odd_buffer_size() {
   }
 }
 
+static const tsi_ssl_handshaker_factory_vtable *original_vtable;
+static bool handshaker_factory_destructor_called;
+
+static void ssl_tsi_test_handshaker_factory_destructor(
+    tsi_ssl_handshaker_factory *factory) {
+  GPR_ASSERT(factory != NULL);
+  handshaker_factory_destructor_called = true;
+  if (original_vtable != NULL && original_vtable->destroy != NULL) {
+    original_vtable->destroy(factory);
+  }
+}
+
+static tsi_ssl_handshaker_factory_vtable test_handshaker_factory_vtable = {
+    ssl_tsi_test_handshaker_factory_destructor};
+
+void test_tsi_ssl_client_handshaker_factory_refcounting() {
+  int i;
+  const char *cert_chain =
+      load_file(SSL_TSI_TEST_CREDENTIALS_DIR, "client.pem");
+
+  tsi_ssl_client_handshaker_factory *client_handshaker_factory;
+  GPR_ASSERT(tsi_create_ssl_client_handshaker_factory(
+                 NULL, cert_chain, NULL, NULL, 0, &client_handshaker_factory) ==
+             TSI_OK);
+
+  handshaker_factory_destructor_called = false;
+  original_vtable = tsi_ssl_handshaker_factory_swap_vtable(
+      (tsi_ssl_handshaker_factory *)client_handshaker_factory,
+      &test_handshaker_factory_vtable);
+
+  tsi_handshaker *handshaker[3];
+
+  for (i = 0; i < 3; ++i) {
+    GPR_ASSERT(tsi_ssl_client_handshaker_factory_create_handshaker(
+                   client_handshaker_factory, "google.com", &handshaker[i]) ==
+               TSI_OK);
+  }
+
+  tsi_handshaker_destroy(handshaker[1]);
+  GPR_ASSERT(!handshaker_factory_destructor_called);
+
+  tsi_handshaker_destroy(handshaker[0]);
+  GPR_ASSERT(!handshaker_factory_destructor_called);
+
+  tsi_ssl_client_handshaker_factory_unref(client_handshaker_factory);
+  GPR_ASSERT(!handshaker_factory_destructor_called);
+
+  tsi_handshaker_destroy(handshaker[2]);
+  GPR_ASSERT(handshaker_factory_destructor_called);
+
+  gpr_free((void *)cert_chain);
+}
+
+void test_tsi_ssl_server_handshaker_factory_refcounting() {
+  int i;
+  tsi_ssl_server_handshaker_factory *server_handshaker_factory;
+  tsi_handshaker *handshaker[3];
+  const char *cert_chain =
+      load_file(SSL_TSI_TEST_CREDENTIALS_DIR, "server0.pem");
+  tsi_ssl_pem_key_cert_pair cert_pair;
+
+  cert_pair.cert_chain = cert_chain;
+  cert_pair.private_key =
+      load_file(SSL_TSI_TEST_CREDENTIALS_DIR, "server0.key");
+
+  GPR_ASSERT(tsi_create_ssl_server_handshaker_factory(
+                 &cert_pair, 1, cert_chain, 0, NULL, NULL, 0,
+                 &server_handshaker_factory) == TSI_OK);
+
+  handshaker_factory_destructor_called = false;
+  original_vtable = tsi_ssl_handshaker_factory_swap_vtable(
+      (tsi_ssl_handshaker_factory *)server_handshaker_factory,
+      &test_handshaker_factory_vtable);
+
+  for (i = 0; i < 3; ++i) {
+    GPR_ASSERT(tsi_ssl_server_handshaker_factory_create_handshaker(
+                   server_handshaker_factory, &handshaker[i]) == TSI_OK);
+  }
+
+  tsi_handshaker_destroy(handshaker[1]);
+  GPR_ASSERT(!handshaker_factory_destructor_called);
+
+  tsi_handshaker_destroy(handshaker[0]);
+  GPR_ASSERT(!handshaker_factory_destructor_called);
+
+  tsi_ssl_server_handshaker_factory_unref(server_handshaker_factory);
+  GPR_ASSERT(!handshaker_factory_destructor_called);
+
+  tsi_handshaker_destroy(handshaker[2]);
+  GPR_ASSERT(handshaker_factory_destructor_called);
+
+  ssl_test_pem_key_cert_pair_destroy(cert_pair);
+}
+
+/* Attempting to create a handshaker factory with invalid parameters should fail
+ * but not crash. */
+void test_tsi_ssl_client_handshaker_factory_bad_params() {
+  const char *cert_chain = "This is not a valid PEM file.";
+
+  tsi_ssl_client_handshaker_factory *client_handshaker_factory;
+  GPR_ASSERT(tsi_create_ssl_client_handshaker_factory(
+                 NULL, cert_chain, NULL, NULL, 0, &client_handshaker_factory) ==
+             TSI_INVALID_ARGUMENT);
+  tsi_ssl_client_handshaker_factory_unref(client_handshaker_factory);
+}
+
+void ssl_tsi_test_handshaker_factory_internals() {
+  test_tsi_ssl_client_handshaker_factory_refcounting();
+  test_tsi_ssl_server_handshaker_factory_refcounting();
+  test_tsi_ssl_client_handshaker_factory_bad_params();
+}
+
 int main(int argc, char **argv) {
   grpc_test_init(argc, argv);
   grpc_init();
@@ -553,6 +667,7 @@ int main(int argc, char **argv) {
   ssl_tsi_test_do_handshake_alpn_client_server_ok();
   ssl_tsi_test_do_round_trip_for_all_configs();
   ssl_tsi_test_do_round_trip_odd_buffer_size();
+  ssl_tsi_test_handshaker_factory_internals();
   grpc_shutdown();
   return 0;
 }
diff --git a/tools/distrib/python/grpcio_tools/setup.py b/tools/distrib/python/grpcio_tools/setup.py
index 5c0329bff0..e0e9226211 100644
--- a/tools/distrib/python/grpcio_tools/setup.py
+++ b/tools/distrib/python/grpcio_tools/setup.py
@@ -47,7 +47,7 @@ CLASSIFIERS = [
     'Programming Language :: Python :: 3.5',
     'Programming Language :: Python :: 3.6',
     'License :: OSI Approved :: Apache Software License',
-],
+]
 
