Merge branch 'master' into packet-coalescing-core

17 files changed, 210 insertions, 237 deletions

diff --git a/src/core/ext/census/grpc_filter.c b/src/core/ext/census/grpc_filter.c
index 3e8acc85e1..8e4d4732b8 100644
--- a/src/core/ext/census/grpc_filter.c
+++ b/src/core/ext/census/grpc_filter.c
@@ -154,7 +154,8 @@ static grpc_error *server_init_call_elem(grpc_exec_ctx *exec_ctx,
   memset(d, 0, sizeof(*d));
   d->start_ts = args->start_time;
   /* TODO(hongyu): call census_tracing_start_op here. */
-  grpc_closure_init(&d->finish_recv, server_on_done_recv, elem);
+  grpc_closure_init(&d->finish_recv, server_on_done_recv, elem,
+                    grpc_schedule_on_exec_ctx);
   return GRPC_ERROR_NONE;
 }
 
diff --git a/src/core/ext/client_channel/channel_connectivity.c b/src/core/ext/client_channel/channel_connectivity.c
index 9797e66564..b10f444b63 100644
--- a/src/core/ext/client_channel/channel_connectivity.c
+++ b/src/core/ext/client_channel/channel_connectivity.c
@@ -198,7 +198,8 @@ void grpc_channel_watch_connectivity_state(
   grpc_cq_begin_op(cq, tag);
 
   gpr_mu_init(&w->mu);
-  grpc_closure_init(&w->on_complete, watch_complete, w);
+  grpc_closure_init(&w->on_complete, watch_complete, w,
+                    grpc_schedule_on_exec_ctx);
   w->phase = WAITING;
   w->state = last_observed_state;
   w->cq = cq;
diff --git a/src/core/ext/client_channel/client_channel.c b/src/core/ext/client_channel/client_channel.c
index 9d46338428..a762b8917e 100644
--- a/src/core/ext/client_channel/client_channel.c
+++ b/src/core/ext/client_channel/client_channel.c
@@ -249,7 +249,8 @@ static void watch_lb_policy(grpc_exec_ctx *exec_ctx, channel_data *chand,
   GRPC_CHANNEL_STACK_REF(chand->owning_stack, "watch_lb_policy");
 
   w->chand = chand;
-  grpc_closure_init(&w->on_changed, on_lb_policy_state_changed, w);
+  grpc_closure_init(&w->on_changed, on_lb_policy_state_changed, w,
+                    grpc_schedule_on_exec_ctx);
   w->state = current_state;
   w->lb_policy = lb_policy;
   grpc_lb_policy_notify_on_state_change(exec_ctx, lb_policy, &w->state,
@@ -361,14 +362,12 @@ static void on_resolver_result_changed(grpc_exec_ctx *exec_ctx, void *arg,
   }
   chand->method_params_table = method_params_table;
   if (lb_policy != NULL) {
-    grpc_exec_ctx_enqueue_list(exec_ctx, &chand->waiting_for_config_closures,
-                               NULL);
+    grpc_closure_list_sched(exec_ctx, &chand->waiting_for_config_closures);
   } else if (chand->resolver == NULL /* disconnected */) {
     grpc_closure_list_fail_all(
         &chand->waiting_for_config_closures,
         GRPC_ERROR_CREATE_REFERENCING("Channel disconnected", &error, 1));
-    grpc_exec_ctx_enqueue_list(exec_ctx, &chand->waiting_for_config_closures,
-                               NULL);
+    grpc_closure_list_sched(exec_ctx, &chand->waiting_for_config_closures);
   }
   if (lb_policy != NULL && chand->exit_idle_when_lb_policy_arrives) {
     GRPC_LB_POLICY_REF(lb_policy, "exit_idle");
@@ -425,7 +424,7 @@ static void cc_start_transport_op(grpc_exec_ctx *exec_ctx,
                                   grpc_transport_op *op) {
   channel_data *chand = elem->channel_data;
 
-  grpc_exec_ctx_sched(exec_ctx, op->on_consumed, GRPC_ERROR_NONE, NULL);
+  grpc_closure_sched(exec_ctx, op->on_consumed, GRPC_ERROR_NONE);
 
   GPR_ASSERT(op->set_accept_stream == false);
   if (op->bind_pollset != NULL) {
@@ -444,9 +443,8 @@ static void cc_start_transport_op(grpc_exec_ctx *exec_ctx,
 
   if (op->send_ping != NULL) {
     if (chand->lb_policy == NULL) {
-      grpc_exec_ctx_sched(exec_ctx, op->send_ping,
-                          GRPC_ERROR_CREATE("Ping with no load balancing"),
-                          NULL);
+      grpc_closure_sched(exec_ctx, op->send_ping,
+                         GRPC_ERROR_CREATE("Ping with no load balancing"));
     } else {
       grpc_lb_policy_ping_one(exec_ctx, chand->lb_policy, op->send_ping);
       op->bind_pollset = NULL;
@@ -465,8 +463,7 @@ static void cc_start_transport_op(grpc_exec_ctx *exec_ctx,
       if (!chand->started_resolving) {
         grpc_closure_list_fail_all(&chand->waiting_for_config_closures,
                                    GRPC_ERROR_REF(op->disconnect_with_error));
-        grpc_exec_ctx_enqueue_list(exec_ctx,
-                                   &chand->waiting_for_config_closures, NULL);
+        grpc_closure_list_sched(exec_ctx, &chand->waiting_for_config_closures);
       }
       if (chand->lb_policy != NULL) {
         grpc_pollset_set_del_pollset_set(exec_ctx,
@@ -511,7 +508,8 @@ static grpc_error *cc_init_channel_elem(grpc_exec_ctx *exec_ctx,
   gpr_mu_init(&chand->mu);
   chand->owning_stack = args->channel_stack;
   grpc_closure_init(&chand->on_resolver_result_changed,
-                    on_resolver_result_changed, chand);
+                    on_resolver_result_changed, chand,
+                    grpc_schedule_on_exec_ctx);
   chand->interested_parties = grpc_pollset_set_create();
   grpc_connectivity_state_init(&chand->state_tracker, GRPC_CHANNEL_IDLE,
                                "client_channel");
@@ -678,8 +676,9 @@ static void retry_waiting_locked(grpc_exec_ctx *exec_ctx, call_data *calld) {
   calld->waiting_ops_count = 0;
   calld->waiting_ops_capacity = 0;
   GRPC_SUBCHANNEL_CALL_REF(a->call, "retry_ops");
-  grpc_exec_ctx_sched(exec_ctx, grpc_closure_create(retry_ops, a),
-                      GRPC_ERROR_NONE, NULL);
+  grpc_closure_sched(
+      exec_ctx, grpc_closure_create(retry_ops, a, grpc_schedule_on_exec_ctx),
+      GRPC_ERROR_NONE);
 }
 
 static void subchannel_ready(grpc_exec_ctx *exec_ctx, void *arg,
@@ -761,14 +760,14 @@ static void continue_picking(grpc_exec_ctx *exec_ctx, void *arg,
   if (cpa->connected_subchannel == NULL) {
     /* cancelled, do nothing */
   } else if (error != GRPC_ERROR_NONE) {
-    grpc_exec_ctx_sched(exec_ctx, cpa->on_ready, GRPC_ERROR_REF(error), NULL);
+    grpc_closure_sched(exec_ctx, cpa->on_ready, GRPC_ERROR_REF(error));
   } else {
     call_data *calld = cpa->elem->call_data;
     gpr_mu_lock(&calld->mu);
     if (pick_subchannel(exec_ctx, cpa->elem, cpa->initial_metadata,
                         cpa->initial_metadata_flags, cpa->connected_subchannel,
                         cpa->on_ready, GRPC_ERROR_NONE)) {
-      grpc_exec_ctx_sched(exec_ctx, cpa->on_ready, GRPC_ERROR_NONE, NULL);
+      grpc_closure_sched(exec_ctx, cpa->on_ready, GRPC_ERROR_NONE);
     }
     gpr_mu_unlock(&calld->mu);
   }
@@ -800,9 +799,9 @@ static bool pick_subchannel(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
       cpa = closure->cb_arg;
       if (cpa->connected_subchannel == connected_subchannel) {
         cpa->connected_subchannel = NULL;
-        grpc_exec_ctx_sched(
+        grpc_closure_sched(
             exec_ctx, cpa->on_ready,
-            GRPC_ERROR_CREATE_REFERENCING("Pick cancelled", &error, 1), NULL);
+            GRPC_ERROR_CREATE_REFERENCING("Pick cancelled", &error, 1));
       }
     }
     gpr_mu_unlock(&chand->mu);
@@ -853,12 +852,12 @@ static bool pick_subchannel(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
     cpa->connected_subchannel = connected_subchannel;
     cpa->on_ready = on_ready;
     cpa->elem = elem;
-    grpc_closure_init(&cpa->closure, continue_picking, cpa);
+    grpc_closure_init(&cpa->closure, continue_picking, cpa,
+                      grpc_schedule_on_exec_ctx);
     grpc_closure_list_append(&chand->waiting_for_config_closures, &cpa->closure,
                              GRPC_ERROR_NONE);
   } else {
-    grpc_exec_ctx_sched(exec_ctx, on_ready, GRPC_ERROR_CREATE("Disconnected"),
-                        NULL);
+    grpc_closure_sched(exec_ctx, on_ready, GRPC_ERROR_CREATE("Disconnected"));
   }
   gpr_mu_unlock(&chand->mu);
 