 PY3 = sys.version_info.major == 3
 
diff --git a/tools/dockerfile/distribtest/csharp_jessie_x64/Dockerfile b/tools/dockerfile/distribtest/csharp_jessie_x64/Dockerfile
index d13eecaa55..02ec4c278a 100644
--- a/tools/dockerfile/distribtest/csharp_jessie_x64/Dockerfile
+++ b/tools/dockerfile/distribtest/csharp_jessie_x64/Dockerfile
@@ -14,18 +14,15 @@
 
 FROM debian:jessie
 
-RUN apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 3FA7E0328081BFF6A14DA29AA6A19B38D3D831EF
-RUN echo "deb http://download.mono-project.com/repo/debian wheezy main" | tee /etc/apt/sources.list.d/mono-xamarin.list
+RUN apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys 3FA7E0328081BFF6A14DA29AA6A19B38D3D831EF
+RUN echo "deb http://download.mono-project.com/repo/debian jessie main" | tee /etc/apt/sources.list.d/mono-official.list
 RUN echo "deb http://download.mono-project.com/repo/debian wheezy-apache24-compat main" | tee -a /etc/apt/sources.list.d/mono-xamarin.list
 RUN echo "deb http://download.mono-project.com/repo/debian wheezy-libjpeg62-compat main" | tee -a /etc/apt/sources.list.d/mono-xamarin.list
-RUN echo "deb http://download.mono-project.com/repo/debian wheezy-libtiff-compat main" | tee -a /etc/apt/sources.list.d/mono-xamarin.list
 
 RUN apt-get update && apt-get install -y \
     mono-devel \
     ca-certificates-mono \
-    nuget
+    nuget \
+    && apt-get clean
 
-# make sure we have nuget 2.12+ (in case there's an older cached docker image)
-RUN apt-get update && apt-get install -y nuget
-
-RUN apt-get update && apt-get install -y unzip
+RUN apt-get update && apt-get install -y unzip && apt-get clean
diff --git a/tools/dockerfile/distribtest/csharp_jessie_x86/Dockerfile b/tools/dockerfile/distribtest/csharp_jessie_x86/Dockerfile
index 71845b590b..758f314572 100644
--- a/tools/dockerfile/distribtest/csharp_jessie_x86/Dockerfile
+++ b/tools/dockerfile/distribtest/csharp_jessie_x86/Dockerfile
@@ -14,18 +14,15 @@
 