@@ -943,7 +942,8 @@ retry:
       calld->connected_subchannel == NULL &&
       op->send_initial_metadata != NULL) {
     calld->creation_phase = GRPC_SUBCHANNEL_CALL_HOLDER_PICKING_SUBCHANNEL;
-    grpc_closure_init(&calld->next_step, subchannel_ready, elem);
+    grpc_closure_init(&calld->next_step, subchannel_ready, elem,
+                      grpc_schedule_on_exec_ctx);
     GRPC_CALL_STACK_REF(calld->owning_call, "pick_subchannel");
     /* If a subchannel is not available immediately, the polling entity from
        call_data should be provided to channel_data's interested_parties, so
@@ -1089,7 +1089,8 @@ static grpc_error *cc_init_call_elem(grpc_exec_ctx *exec_ctx,
     // get the service config data once the resolver returns.
     // Take a reference to the call stack to be owned by the callback.
     GRPC_CALL_STACK_REF(calld->owning_call, "read_service_config");
-    grpc_closure_init(&calld->read_service_config, read_service_config, elem);
+    grpc_closure_init(&calld->read_service_config, read_service_config, elem,
+                      grpc_schedule_on_exec_ctx);
     grpc_closure_list_append(&chand->waiting_for_config_closures,
                              &calld->read_service_config, GRPC_ERROR_NONE);
     gpr_mu_unlock(&chand->mu);
@@ -1202,7 +1203,8 @@ void grpc_client_channel_watch_connectivity_state(
   w->pollset = pollset;
   w->on_complete = on_complete;
   grpc_pollset_set_add_pollset(exec_ctx, chand->interested_parties, pollset);
-  grpc_closure_init(&w->my_closure, on_external_watch_complete, w);
+  grpc_closure_init(&w->my_closure, on_external_watch_complete, w,
+                    grpc_schedule_on_exec_ctx);
   GRPC_CHANNEL_STACK_REF(w->chand->owning_stack,
                          "external_connectivity_watcher");
   gpr_mu_lock(&chand->mu);
diff --git a/src/core/ext/client_channel/http_connect_handshaker.c b/src/core/ext/client_channel/http_connect_handshaker.c
index 76c78ee853..a0fc95e7bb 100644
--- a/src/core/ext/client_channel/http_connect_handshaker.c
+++ b/src/core/ext/client_channel/http_connect_handshaker.c
@@ -131,7 +131,7 @@ static void handshake_failed_locked(grpc_exec_ctx* exec_ctx,
     handshaker->shutdown = true;
   }
   // Invoke callback.
-  grpc_exec_ctx_sched(exec_ctx, handshaker->on_handshake_done, error, NULL);
+  grpc_closure_sched(exec_ctx, handshaker->on_handshake_done, error);
 }
 
 // Callback invoked when finished writing HTTP CONNECT request.
@@ -229,7 +229,7 @@ static void on_read_done(grpc_exec_ctx* exec_ctx, void* arg,
     goto done;
   }
   // Success.  Invoke handshake-done callback.
-  grpc_exec_ctx_sched(exec_ctx, handshaker->on_handshake_done, error, NULL);
+  grpc_closure_sched(exec_ctx, handshaker->on_handshake_done, error);
 done:
   // Set shutdown to true so that subsequent calls to
   // http_connect_handshaker_shutdown() do nothing.
@@ -313,9 +313,9 @@ grpc_handshaker* grpc_http_connect_handshaker_create(const char* proxy_server) {
   handshaker->proxy_server = gpr_strdup(proxy_server);
   grpc_slice_buffer_init(&handshaker->write_buffer);
   grpc_closure_init(&handshaker->request_done_closure, on_write_done,
-                    handshaker);
+                    handshaker, grpc_schedule_on_exec_ctx);
   grpc_closure_init(&handshaker->response_read_closure, on_read_done,
-                    handshaker);
+                    handshaker, grpc_schedule_on_exec_ctx);
   grpc_http_parser_init(&handshaker->http_parser, GRPC_HTTP_RESPONSE,
                         &handshaker->http_response);
   return &handshaker->base;
diff --git a/src/core/ext/client_channel/subchannel.c b/src/core/ext/client_channel/subchannel.c
index f294e69392..87f0ef298a 100644
--- a/src/core/ext/client_channel/subchannel.c
+++ b/src/core/ext/client_channel/subchannel.c
@@ -293,8 +293,9 @@ void grpc_subchannel_weak_unref(grpc_exec_ctx *exec_ctx,
   gpr_atm old_refs;
   old_refs = ref_mutate(c, -(gpr_atm)1, 1 REF_MUTATE_PURPOSE("WEAK_UNREF"));
   if (old_refs == 1) {
-    grpc_exec_ctx_sched(exec_ctx, grpc_closure_create(subchannel_destroy, c),
-                        GRPC_ERROR_NONE, NULL);
+    grpc_closure_sched(exec_ctx, grpc_closure_create(subchannel_destroy, c,
+                                                     grpc_schedule_on_exec_ctx),
+                       GRPC_ERROR_NONE);
   }
 }
 
@@ -330,7 +331,8 @@ grpc_subchannel *grpc_subchannel_create(grpc_exec_ctx *exec_ctx,
   c->args = grpc_channel_args_copy(args->args);
   c->root_external_state_watcher.next = c->root_external_state_watcher.prev =
       &c->root_external_state_watcher;
-  grpc_closure_init(&c->connected, subchannel_connected, c);
+  grpc_closure_init(&c->connected, subchannel_connected, c,
+                    grpc_schedule_on_exec_ctx);
   grpc_connectivity_state_init(&c->state_tracker, GRPC_CHANNEL_IDLE,
                                "subchannel");
   int initial_backoff_ms =
@@ -505,7 +507,8 @@ void grpc_subchannel_notify_on_state_change(
     w->subchannel = c;
     w->pollset_set = interested_parties;
     w->notify = notify;
-    grpc_closure_init(&w->closure, on_external_state_watcher_done, w);
+    grpc_closure_init(&w->closure, on_external_state_watcher_done, w,
+                      grpc_schedule_on_exec_ctx);
     if (interested_parties != NULL) {
       grpc_pollset_set_add_pollset_set(exec_ctx, c->pollset_set,
                                        interested_parties);
@@ -626,7 +629,7 @@ static void publish_transport_locked(grpc_exec_ctx *exec_ctx,
   sw_subchannel->subchannel = c;
   sw_subchannel->connectivity_state = GRPC_CHANNEL_READY;
   grpc_closure_init(&sw_subchannel->closure, subchannel_on_child_state_changed,
-                    sw_subchannel);
+                    sw_subchannel, grpc_schedule_on_exec_ctx);
 
   if (c->disconnected) {
     gpr_free(sw_subchannel);
diff --git a/src/core/ext/lb_policy/grpclb/grpclb.c b/src/core/ext/lb_policy/grpclb/grpclb.c
index bed5e6c901..bb0ee9d95c 100644
--- a/src/core/ext/lb_policy/grpclb/grpclb.c
+++ b/src/core/ext/lb_policy/grpclb/grpclb.c
@@ -180,8 +180,7 @@ static void wrapped_rr_closure(grpc_exec_ctx *exec_ctx, void *arg,
   wrapped_rr_closure_arg *wc_arg = arg;
 
   GPR_ASSERT(wc_arg->wrapped_closure != NULL);
-  grpc_exec_ctx_sched(exec_ctx, wc_arg->wrapped_closure, GRPC_ERROR_REF(error),
-                      NULL);
+  grpc_closure_sched(exec_ctx, wc_arg->wrapped_closure, GRPC_ERROR_REF(error));
 
   if (wc_arg->rr_policy != NULL) {
     /* if *target is NULL, no pick has been made by the RR policy (eg, all
@@ -248,7 +247,8 @@ static void add_pending_pick(pending_pick **root,
       pick_args->lb_token_mdelem_storage;
   pp->wrapped_on_complete_arg.free_when_done = pp;
   grpc_closure_init(&pp->wrapped_on_complete_arg.wrapper_closure,
-                    wrapped_rr_closure, &pp->wrapped_on_complete_arg);
+                    wrapped_rr_closure, &pp->wrapped_on_complete_arg,
+                    grpc_schedule_on_exec_ctx);
   *root = pp;
 }
 
@@ -268,7 +268,8 @@ static void add_pending_ping(pending_ping **root, grpc_closure *notify) {
   pping->wrapped_notify_arg.free_when_done = pping;
   pping->next = *root;
   grpc_closure_init(&pping->wrapped_notify_arg.wrapper_closure,
-                    wrapped_rr_closure, &pping->wrapped_notify_arg);
+                    wrapped_rr_closure, &pping->wrapped_notify_arg,
+                    grpc_schedule_on_exec_ctx);
   *root = pping;
 }
 
@@ -667,7 +668,7 @@ static void rr_handover_locked(grpc_exec_ctx *exec_ctx,
       gpr_malloc(sizeof(rr_connectivity_data));
   memset(rr_connectivity, 0, sizeof(rr_connectivity_data));
   grpc_closure_init(&rr_connectivity->on_change, glb_rr_connectivity_changed,
-                    rr_connectivity);
+                    rr_connectivity, grpc_schedule_on_exec_ctx);
   rr_connectivity->glb_policy = glb_policy;
   rr_connectivity->state = new_rr_state;
 
@@ -908,15 +909,15 @@ static void glb_shutdown(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol) {
   while (pp != NULL) {
     pending_pick *next = pp->next;
     *pp->target = NULL;
-    grpc_exec_ctx_sched(exec_ctx, &pp->wrapped_on_complete_arg.wrapper_closure,
-                        GRPC_ERROR_NONE, NULL);
+    grpc_closure_sched(exec_ctx, &pp->wrapped_on_complete_arg.wrapper_closure,
+                       GRPC_ERROR_NONE);
     pp = next;
   }
 
   while (pping != NULL) {
     pending_ping *next = pping->next;
-    grpc_exec_ctx_sched(exec_ctx, &pping->wrapped_notify_arg.wrapper_closure,
-                        GRPC_ERROR_NONE, NULL);
+    grpc_closure_sched(exec_ctx, &pping->wrapped_notify_arg.wrapper_closure,
+                       GRPC_ERROR_NONE);
     pping = next;
   }
 }
@@ -932,9 +933,9 @@ static void glb_cancel_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
     pending_pick *next = pp->next;
     if (pp->target == target) {
       *target = NULL;
-      grpc_exec_ctx_sched(
+      grpc_closure_sched(
           exec_ctx, &pp->wrapped_on_complete_arg.wrapper_closure,
-          GRPC_ERROR_CREATE_REFERENCING("Pick Cancelled", &error, 1), NULL);
+          GRPC_ERROR_CREATE_REFERENCING("Pick Cancelled", &error, 1));
     } else {
       pp->next = glb_policy->pending_picks;
       glb_policy->pending_picks = pp;
@@ -957,9 +958,9 @@ static void glb_cancel_picks(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
     pending_pick *next = pp->next;
     if ((pp->pick_args.initial_metadata_flags & initial_metadata_flags_mask) ==
         initial_metadata_flags_eq) {
-      grpc_exec_ctx_sched(
+      grpc_closure_sched(
           exec_ctx, &pp->wrapped_on_complete_arg.wrapper_closure,
-          GRPC_ERROR_CREATE_REFERENCING("Pick Cancelled", &error, 1), NULL);
+          GRPC_ERROR_CREATE_REFERENCING("Pick Cancelled", &error, 1));
     } else {
       pp->next = glb_policy->pending_picks;
       glb_policy->pending_picks = pp;
@@ -994,11 +995,10 @@ static int glb_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
                     grpc_closure *on_complete) {
   if (pick_args->lb_token_mdelem_storage == NULL) {
     *target = NULL;
-    grpc_exec_ctx_sched(
+    grpc_closure_sched(
         exec_ctx, on_complete,
         GRPC_ERROR_CREATE("No mdelem storage for the LB token. Load reporting "
-                          "won't work without it. Failing"),
-        NULL);
+                          "won't work without it. Failing"));
     return 0;
   }
 
@@ -1017,7 +1017,8 @@ static int glb_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
     wrapped_rr_closure_arg *wc_arg = gpr_malloc(sizeof(wrapped_rr_closure_arg));
     memset(wc_arg, 0, sizeof(wrapped_rr_closure_arg));
 
-    grpc_closure_init(&wc_arg->wrapper_closure, wrapped_rr_closure, wc_arg);
+    grpc_closure_init(&wc_arg->wrapper_closure, wrapped_rr_closure, wc_arg,
+                      grpc_schedule_on_exec_ctx);
     wc_arg->rr_policy = glb_policy->rr_policy;
     wc_arg->target = target;
     wc_arg->wrapped_closure = on_complete;
@@ -1117,9 +1118,11 @@ static void lb_call_init_locked(glb_lb_policy *glb_policy) {
   glb_policy->lb_call_status_details_capacity = 0;
 
   grpc_closure_init(&glb_policy->lb_on_server_status_received,
-                    lb_on_server_status_received, glb_policy);
+                    lb_on_server_status_received, glb_policy,
+                    grpc_schedule_on_exec_ctx);
   grpc_closure_init(&glb_policy->lb_on_response_received,
-                    lb_on_response_received, glb_policy);
+                    lb_on_response_received, glb_policy,
+                    grpc_schedule_on_exec_ctx);
 
   gpr_backoff_init(&glb_policy->lb_call_backoff_state,
                    GRPC_GRPCLB_INITIAL_CONNECT_BACKOFF_SECONDS,
diff --git a/src/core/ext/lb_policy/pick_first/pick_first.c b/src/core/ext/lb_policy/pick_first/pick_first.c
index b9cfe6b5c0..821becff69 100644
--- a/src/core/ext/lb_policy/pick_first/pick_first.c
+++ b/src/core/ext/lb_policy/pick_first/pick_first.c
@@ -120,7 +120,7 @@ static void pf_shutdown(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol) {
   while (pp != NULL) {
     pending_pick *next = pp->next;
     *pp->target = NULL;
-    grpc_exec_ctx_sched(exec_ctx, pp->on_complete, GRPC_ERROR_NONE, NULL);
+    grpc_closure_sched(exec_ctx, pp->on_complete, GRPC_ERROR_NONE);
     gpr_free(pp);
     pp = next;
   }
@@ -138,9 +138,9 @@ static void pf_cancel_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
     pending_pick *next = pp->next;
     if (pp->target == target) {
       *target = NULL;
-      grpc_exec_ctx_sched(
+      grpc_closure_sched(
           exec_ctx, pp->on_complete,
-          GRPC_ERROR_CREATE_REFERENCING("Pick Cancelled", &error, 1), NULL);
+          GRPC_ERROR_CREATE_REFERENCING("Pick Cancelled", &error, 1));
       gpr_free(pp);
     } else {
       pp->next = p->pending_picks;
@@ -165,9 +165,9 @@ static void pf_cancel_picks(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
     pending_pick *next = pp->next;
     if ((pp->initial_metadata_flags & initial_metadata_flags_mask) ==
         initial_metadata_flags_eq) {
-      grpc_exec_ctx_sched(
+      grpc_closure_sched(
           exec_ctx, pp->on_complete,
-          GRPC_ERROR_CREATE_REFERENCING("Pick Cancelled", &error, 1), NULL);
+          GRPC_ERROR_CREATE_REFERENCING("Pick Cancelled", &error, 1));
       gpr_free(pp);
     } else {
       pp->next = p->pending_picks;
@@ -306,14 +306,15 @@ static void pf_connectivity_changed(grpc_exec_ctx *exec_ctx, void *arg,
         /* drop the pick list: we are connected now */
         GRPC_LB_POLICY_WEAK_REF(&p->base, "destroy_subchannels");
         gpr_atm_rel_store(&p->selected, (gpr_atm)selected);
-        grpc_exec_ctx_sched(exec_ctx,
-                            grpc_closure_create(destroy_subchannels, p),
-                            GRPC_ERROR_NONE, NULL);
+        grpc_closure_sched(exec_ctx,
+                           grpc_closure_create(destroy_subchannels, p,
+                                               grpc_schedule_on_exec_ctx),
+                           GRPC_ERROR_NONE);
         /* update any calls that were waiting for a pick */
         while ((pp = p->pending_picks)) {
           p->pending_picks = pp->next;
           *pp->target = GRPC_CONNECTED_SUBCHANNEL_REF(selected, "picked");
-          grpc_exec_ctx_sched(exec_ctx, pp->on_complete, GRPC_ERROR_NONE, NULL);
+          grpc_closure_sched(exec_ctx, pp->on_complete, GRPC_ERROR_NONE);
           gpr_free(pp);
         }
         grpc_connected_subchannel_notify_on_state_change(
@@ -366,8 +367,7 @@ static void pf_connectivity_changed(grpc_exec_ctx *exec_ctx, void *arg,
           while ((pp = p->pending_picks)) {
             p->pending_picks = pp->next;
             *pp->target = NULL;
-            grpc_exec_ctx_sched(exec_ctx, pp->on_complete, GRPC_ERROR_NONE,
-                                NULL);
+            grpc_closure_sched(exec_ctx, pp->on_complete, GRPC_ERROR_NONE);
             gpr_free(pp);
           }
           GRPC_LB_POLICY_WEAK_UNREF(exec_ctx, &p->base,
@@ -419,8 +419,7 @@ static void pf_ping_one(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
   if (selected) {
     grpc_connected_subchannel_ping(exec_ctx, selected, closure);
   } else {
-    grpc_exec_ctx_sched(exec_ctx, closure, GRPC_ERROR_CREATE("Not connected"),
-                        NULL);
+    grpc_closure_sched(exec_ctx, closure, GRPC_ERROR_CREATE("Not connected"));
   }
 }
 