 FROM 32bit/debian:jessie
 
-RUN apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 3FA7E0328081BFF6A14DA29AA6A19B38D3D831EF
-RUN echo "deb http://download.mono-project.com/repo/debian wheezy main" | tee /etc/apt/sources.list.d/mono-xamarin.list
+RUN apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys 3FA7E0328081BFF6A14DA29AA6A19B38D3D831EF
+RUN echo "deb http://download.mono-project.com/repo/debian jessie main" | tee /etc/apt/sources.list.d/mono-official.list
 RUN echo "deb http://download.mono-project.com/repo/debian wheezy-apache24-compat main" | tee -a /etc/apt/sources.list.d/mono-xamarin.list
 RUN echo "deb http://download.mono-project.com/repo/debian wheezy-libjpeg62-compat main" | tee -a /etc/apt/sources.list.d/mono-xamarin.list
-RUN echo "deb http://download.mono-project.com/repo/debian wheezy-libtiff-compat main" | tee -a /etc/apt/sources.list.d/mono-xamarin.list
 
 RUN apt-get update && apt-get install -y \
     mono-devel \
     ca-certificates-mono \
-    nuget
+    nuget \
+    && apt-get clean
 
-# make sure we have nuget 2.12+ (in case there's an older cached docker image)
-RUN apt-get update && apt-get install -y nuget
-
-RUN apt-get update && apt-get install -y unzip
+RUN apt-get update && apt-get install -y unzip && apt-get clean
diff --git a/tools/dockerfile/distribtest/csharp_ubuntu1604_x64/Dockerfile b/tools/dockerfile/distribtest/csharp_ubuntu1604_x64/Dockerfile
index 6604caa42c..0f40f18e38 100644
--- a/tools/dockerfile/distribtest/csharp_ubuntu1604_x64/Dockerfile
+++ b/tools/dockerfile/distribtest/csharp_ubuntu1604_x64/Dockerfile
@@ -17,11 +17,16 @@ FROM ubuntu:16.04
 RUN apt-get update && apt-get install -y \
     mono-devel \
     ca-certificates-mono \
-    nuget
+    nuget \
+    && apt-get clean
 
 # make sure we have nuget 2.12+ (in case there's an older cached docker image)
 RUN apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 3FA7E0328081BFF6A14DA29AA6A19B38D3D831EF
 RUN echo "deb http://download.mono-project.com/repo/debian wheezy main" | tee /etc/apt/sources.list.d/mono-xamarin.list
-RUN apt-get update && apt-get install -y nuget
+RUN apt-get update && apt-get install -y nuget && apt-get clean
 