@@ -485,7 +484,8 @@ static grpc_lb_policy *create_pick_first(grpc_exec_ctx *exec_ctx,
   p->num_subchannels = subchannel_idx;
 
   grpc_lb_policy_init(&p->base, &pick_first_lb_policy_vtable);
-  grpc_closure_init(&p->connectivity_changed, pf_connectivity_changed, p);
+  grpc_closure_init(&p->connectivity_changed, pf_connectivity_changed, p,
+                    grpc_schedule_on_exec_ctx);
   gpr_mu_init(&p->mu);
   return &p->base;
 }
diff --git a/src/core/ext/lb_policy/round_robin/round_robin.c b/src/core/ext/lb_policy/round_robin/round_robin.c
index f0305473d2..47f20a1904 100644
--- a/src/core/ext/lb_policy/round_robin/round_robin.c
+++ b/src/core/ext/lb_policy/round_robin/round_robin.c
@@ -321,8 +321,8 @@ static void rr_shutdown(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol) {
   while ((pp = p->pending_picks)) {
     p->pending_picks = pp->next;
     *pp->target = NULL;
-    grpc_exec_ctx_sched(exec_ctx, pp->on_complete,
-                        GRPC_ERROR_CREATE("Channel Shutdown"), NULL);
+    grpc_closure_sched(exec_ctx, pp->on_complete,
+                       GRPC_ERROR_CREATE("Channel Shutdown"));
     gpr_free(pp);
   }
   grpc_connectivity_state_set(
@@ -348,9 +348,9 @@ static void rr_cancel_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
     pending_pick *next = pp->next;
     if (pp->target == target) {
       *target = NULL;
-      grpc_exec_ctx_sched(
+      grpc_closure_sched(
           exec_ctx, pp->on_complete,
-          GRPC_ERROR_CREATE_REFERENCING("Pick cancelled", &error, 1), NULL);
+          GRPC_ERROR_CREATE_REFERENCING("Pick cancelled", &error, 1));
       gpr_free(pp);
     } else {
       pp->next = p->pending_picks;
@@ -376,9 +376,9 @@ static void rr_cancel_picks(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
     if ((pp->initial_metadata_flags & initial_metadata_flags_mask) ==
         initial_metadata_flags_eq) {
       *pp->target = NULL;
-      grpc_exec_ctx_sched(
+      grpc_closure_sched(
           exec_ctx, pp->on_complete,
-          GRPC_ERROR_CREATE_REFERENCING("Pick cancelled", &error, 1), NULL);
+          GRPC_ERROR_CREATE_REFERENCING("Pick cancelled", &error, 1));
       gpr_free(pp);
     } else {
       pp->next = p->pending_picks;
@@ -581,7 +581,7 @@ static void rr_connectivity_changed(grpc_exec_ctx *exec_ctx, void *arg,
                   "[RR CONN CHANGED] TARGET <-- SUBCHANNEL %p (NODE %p)",
                   (void *)selected->subchannel, (void *)selected);
         }
-        grpc_exec_ctx_sched(exec_ctx, pp->on_complete, GRPC_ERROR_NONE, NULL);
+        grpc_closure_sched(exec_ctx, pp->on_complete, GRPC_ERROR_NONE);
         gpr_free(pp);
       }
       update_lb_connectivity_status(exec_ctx, sd, error);
@@ -634,7 +634,7 @@ static void rr_connectivity_changed(grpc_exec_ctx *exec_ctx, void *arg,
         while ((pp = p->pending_picks)) {
           p->pending_picks = pp->next;
           *pp->target = NULL;
-          grpc_exec_ctx_sched(exec_ctx, pp->on_complete, GRPC_ERROR_NONE, NULL);
+          grpc_closure_sched(exec_ctx, pp->on_complete, GRPC_ERROR_NONE);
           gpr_free(pp);
         }
       }
@@ -684,8 +684,8 @@ static void rr_ping_one(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
     GRPC_CONNECTED_SUBCHANNEL_UNREF(exec_ctx, target, "rr_picked");
   } else {
     gpr_mu_unlock(&p->mu);
-    grpc_exec_ctx_sched(exec_ctx, closure,
-                        GRPC_ERROR_CREATE("Round Robin not connected"), NULL);
+    grpc_closure_sched(exec_ctx, closure,
+                       GRPC_ERROR_CREATE("Round Robin not connected"));
   }
 }
 
@@ -749,7 +749,7 @@ static grpc_lb_policy *round_robin_create(grpc_exec_ctx *exec_ctx,
       }
       ++subchannel_idx;
       grpc_closure_init(&sd->connectivity_changed_closure,
-                        rr_connectivity_changed, sd);
+                        rr_connectivity_changed, sd, grpc_schedule_on_exec_ctx);
     }
   }
   if (subchannel_idx == 0) {
diff --git a/src/core/ext/load_reporting/load_reporting_filter.c b/src/core/ext/load_reporting/load_reporting_filter.c
index 18bb826948..1403eb0d33 100644
--- a/src/core/ext/load_reporting/load_reporting_filter.c
+++ b/src/core/ext/load_reporting/load_reporting_filter.c
@@ -114,7 +114,8 @@ static grpc_error *init_call_elem(grpc_exec_ctx *exec_ctx,
   memset(calld, 0, sizeof(call_data));
 
   calld->id = (intptr_t)args->call_stack;
-  grpc_closure_init(&calld->on_initial_md_ready, on_initial_md_ready, elem);
+  grpc_closure_init(&calld->on_initial_md_ready, on_initial_md_ready, elem,
+                    grpc_schedule_on_exec_ctx);
 
   /* TODO(dgq): do something with the data
   channel_data *chand = elem->channel_data;
diff --git a/src/core/ext/resolver/dns/native/dns_resolver.c b/src/core/ext/resolver/dns/native/dns_resolver.c
index 2675fa931f..efbb2be4e1 100644
--- a/src/core/ext/resolver/dns/native/dns_resolver.c
+++ b/src/core/ext/resolver/dns/native/dns_resolver.c
@@ -112,8 +112,8 @@ static void dns_shutdown(grpc_exec_ctx *exec_ctx, grpc_resolver *resolver) {
   }
   if (r->next_completion != NULL) {
     *r->target_result = NULL;
-    grpc_exec_ctx_sched(exec_ctx, r->next_completion,
-                        GRPC_ERROR_CREATE("Resolver Shutdown"), NULL);
+    grpc_closure_sched(exec_ctx, r->next_completion,
+                       GRPC_ERROR_CREATE("Resolver Shutdown"));
     r->next_completion = NULL;
   }
   gpr_mu_unlock(&r->mu);
@@ -219,9 +219,10 @@ static void dns_start_resolving_locked(grpc_exec_ctx *exec_ctx,
   GPR_ASSERT(!r->resolving);
   r->resolving = true;
   r->addresses = NULL;
-  grpc_resolve_address(exec_ctx, r->name_to_resolve, r->default_port,
-                       r->interested_parties,
-                       grpc_closure_create(dns_on_resolved, r), &r->addresses);
+  grpc_resolve_address(
+      exec_ctx, r->name_to_resolve, r->default_port, r->interested_parties,
+      grpc_closure_create(dns_on_resolved, r, grpc_schedule_on_exec_ctx),
+      &r->addresses);
 }
 
 static void dns_maybe_finish_next_locked(grpc_exec_ctx *exec_ctx,
@@ -231,7 +232,7 @@ static void dns_maybe_finish_next_locked(grpc_exec_ctx *exec_ctx,
     *r->target_result = r->resolved_result == NULL
                             ? NULL
                             : grpc_channel_args_copy(r->resolved_result);
-    grpc_exec_ctx_sched(exec_ctx, r->next_completion, GRPC_ERROR_NONE, NULL);
+    grpc_closure_sched(exec_ctx, r->next_completion, GRPC_ERROR_NONE);
     r->next_completion = NULL;
     r->published_version = r->resolved_version;
   }
diff --git a/src/core/ext/resolver/sockaddr/sockaddr_resolver.c b/src/core/ext/resolver/sockaddr/sockaddr_resolver.c
index 88808c674f..55ea502c9e 100644
--- a/src/core/ext/resolver/sockaddr/sockaddr_resolver.c
+++ b/src/core/ext/resolver/sockaddr/sockaddr_resolver.c
@@ -89,7 +89,7 @@ static void sockaddr_shutdown(grpc_exec_ctx *exec_ctx,
   gpr_mu_lock(&r->mu);
   if (r->next_completion != NULL) {
     *r->target_result = NULL;
-    grpc_exec_ctx_sched(exec_ctx, r->next_completion, GRPC_ERROR_NONE, NULL);
+    grpc_closure_sched(exec_ctx, r->next_completion, GRPC_ERROR_NONE);
     r->next_completion = NULL;
   }
   gpr_mu_unlock(&r->mu);
@@ -123,7 +123,7 @@ static void sockaddr_maybe_finish_next_locked(grpc_exec_ctx *exec_ctx,
     grpc_arg arg = grpc_lb_addresses_create_channel_arg(r->addresses);
     *r->target_result =
         grpc_channel_args_copy_and_add(r->channel_args, &arg, 1);
-    grpc_exec_ctx_sched(exec_ctx, r->next_completion, GRPC_ERROR_NONE, NULL);
+    grpc_closure_sched(exec_ctx, r->next_completion, GRPC_ERROR_NONE);
     r->next_completion = NULL;
   }
 }
diff --git a/src/core/ext/transport/chttp2/client/chttp2_connector.c b/src/core/ext/transport/chttp2/client/chttp2_connector.c
index 114bb07222..be0d42605f 100644
--- a/src/core/ext/transport/chttp2/client/chttp2_connector.c
+++ b/src/core/ext/transport/chttp2/client/chttp2_connector.c
@@ -47,7 +47,6 @@
 #include "src/core/lib/channel/channel_args.h"
 #include "src/core/lib/channel/handshaker.h"
 #include "src/core/lib/iomgr/tcp_client.h"
-#include "src/core/lib/security/transport/security_connector.h"
 
 typedef struct {
   grpc_connector base;
@@ -141,7 +140,7 @@ static void on_handshake_done(grpc_exec_ctx *exec_ctx, void *arg,
   }
   grpc_closure *notify = c->notify;
   c->notify = NULL;
-  grpc_exec_ctx_sched(exec_ctx, notify, error, NULL);
+  grpc_closure_sched(exec_ctx, notify, error);
   grpc_handshake_manager_destroy(exec_ctx, c->handshake_mgr);
   c->handshake_mgr = NULL;
   gpr_mu_unlock(&c->mu);
@@ -180,7 +179,7 @@ static void on_initial_connect_string_sent(grpc_exec_ctx *exec_ctx, void *arg,
     memset(c->result, 0, sizeof(*c->result));
     grpc_closure *notify = c->notify;
     c->notify = NULL;
-    grpc_exec_ctx_sched(exec_ctx, notify, error, NULL);
+    grpc_closure_sched(exec_ctx, notify, error);
     gpr_mu_unlock(&c->mu);
     chttp2_connector_unref(exec_ctx, arg);
   } else {
@@ -203,7 +202,7 @@ static void connected(grpc_exec_ctx *exec_ctx, void *arg, grpc_error *error) {
     memset(c->result, 0, sizeof(*c->result));
     grpc_closure *notify = c->notify;
     c->notify = NULL;
-    grpc_exec_ctx_sched(exec_ctx, notify, error, NULL);
+    grpc_closure_sched(exec_ctx, notify, error);
     if (c->endpoint != NULL) grpc_endpoint_shutdown(exec_ctx, c->endpoint);
     gpr_mu_unlock(&c->mu);
     chttp2_connector_unref(exec_ctx, arg);
@@ -211,7 +210,7 @@ static void connected(grpc_exec_ctx *exec_ctx, void *arg, grpc_error *error) {
     GPR_ASSERT(c->endpoint != NULL);
     if (!GRPC_SLICE_IS_EMPTY(c->args.initial_connect_string)) {
       grpc_closure_init(&c->initial_string_sent, on_initial_connect_string_sent,
-                        c);
+                        c, grpc_schedule_on_exec_ctx);
       grpc_slice_buffer_init(&c->initial_string_buffer);
       grpc_slice_buffer_add(&c->initial_string_buffer,
                             c->args.initial_connect_string);
@@ -237,7 +236,7 @@ static void chttp2_connector_connect(grpc_exec_ctx *exec_ctx,
   c->result = result;
   GPR_ASSERT(c->endpoint == NULL);
   chttp2_connector_ref(con);  // Ref taken for callback.
-  grpc_closure_init(&c->connected, connected, c);
+  grpc_closure_init(&c->connected, connected, c, grpc_schedule_on_exec_ctx);
   GPR_ASSERT(!c->connecting);
   c->connecting = true;
   grpc_tcp_client_connect(exec_ctx, &c->connected, &c->endpoint,
diff --git a/src/core/ext/transport/chttp2/server/chttp2_server.c b/src/core/ext/transport/chttp2/server/chttp2_server.c
index f0857714fc..9af62d372e 100644
--- a/src/core/ext/transport/chttp2/server/chttp2_server.c
+++ b/src/core/ext/transport/chttp2/server/chttp2_server.c
@@ -281,7 +281,8 @@ grpc_error *grpc_chttp2_server_add_port(
   state = gpr_malloc(sizeof(*state));
   memset(state, 0, sizeof(*state));
   grpc_closure_init(&state->tcp_server_shutdown_complete,
-                    tcp_server_shutdown_complete, state);
+                    tcp_server_shutdown_complete, state,
+                    grpc_schedule_on_exec_ctx);
   err = grpc_tcp_server_create(exec_ctx, &state->tcp_server_shutdown_complete,
                                args, &tcp_server);
   if (err != GRPC_ERROR_NONE) {
diff --git a/src/core/ext/transport/chttp2/transport/chttp2_transport.c b/src/core/ext/transport/chttp2/transport/chttp2_transport.c
index 6bc054866b..488c3b93cc 100644
--- a/src/core/ext/transport/chttp2/transport/chttp2_transport.c
+++ b/src/core/ext/transport/chttp2/transport/chttp2_transport.c
@@ -73,20 +73,14 @@ static const grpc_transport_vtable vtable;
 static void write_action_begin_locked(grpc_exec_ctx *exec_ctx, void *t,
                                       grpc_error *error);
 static void write_action(grpc_exec_ctx *exec_ctx, void *t, grpc_error *error);
-static void write_action_end(grpc_exec_ctx *exec_ctx, void *t,
-                             grpc_error *error);
 static void write_action_end_locked(grpc_exec_ctx *exec_ctx, void *t,
                                     grpc_error *error);
 
-static void read_action_begin(grpc_exec_ctx *exec_ctx, void *t,
-                              grpc_error *error);
 static void read_action_locked(grpc_exec_ctx *exec_ctx, void *t,
                                grpc_error *error);
 
 static void complete_fetch_locked(grpc_exec_ctx *exec_ctx, void *gs,
                                   grpc_error *error);
-static void complete_fetch(grpc_exec_ctx *exec_ctx, void *gs,
-                           grpc_error *error);
 /** Set a transport level setting, and push it to our peer */
 static void push_setting(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
                          grpc_chttp2_setting_id id, uint32_t value);
@@ -112,12 +106,8 @@ static void incoming_byte_stream_destroy_locked(grpc_exec_ctx *exec_ctx,
                                                 void *byte_stream,
                                                 grpc_error *error_ignored);
 
-static void benign_reclaimer(grpc_exec_ctx *exec_ctx, void *t,
-                             grpc_error *error);
 static void benign_reclaimer_locked(grpc_exec_ctx *exec_ctx, void *t,
                                     grpc_error *error);
-static void destructive_reclaimer(grpc_exec_ctx *exec_ctx, void *t,
-                                  grpc_error *error);
 static void destructive_reclaimer_locked(grpc_exec_ctx *exec_ctx, void *t,
                                          grpc_error *error);
 
@@ -166,8 +156,8 @@ static void destruct_transport(grpc_exec_ctx *exec_ctx,
      and maybe they hold resources that need to be freed */
   while (t->pings.next != &t->pings) {
     grpc_chttp2_outstanding_ping *ping = t->pings.next;
-    grpc_exec_ctx_sched(exec_ctx, ping->on_recv,
-                        GRPC_ERROR_CREATE("Transport closed"), NULL);
+    grpc_closure_sched(exec_ctx, ping->on_recv,
+                       GRPC_ERROR_CREATE("Transport closed"));
     ping->next->prev = ping->prev;
     ping->prev->next = ping->next;
     gpr_free(ping);
@@ -246,18 +236,15 @@ static void init_transport(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
   grpc_slice_buffer_init(&t->outbuf);
   grpc_chttp2_hpack_compressor_init(&t->hpack_compressor);
 
-  grpc_closure_init(&t->write_action_begin_locked, write_action_begin_locked,
-                    t);
-  grpc_closure_init(&t->write_action, write_action, t);
-  grpc_closure_init(&t->write_action_end, write_action_end, t);
-  grpc_closure_init(&t->write_action_end_locked, write_action_end_locked, t);
-  grpc_closure_init(&t->read_action_begin, read_action_begin, t);
-  grpc_closure_init(&t->read_action_locked, read_action_locked, t);
-  grpc_closure_init(&t->benign_reclaimer, benign_reclaimer, t);
-  grpc_closure_init(&t->destructive_reclaimer, destructive_reclaimer, t);
-  grpc_closure_init(&t->benign_reclaimer_locked, benign_reclaimer_locked, t);
+  grpc_closure_init(&t->write_action, write_action, t,
+                    grpc_schedule_on_exec_ctx);
+  grpc_closure_init(&t->read_action_locked, read_action_locked, t,
+                    grpc_combiner_scheduler(t->combiner, false));
+  grpc_closure_init(&t->benign_reclaimer_locked, benign_reclaimer_locked, t,
+                    grpc_combiner_scheduler(t->combiner, false));
   grpc_closure_init(&t->destructive_reclaimer_locked,
-                    destructive_reclaimer_locked, t);
+                    destructive_reclaimer_locked, t,
+                    grpc_combiner_scheduler(t->combiner, false));
 
   grpc_chttp2_goaway_parser_init(&t->goaway_parser);
   grpc_chttp2_hpack_parser_init(&t->hpack_parser);
@@ -395,9 +382,10 @@ static void destroy_transport_locked(grpc_exec_ctx *exec_ctx, void *tp,
 
 static void destroy_transport(grpc_exec_ctx *exec_ctx, grpc_transport *gt) {
   grpc_chttp2_transport *t = (grpc_chttp2_transport *)gt;
-  grpc_combiner_execute(exec_ctx, t->combiner,
-                        grpc_closure_create(destroy_transport_locked, t),
-                        GRPC_ERROR_NONE, false);
+  grpc_closure_sched(exec_ctx, grpc_closure_create(
+                                   destroy_transport_locked, t,
+                                   grpc_combiner_scheduler(t->combiner, false)),
+                     GRPC_ERROR_NONE);
 }
 
 static void close_transport_locked(grpc_exec_ctx *exec_ctx,
@@ -471,8 +459,8 @@ static int init_stream(grpc_exec_ctx *exec_ctx, grpc_transport *gt,
   grpc_chttp2_data_parser_init(&s->data_parser);
   grpc_slice_buffer_init(&s->flow_controlled_buffer);
   s->deadline = gpr_inf_future(GPR_CLOCK_MONOTONIC);
-  grpc_closure_init(&s->complete_fetch, complete_fetch, s);
-  grpc_closure_init(&s->complete_fetch_locked, complete_fetch_locked, s);
+  grpc_closure_init(&s->complete_fetch_locked, complete_fetch_locked, s,
+                    grpc_schedule_on_exec_ctx);
 