-RUN apt-get update && apt-get install -y unzip
+# Prevent "Error: SendFailure (Error writing headers)" when fetching nuget packages
+# See https://github.com/tianon/docker-brew-ubuntu-core/issues/86
+RUN apt-get update && apt-get install -y tzdata && apt-get clean
+
+RUN apt-get update && apt-get install -y unzip && apt-get clean
diff --git a/tools/dockerfile/test/csharp_coreclr_x64/Dockerfile b/tools/dockerfile/test/csharp_coreclr_x64/Dockerfile
deleted file mode 100644
index 4ccfbc43c3..0000000000
--- a/tools/dockerfile/test/csharp_coreclr_x64/Dockerfile
+++ /dev/null
@@ -1,114 +0,0 @@
-# Copyright 2015 gRPC authors.
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-
-FROM debian:jessie
-
-# Install Git and basic packages.
-RUN apt-get update && apt-get install -y \
-  autoconf \
-  autotools-dev \
-  build-essential \
-  bzip2 \
-  ccache \
-  curl \
-  gcc \
-  gcc-multilib \
-  git \
-  golang \
-  gyp \
-  lcov \
-  libc6 \
-  libc6-dbg \
-  libc6-dev \
-  libgtest-dev \
-  libtool \
-  make \
-  perl \
-  strace \
-  python-dev \
-  python-setuptools \
-  python-yaml \
-  telnet \
-  unzip \
-  wget \
-  zip && apt-get clean
-
-#================
-# Build profiling
-RUN apt-get update && apt-get install -y time && apt-get clean
-
-#====================
-# Python dependencies
-
-# Install dependencies
-
-RUN apt-get update && apt-get install -y \
-    python-all-dev \
-    python3-all-dev \
-    python-pip
-
-# Install Python packages from PyPI
-RUN pip install pip --upgrade
-RUN pip install virtualenv
-RUN pip install futures==2.2.0 enum34==1.0.4 protobuf==3.2.0 six==1.10.0
-
-#================
-# C# dependencies
-
-# Update to a newer version of mono
-RUN apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys 3FA7E0328081BFF6A14DA29AA6A19B38D3D831EF
-RUN echo "deb http://download.mono-project.com/repo/debian jessie main" | tee /etc/apt/sources.list.d/mono-official.list
-RUN echo "deb http://download.mono-project.com/repo/debian wheezy-apache24-compat main" | tee -a /etc/apt/sources.list.d/mono-xamarin.list
-RUN echo "deb http://download.mono-project.com/repo/debian wheezy-libjpeg62-compat main" | tee -a /etc/apt/sources.list.d/mono-xamarin.list
-
-# Install dependencies
-RUN apt-get update && apt-get -y dist-upgrade && apt-get install -y \
-    mono-devel \
-    ca-certificates-mono \
-    nuget \
-    && apt-get clean
-
-RUN nuget update -self
-
-# Install dotnet SDK based on https://www.microsoft.com/net/core#debian
-RUN apt-get update && apt-get install -y curl libunwind8 gettext
-# dotnet-dev-1.0.0-preview2-003131
-RUN curl -sSL -o dotnet100.tar.gz https://go.microsoft.com/fwlink/?LinkID=827530
-RUN mkdir -p /opt/dotnet && tar zxf dotnet100.tar.gz -C /opt/dotnet
-# dotnet-dev-1.0.1
-RUN curl -sSL -o dotnet101.tar.gz https://go.microsoft.com/fwlink/?LinkID=843453
-RUN mkdir -p /opt/dotnet && tar zxf dotnet101.tar.gz -C /opt/dotnet
-RUN ln -s /opt/dotnet/dotnet /usr/local/bin
-
-# Trigger the population of the local package cache
-ENV NUGET_XMLDOC_MODE skip
-RUN mkdir warmup \
-    && cd warmup \
-    && dotnet new \
-    && cd .. \
-    && rm -rf warmup
-
-# Prepare ccache
-RUN ln -s /usr/bin/ccache /usr/local/bin/gcc
-RUN ln -s /usr/bin/ccache /usr/local/bin/g++
-RUN ln -s /usr/bin/ccache /usr/local/bin/cc
-RUN ln -s /usr/bin/ccache /usr/local/bin/c++
-RUN ln -s /usr/bin/ccache /usr/local/bin/clang
-RUN ln -s /usr/bin/ccache /usr/local/bin/clang++
-
-
-RUN mkdir /var/local/jenkins
-
-# Define the default command.
-CMD ["bash"]
diff --git a/tools/internal_ci/linux/pull_request/grpc_basictests_c_dbg.cfg b/tools/internal_ci/linux/pull_request/grpc_basictests_c_dbg.cfg
new file mode 100644
index 0000000000..577cb28ae5
--- /dev/null
+++ b/tools/internal_ci/linux/pull_request/grpc_basictests_c_dbg.cfg
@@ -0,0 +1,30 @@
+# Copyright 2017 gRPC authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# Config file for the internal CI (in protobuf text format)
+
+# Location of the continuous shell script in repository.
+build_file: "grpc/tools/internal_ci/linux/grpc_run_tests_matrix.sh"
+timeout_mins: 240
+action {
+  define_artifacts {
+    regex: "**/*sponge_log.xml"
+    regex: "github/grpc/reports/**"
+  }
+}
+
+env_vars {
+  key: "RUN_TESTS_FLAGS"
+  value: "-f basictests linux c dbg --inner_jobs 16 -j 1 --internal_ci --max_time=3600"
+}
diff --git a/tools/internal_ci/linux/pull_request/grpc_basictests_c_opt.cfg b/tools/internal_ci/linux/pull_request/grpc_basictests_c_opt.cfg
new file mode 100644
index 0000000000..9e0b724b2e
--- /dev/null
+++ b/tools/internal_ci/linux/pull_request/grpc_basictests_c_opt.cfg
@@ -0,0 +1,30 @@
+# Copyright 2017 gRPC authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# Config file for the internal CI (in protobuf text format)
+
+# Location of the continuous shell script in repository.
+build_file: "grpc/tools/internal_ci/linux/grpc_run_tests_matrix.sh"
+timeout_mins: 240
+action {
+  define_artifacts {
+    regex: "**/*sponge_log.xml"
+    regex: "github/grpc/reports/**"
+  }
+}
+
+env_vars {
+  key: "RUN_TESTS_FLAGS"
+  value: "-f basictests linux c opt --inner_jobs 16 -j 1 --internal_ci --max_time=3600"
+}
diff --git a/tools/internal_ci/linux/pull_request/grpc_basictests_cpp_dbg.cfg b/tools/internal_ci/linux/pull_request/grpc_basictests_cpp_dbg.cfg
new file mode 100644
index 0000000000..0fda74cf44
--- /dev/null
+++ b/tools/internal_ci/linux/pull_request/grpc_basictests_cpp_dbg.cfg
@@ -0,0 +1,30 @@
+# Copyright 2017 gRPC authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# Config file for the internal CI (in protobuf text format)
+
+# Location of the continuous shell script in repository.
+build_file: "grpc/tools/internal_ci/linux/grpc_run_tests_matrix.sh"
+timeout_mins: 240
+action {
+  define_artifacts {
+    regex: "**/*sponge_log.xml"
+    regex: "github/grpc/reports/**"
+  }
+}
+
+env_vars {
+  key: "RUN_TESTS_FLAGS"
+  value: "-f basictests linux c++ dbg --inner_jobs 16 -j 1 --internal_ci --max_time=3600"
+}
diff --git a/tools/internal_ci/linux/pull_request/grpc_basictests_cpp_opt.cfg b/tools/internal_ci/linux/pull_request/grpc_basictests_cpp_opt.cfg
new file mode 100644
index 0000000000..199a8905d9
--- /dev/null
+++ b/tools/internal_ci/linux/pull_request/grpc_basictests_cpp_opt.cfg
@@ -0,0 +1,30 @@
+# Copyright 2017 gRPC authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# Config file for the internal CI (in protobuf text format)
+
+# Location of the continuous shell script in repository.
+build_file: "grpc/tools/internal_ci/linux/grpc_run_tests_matrix.sh"
+timeout_mins: 240
+action {
+  define_artifacts {
+    regex: "**/*sponge_log.xml"
+    regex: "github/grpc/reports/**"
+  }
+}
+
+env_vars {
+  key: "RUN_TESTS_FLAGS"
+  value: "-f basictests linux c++ opt --inner_jobs 16 -j 1 --internal_ci --max_time=3600"
+}
diff --git a/tools/run_tests/artifacts/artifact_targets.py b/tools/run_tests/artifacts/artifact_targets.py
index 12263282ae..2cc0dfceab 100644
--- a/tools/run_tests/artifacts/artifact_targets.py
+++ b/tools/run_tests/artifacts/artifact_targets.py
@@ -158,6 +158,7 @@ class PythonArtifact:
       return create_jobspec(self.name,
                             ['tools/run_tests/artifacts/build_artifact_python.sh'],
                             environ=environ,
+                            timeout_seconds=60*60,
                             use_workspace=True)
 