   GRPC_CHTTP2_REF_TRANSPORT(t, "stream");
 
@@ -547,9 +535,10 @@ static void destroy_stream(grpc_exec_ctx *exec_ctx, grpc_transport *gt,
   grpc_chttp2_stream *s = (grpc_chttp2_stream *)gs;
 
   s->destroy_stream_arg = and_free_memory;
-  grpc_closure_init(&s->destroy_stream, destroy_stream_locked, s);
-  grpc_combiner_execute(exec_ctx, t->combiner, &s->destroy_stream,
-                        GRPC_ERROR_NONE, false);
+  grpc_closure_sched(
+      exec_ctx, grpc_closure_init(&s->destroy_stream, destroy_stream_locked, s,
+                                  grpc_combiner_scheduler(t->combiner, false)),
+      GRPC_ERROR_NONE);
   GPR_TIMER_END("destroy_stream", 0);
 }
 
@@ -600,7 +589,7 @@ static void set_write_state(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
                                  write_state_name(st), reason));
   t->write_state = st;
   if (st == GRPC_CHTTP2_WRITE_STATE_IDLE) {
-    grpc_exec_ctx_enqueue_list(exec_ctx, &t->run_after_write, NULL);
+    grpc_closure_list_sched(exec_ctx, &t->run_after_write);
     if (t->close_transport_on_writes_finished != NULL) {
       grpc_error *err = t->close_transport_on_writes_finished;
       t->close_transport_on_writes_finished = NULL;
@@ -618,9 +607,12 @@ void grpc_chttp2_initiate_write(grpc_exec_ctx *exec_ctx,
     case GRPC_CHTTP2_WRITE_STATE_IDLE:
       set_write_state(exec_ctx, t, GRPC_CHTTP2_WRITE_STATE_WRITING, reason);
       GRPC_CHTTP2_REF_TRANSPORT(t, "writing");
-      grpc_combiner_execute_finally(exec_ctx, t->combiner,
-                                    &t->write_action_begin_locked,
-                                    GRPC_ERROR_NONE, covered_by_poller);
+      grpc_closure_sched(
+          exec_ctx,
+          grpc_closure_init(
+              &t->write_action_begin_locked, write_action_begin_locked, t,
+              grpc_combiner_finally_scheduler(t->combiner, covered_by_poller)),
+          GRPC_ERROR_NONE);
       break;
     case GRPC_CHTTP2_WRITE_STATE_WRITING:
       set_write_state(
@@ -662,7 +654,7 @@ static void write_action_begin_locked(grpc_exec_ctx *exec_ctx, void *gt,
   if (!t->closed && grpc_chttp2_begin_write(exec_ctx, t)) {
     set_write_state(exec_ctx, t, GRPC_CHTTP2_WRITE_STATE_WRITING,
                     "begin writing");
-    grpc_exec_ctx_sched(exec_ctx, &t->write_action, GRPC_ERROR_NONE, NULL);
+    grpc_closure_sched(exec_ctx, &t->write_action, GRPC_ERROR_NONE);
   } else {
     set_write_state(exec_ctx, t, GRPC_CHTTP2_WRITE_STATE_IDLE,
                     "begin writing nothing");
@@ -674,19 +666,13 @@ static void write_action_begin_locked(grpc_exec_ctx *exec_ctx, void *gt,
 static void write_action(grpc_exec_ctx *exec_ctx, void *gt, grpc_error *error) {
   grpc_chttp2_transport *t = gt;
   GPR_TIMER_BEGIN("write_action", 0);
-  grpc_endpoint_write(exec_ctx, t->ep, &t->outbuf, &t->write_action_end);
+  grpc_endpoint_write(
+      exec_ctx, t->ep, &t->outbuf,
+      grpc_closure_init(&t->write_action_end_locked, write_action_end_locked, t,
+                        grpc_combiner_scheduler(t->combiner, false)));
   GPR_TIMER_END("write_action", 0);
 }
 
-static void write_action_end(grpc_exec_ctx *exec_ctx, void *gt,
-                             grpc_error *error) {
-  grpc_chttp2_transport *t = gt;
-  GPR_TIMER_BEGIN("write_action_end", 0);
-  grpc_combiner_execute(exec_ctx, t->combiner, &t->write_action_end_locked,
-                        GRPC_ERROR_REF(error), false);
-  GPR_TIMER_END("write_action_end", 0);
-}
-
 static void write_action_end_locked(grpc_exec_ctx *exec_ctx, void *tp,
                                     grpc_error *error) {
   GPR_TIMER_BEGIN("terminate_writing_with_lock", 0);
@@ -716,18 +702,24 @@ static void write_action_end_locked(grpc_exec_ctx *exec_ctx, void *tp,
       set_write_state(exec_ctx, t, GRPC_CHTTP2_WRITE_STATE_WRITING,
                       "continue writing [!covered]");
       GRPC_CHTTP2_REF_TRANSPORT(t, "writing");
-      grpc_combiner_execute_finally(exec_ctx, t->combiner,
-                                    &t->write_action_begin_locked,
-                                    GRPC_ERROR_NONE, false);
+      grpc_closure_run(
+          exec_ctx,
+          grpc_closure_init(
+              &t->write_action_begin_locked, write_action_begin_locked, t,
+              grpc_combiner_finally_scheduler(t->combiner, false)),
+          GRPC_ERROR_NONE);
       break;
     case GRPC_CHTTP2_WRITE_STATE_WRITING_WITH_MORE_AND_COVERED_BY_POLLER:
       GPR_TIMER_MARK("state=writing_stale_with_poller", 0);
       set_write_state(exec_ctx, t, GRPC_CHTTP2_WRITE_STATE_WRITING,
                       "continue writing [covered]");
       GRPC_CHTTP2_REF_TRANSPORT(t, "writing");
-      grpc_combiner_execute_finally(exec_ctx, t->combiner,
-                                    &t->write_action_begin_locked,
-                                    GRPC_ERROR_NONE, true);
+      grpc_closure_run(
+          exec_ctx,
+          grpc_closure_init(&t->write_action_begin_locked,
+                            write_action_begin_locked, t,
+                            grpc_combiner_finally_scheduler(t->combiner, true)),
+          GRPC_ERROR_NONE);
       break;
   }
 
@@ -965,15 +957,6 @@ static void complete_fetch_locked(grpc_exec_ctx *exec_ctx, void *gs,
   }
 }
 
-static void complete_fetch(grpc_exec_ctx *exec_ctx, void *gs,
-                           grpc_error *error) {
-  grpc_chttp2_stream *s = gs;
-  grpc_chttp2_transport *t = s->t;
-  grpc_combiner_execute(exec_ctx, t->combiner, &s->complete_fetch_locked,
-                        GRPC_ERROR_REF(error),
-                        s->complete_fetch_covered_by_poller);
-}
-
 static void do_nothing(grpc_exec_ctx *exec_ctx, void *arg, grpc_error *error) {}
 
 static void log_metadata(const grpc_metadata_batch *md_batch, uint32_t id,
@@ -1009,7 +992,8 @@ static void perform_stream_op_locked(grpc_exec_ctx *exec_ctx, void *stream_op,
 
   grpc_closure *on_complete = op->on_complete;
   if (on_complete == NULL) {
-    on_complete = grpc_closure_create(do_nothing, NULL);
+    on_complete =
+        grpc_closure_create(do_nothing, NULL, grpc_schedule_on_exec_ctx);
   }
 
   /* use final_data as a barrier until enqueue time; the inital counter is
@@ -1212,13 +1196,15 @@ static void perform_stream_op(grpc_exec_ctx *exec_ctx, grpc_transport *gt,
     gpr_free(str);
   }
 
-  grpc_closure_init(&op->transport_private.closure, perform_stream_op_locked,
-                    op);
   op->transport_private.args[0] = gt;
   op->transport_private.args[1] = gs;
   GRPC_CHTTP2_STREAM_REF(s, "perform_stream_op");
-  grpc_combiner_execute(exec_ctx, t->combiner, &op->transport_private.closure,
-                        GRPC_ERROR_NONE, op->covered_by_poller);
+  grpc_closure_sched(
+      exec_ctx,
+      grpc_closure_init(
+          &op->transport_private.closure, perform_stream_op_locked, op,
+          grpc_combiner_scheduler(t->combiner, op->covered_by_poller)),
+      GRPC_ERROR_NONE);
   GPR_TIMER_END("perform_stream_op", 0);
 }
 