   def __str__(self):
diff --git a/tools/run_tests/artifacts/distribtest_targets.py b/tools/run_tests/artifacts/distribtest_targets.py
index fb1be383cd..797ed51c7f 100644
--- a/tools/run_tests/artifacts/distribtest_targets.py
+++ b/tools/run_tests/artifacts/distribtest_targets.py
@@ -105,7 +105,9 @@ class CSharpDistribTest(object):
           use_workspace=True)
     elif self.platform == 'windows':
       if self.arch == 'x64':
-        environ={'MSBUILD_EXTRA_ARGS': '/p:Platform=x64',
+        # Use double leading / as the first occurence gets removed by msys bash
+        # when invoking the .bat file (side-effect of posix path conversion)
+        environ={'MSBUILD_EXTRA_ARGS': '//p:Platform=x64',
                  'DISTRIBTEST_OUTPATH': 'DistribTest\\bin\\x64\\Debug'}
       else:
         environ={'DISTRIBTEST_OUTPATH': 'DistribTest\\bin\\Debug'}
diff --git a/tools/run_tests/artifacts/package_targets.py b/tools/run_tests/artifacts/package_targets.py
index 0da13864f0..671d0f7b45 100644
--- a/tools/run_tests/artifacts/package_targets.py
+++ b/tools/run_tests/artifacts/package_targets.py
@@ -78,7 +78,7 @@ class CSharpPackage:
     if self.linux:
       return create_docker_jobspec(
           self.name,
-          'tools/dockerfile/test/csharp_coreclr_x64',
+          'tools/dockerfile/test/csharp_jessie_x64',
           'src/csharp/build_packages_dotnetcli.sh')
     else:
       return create_jobspec(self.name,