@@ -1247,7 +1233,7 @@ void grpc_chttp2_ack_ping(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
   grpc_chttp2_outstanding_ping *ping;
   for (ping = t->pings.next; ping != &t->pings; ping = ping->next) {
     if (0 == memcmp(opaque_8bytes, ping->id, 8)) {
-      grpc_exec_ctx_sched(exec_ctx, ping->on_recv, GRPC_ERROR_NONE, NULL);
+      grpc_closure_sched(exec_ctx, ping->on_recv, GRPC_ERROR_NONE);
       ping->next->prev = ping->prev;
       ping->prev->next = ping->next;
       gpr_free(ping);
@@ -1321,11 +1307,12 @@ static void perform_transport_op(grpc_exec_ctx *exec_ctx, grpc_transport *gt,
   char *msg = grpc_transport_op_string(op);
   gpr_free(msg);
   op->transport_private.args[0] = gt;
-  grpc_closure_init(&op->transport_private.closure, perform_transport_op_locked,
-                    op);
   GRPC_CHTTP2_REF_TRANSPORT(t, "transport_op");
-  grpc_combiner_execute(exec_ctx, t->combiner, &op->transport_private.closure,
-                        GRPC_ERROR_NONE, false);
+  grpc_closure_sched(
+      exec_ctx, grpc_closure_init(&op->transport_private.closure,
+                                  perform_transport_op_locked, op,
+                                  grpc_combiner_scheduler(t->combiner, false)),
+      GRPC_ERROR_NONE);
 }
 
 /*******************************************************************************
@@ -1801,19 +1788,6 @@ static void update_global_window(void *args, uint32_t id, void *stream) {
  * INPUT PROCESSING - PARSING
  */
 
-static void read_action_begin(grpc_exec_ctx *exec_ctx, void *tp,
-                              grpc_error *error) {
-  /* Control flow:
-     reading_action_locked ->
-       (parse_unlocked -> post_parse_locked)? ->
-       post_reading_action_locked */
-  GPR_TIMER_BEGIN("reading_action", 0);
-  grpc_chttp2_transport *t = tp;
-  grpc_combiner_execute(exec_ctx, t->combiner, &t->read_action_locked,
-                        GRPC_ERROR_REF(error), false);
-  GPR_TIMER_END("reading_action", 0);
-}
-
 static grpc_error *try_http_parsing(grpc_exec_ctx *exec_ctx,
                                     grpc_chttp2_transport *t) {
   grpc_http_parser parser;
@@ -1913,7 +1887,8 @@ static void read_action_locked(grpc_exec_ctx *exec_ctx, void *tp,
   grpc_slice_buffer_reset_and_unref(&t->read_buffer);
 
   if (keep_reading) {
-    grpc_endpoint_read(exec_ctx, t->ep, &t->read_buffer, &t->read_action_begin);
+    grpc_endpoint_read(exec_ctx, t->ep, &t->read_buffer,
+                       &t->read_action_locked);
     GRPC_CHTTP2_UNREF_TRANSPORT(exec_ctx, t, "keep_reading");
   } else {
     GRPC_CHTTP2_UNREF_TRANSPORT(exec_ctx, t, "reading_action");
@@ -2050,10 +2025,12 @@ static int incoming_byte_stream_next(grpc_exec_ctx *exec_ctx,
   bs->next_action.slice = slice;
   bs->next_action.max_size_hint = max_size_hint;
   bs->next_action.on_complete = on_complete;
-  grpc_closure_init(&bs->next_action.closure, incoming_byte_stream_next_locked,
-                    bs);
-  grpc_combiner_execute(exec_ctx, bs->transport->combiner,
-                        &bs->next_action.closure, GRPC_ERROR_NONE, false);
+  grpc_closure_sched(
+      exec_ctx,
+      grpc_closure_init(
+          &bs->next_action.closure, incoming_byte_stream_next_locked, bs,
+          grpc_combiner_scheduler(bs->transport->combiner, false)),
+      GRPC_ERROR_NONE);
   GPR_TIMER_END("incoming_byte_stream_next", 0);
   return 0;
 }
@@ -2075,10 +2052,12 @@ static void incoming_byte_stream_destroy(grpc_exec_ctx *exec_ctx,
   GPR_TIMER_BEGIN("incoming_byte_stream_destroy", 0);
   grpc_chttp2_incoming_byte_stream *bs =
       (grpc_chttp2_incoming_byte_stream *)byte_stream;
-  grpc_closure_init(&bs->destroy_action, incoming_byte_stream_destroy_locked,
-                    bs);
-  grpc_combiner_execute(exec_ctx, bs->transport->combiner, &bs->destroy_action,
-                        GRPC_ERROR_NONE, false);
+  grpc_closure_sched(
+      exec_ctx,
+      grpc_closure_init(
+          &bs->destroy_action, incoming_byte_stream_destroy_locked, bs,
+          grpc_combiner_scheduler(bs->transport->combiner, false)),
+      GRPC_ERROR_NONE);
   GPR_TIMER_END("incoming_byte_stream_destroy", 0);
 }
 
@@ -2086,7 +2065,7 @@ static void incoming_byte_stream_publish_error(
     grpc_exec_ctx *exec_ctx, grpc_chttp2_incoming_byte_stream *bs,
     grpc_error *error) {
   GPR_ASSERT(error != GRPC_ERROR_NONE);
-  grpc_exec_ctx_sched(exec_ctx, bs->on_next, GRPC_ERROR_REF(error), NULL);
+  grpc_closure_sched(exec_ctx, bs->on_next, GRPC_ERROR_REF(error));
   bs->on_next = NULL;
   GRPC_ERROR_UNREF(bs->error);
   bs->error = error;
@@ -2103,7 +2082,7 @@ void grpc_chttp2_incoming_byte_stream_push(grpc_exec_ctx *exec_ctx,
     bs->remaining_bytes -= (uint32_t)GRPC_SLICE_LENGTH(slice);
     if (bs->on_next != NULL) {
       *bs->next = slice;
-      grpc_exec_ctx_sched(exec_ctx, bs->on_next, GRPC_ERROR_NONE, NULL);
+      grpc_closure_sched(exec_ctx, bs->on_next, GRPC_ERROR_NONE);
       bs->on_next = NULL;
     } else {
       grpc_slice_buffer_add(&bs->slices, slice);
@@ -2171,7 +2150,7 @@ static void post_benign_reclaimer(grpc_exec_ctx *exec_ctx,
     GRPC_CHTTP2_REF_TRANSPORT(t, "benign_reclaimer");
     grpc_resource_user_post_reclaimer(exec_ctx,
                                       grpc_endpoint_get_resource_user(t->ep),
-                                      false, &t->benign_reclaimer);
+                                      false, &t->benign_reclaimer_locked);
   }
 }
 
@@ -2182,24 +2161,10 @@ static void post_destructive_reclaimer(grpc_exec_ctx *exec_ctx,
     GRPC_CHTTP2_REF_TRANSPORT(t, "destructive_reclaimer");
     grpc_resource_user_post_reclaimer(exec_ctx,
                                       grpc_endpoint_get_resource_user(t->ep),
-                                      true, &t->destructive_reclaimer);
+                                      true, &t->destructive_reclaimer_locked);
   }
 }
 
-static void benign_reclaimer(grpc_exec_ctx *exec_ctx, void *arg,
-                             grpc_error *error) {
-  grpc_chttp2_transport *t = arg;
-  grpc_combiner_execute(exec_ctx, t->combiner, &t->benign_reclaimer_locked,
-                        GRPC_ERROR_REF(error), false);
-}
-
-static void destructive_reclaimer(grpc_exec_ctx *exec_ctx, void *arg,
-                                  grpc_error *error) {
-  grpc_chttp2_transport *t = arg;
-  grpc_combiner_execute(exec_ctx, t->combiner, &t->destructive_reclaimer_locked,
-                        GRPC_ERROR_REF(error), false);
-}
-
 static void benign_reclaimer_locked(grpc_exec_ctx *exec_ctx, void *arg,
                                     grpc_error *error) {
   grpc_chttp2_transport *t = arg;
@@ -2380,5 +2345,5 @@ void grpc_chttp2_transport_start_reading(grpc_exec_ctx *exec_ctx,
     grpc_slice_buffer_move_into(read_buffer, &t->read_buffer);
     gpr_free(read_buffer);
   }
-  read_action_begin(exec_ctx, t, GRPC_ERROR_NONE);
+  grpc_closure_sched(exec_ctx, &t->read_action_locked, GRPC_ERROR_NONE);
 }
diff --git a/src/core/ext/transport/chttp2/transport/hpack_parser.c b/src/core/ext/transport/chttp2/transport/hpack_parser.c
index 6a9200b8db..64ce07b2f7 100644
--- a/src/core/ext/transport/chttp2/transport/hpack_parser.c
+++ b/src/core/ext/transport/chttp2/transport/hpack_parser.c
@@ -1634,10 +1634,11 @@ grpc_error *grpc_chttp2_header_parser_parse(grpc_exec_ctx *exec_ctx,
              however -- it might be that we receive a RST_STREAM following this
              and can avoid the extra write */
           GRPC_CHTTP2_STREAM_REF(s, "final_rst");
-          grpc_combiner_execute_finally(
-              exec_ctx, t->combiner,
-              grpc_closure_create(force_client_rst_stream, s), GRPC_ERROR_NONE,
-              false);
+          grpc_closure_sched(
+              exec_ctx, grpc_closure_create(force_client_rst_stream, s,
+                                            grpc_combiner_finally_scheduler(
+                                                t->combiner, false)),
+              GRPC_ERROR_NONE);
         }
         grpc_chttp2_mark_stream_closed(exec_ctx, t, s, true, false,
                                        GRPC_ERROR_NONE);
diff --git a/src/core/ext/transport/chttp2/transport/internal.h b/src/core/ext/transport/chttp2/transport/internal.h
index b727965d43..a52acbacdb 100644
--- a/src/core/ext/transport/chttp2/transport/internal.h
+++ b/src/core/ext/transport/chttp2/transport/internal.h
@@ -212,10 +212,8 @@ struct grpc_chttp2_transport {
 
   grpc_closure write_action_begin_locked;
   grpc_closure write_action;
-  grpc_closure write_action_end;
   grpc_closure write_action_end_locked;
 
-  grpc_closure read_action_begin;
   grpc_closure read_action_locked;
 
   /** incoming read bytes */
@@ -336,10 +334,8 @@ struct grpc_chttp2_transport {
   /** have we scheduled a destructive cleanup? */
   bool destructive_reclaimer_registered;
   /** benign cleanup closure */
-  grpc_closure benign_reclaimer;
   grpc_closure benign_reclaimer_locked;
   /** destructive cleanup closure */
-  grpc_closure destructive_reclaimer;
   grpc_closure destructive_reclaimer_locked;
 };
 
diff --git a/src/core/ext/transport/cronet/transport/cronet_transport.c b/src/core/ext/transport/cronet/transport/cronet_transport.c
index 4063dcaefc..48370654ca 100644
--- a/src/core/ext/transport/cronet/transport/cronet_transport.c
+++ b/src/core/ext/transport/cronet/transport/cronet_transport.c
@@ -955,17 +955,17 @@ static enum e_op_result execute_stream_op(grpc_exec_ctx *exec_ctx,
                            OP_RECV_INITIAL_METADATA)) {
     CRONET_LOG(GPR_DEBUG, "running: %p  OP_RECV_INITIAL_METADATA", oas);
     if (stream_state->state_op_done[OP_CANCEL_ERROR]) {
-      grpc_exec_ctx_sched(exec_ctx, stream_op->recv_initial_metadata_ready,
-                          GRPC_ERROR_CANCELLED, NULL);
+      grpc_closure_sched(exec_ctx, stream_op->recv_initial_metadata_ready,
+                         GRPC_ERROR_CANCELLED);
     } else if (stream_state->state_callback_received[OP_FAILED]) {
-      grpc_exec_ctx_sched(
+      grpc_closure_sched(
           exec_ctx, stream_op->recv_initial_metadata_ready,
-          make_error_with_desc(GRPC_STATUS_UNAVAILABLE, "Unavailable."), NULL);
+          make_error_with_desc(GRPC_STATUS_UNAVAILABLE, "Unavailable."));
     } else {
       grpc_chttp2_incoming_metadata_buffer_publish(
           &oas->s->state.rs.initial_metadata, stream_op->recv_initial_metadata);
-      grpc_exec_ctx_sched(exec_ctx, stream_op->recv_initial_metadata_ready,
-                          GRPC_ERROR_NONE, NULL);
+      grpc_closure_sched(exec_ctx, stream_op->recv_initial_metadata_ready,
+                         GRPC_ERROR_NONE);
     }
     stream_state->state_op_done[OP_RECV_INITIAL_METADATA] = true;
     result = ACTION_TAKEN_NO_CALLBACK;
@@ -975,22 +975,22 @@ static enum e_op_result execute_stream_op(grpc_exec_ctx *exec_ctx,
     CRONET_LOG(GPR_DEBUG, "running: %p  OP_RECV_MESSAGE", oas);
     if (stream_state->state_op_done[OP_CANCEL_ERROR]) {
       CRONET_LOG(GPR_DEBUG, "Stream is cancelled.");
-      grpc_exec_ctx_sched(exec_ctx, stream_op->recv_message_ready,
-                          GRPC_ERROR_CANCELLED, NULL);
+      grpc_closure_sched(exec_ctx, stream_op->recv_message_ready,
+                         GRPC_ERROR_CANCELLED);
       stream_state->state_op_done[OP_RECV_MESSAGE] = true;
       result = ACTION_TAKEN_NO_CALLBACK;
     } else if (stream_state->state_callback_received[OP_FAILED]) {
       CRONET_LOG(GPR_DEBUG, "Stream failed.");
-      grpc_exec_ctx_sched(
+      grpc_closure_sched(
           exec_ctx, stream_op->recv_message_ready,
-          make_error_with_desc(GRPC_STATUS_UNAVAILABLE, "Unavailable."), NULL);
+          make_error_with_desc(GRPC_STATUS_UNAVAILABLE, "Unavailable."));
       stream_state->state_op_done[OP_RECV_MESSAGE] = true;
       result = ACTION_TAKEN_NO_CALLBACK;
     } else if (stream_state->rs.read_stream_closed == true) {
       /* No more data will be received */
       CRONET_LOG(GPR_DEBUG, "read stream closed");
-      grpc_exec_ctx_sched(exec_ctx, stream_op->recv_message_ready,
-                          GRPC_ERROR_NONE, NULL);
+      grpc_closure_sched(exec_ctx, stream_op->recv_message_ready,
+                         GRPC_ERROR_NONE);
       stream_state->state_op_done[OP_RECV_MESSAGE] = true;
       oas->state.state_op_done[OP_RECV_MESSAGE] = true;
       result = ACTION_TAKEN_NO_CALLBACK;
@@ -1023,8 +1023,8 @@ static enum e_op_result execute_stream_op(grpc_exec_ctx *exec_ctx,
                                         &stream_state->rs.read_slice_buffer, 0);
           *((grpc_byte_buffer **)stream_op->recv_message) =
               (grpc_byte_buffer *)&stream_state->rs.sbs;
-          grpc_exec_ctx_sched(exec_ctx, stream_op->recv_message_ready,
-                              GRPC_ERROR_NONE, NULL);
+          grpc_closure_sched(exec_ctx, stream_op->recv_message_ready,
+                             GRPC_ERROR_NONE);
           stream_state->state_op_done[OP_RECV_MESSAGE] = true;
           oas->state.state_op_done[OP_RECV_MESSAGE] = true;
 
@@ -1068,8 +1068,8 @@ static enum e_op_result execute_stream_op(grpc_exec_ctx *exec_ctx,
                                     &stream_state->rs.read_slice_buffer, 0);
       *((grpc_byte_buffer **)stream_op->recv_message) =
           (grpc_byte_buffer *)&stream_state->rs.sbs;
-      grpc_exec_ctx_sched(exec_ctx, stream_op->recv_message_ready,
-                          GRPC_ERROR_NONE, NULL);
+      grpc_closure_sched(exec_ctx, stream_op->recv_message_ready,
+                         GRPC_ERROR_NONE);
       stream_state->state_op_done[OP_RECV_MESSAGE] = true;
       oas->state.state_op_done[OP_RECV_MESSAGE] = true;
       /* Do an extra read to trigger on_succeeded() callback in case connection
@@ -1115,18 +1115,17 @@ static enum e_op_result execute_stream_op(grpc_exec_ctx *exec_ctx,
                            OP_ON_COMPLETE)) {
     CRONET_LOG(GPR_DEBUG, "running: %p  OP_ON_COMPLETE", oas);
     if (stream_state->state_op_done[OP_CANCEL_ERROR]) {
-      grpc_exec_ctx_sched(exec_ctx, stream_op->on_complete,
-                          GRPC_ERROR_REF(stream_state->cancel_error), NULL);
+      grpc_closure_sched(exec_ctx, stream_op->on_complete,
+                         GRPC_ERROR_REF(stream_state->cancel_error));
     } else if (stream_state->state_callback_received[OP_FAILED]) {
-      grpc_exec_ctx_sched(
+      grpc_closure_sched(
           exec_ctx, stream_op->on_complete,
-          make_error_with_desc(GRPC_STATUS_UNAVAILABLE, "Unavailable."), NULL);
+          make_error_with_desc(GRPC_STATUS_UNAVAILABLE, "Unavailable."));
     } else {
       /* All actions in this stream_op are complete. Call the on_complete
        * callback
        */
-      grpc_exec_ctx_sched(exec_ctx, stream_op->on_complete, GRPC_ERROR_NONE,
-                          NULL);
+      grpc_closure_sched(exec_ctx, stream_op->on_complete, GRPC_ERROR_NONE);
     }
     oas->state.state_op_done[OP_ON_COMPLETE] = true;
     oas->done = true;