Merge branch 'master' into exp-cq-fix

15 files changed, 500 insertions, 220 deletions

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 d3a51c6e6f..a776a07d99 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
@@ -123,7 +123,6 @@
 #define GRPC_GRPCLB_RECONNECT_BACKOFF_MULTIPLIER 1.6
 #define GRPC_GRPCLB_RECONNECT_MAX_BACKOFF_SECONDS 120
 #define GRPC_GRPCLB_RECONNECT_JITTER 0.2
-#define GRPC_GRPCLB_DEFAULT_FALLBACK_TIMEOUT_MS 10000
 
 grpc_tracer_flag grpc_lb_glb_trace = GRPC_TRACER_INITIALIZER(false, "glb");
 
@@ -300,10 +299,6 @@ typedef struct glb_lb_policy {
   /** timeout in milliseconds for the LB call. 0 means no deadline. */
   int lb_call_timeout_ms;
 
-  /** timeout in milliseconds for before using fallback backend addresses.
-   * 0 means not using fallback. */
-  int lb_fallback_timeout_ms;
-
   /** for communicating with the LB server */
   grpc_channel *lb_channel;
 
@@ -330,9 +325,6 @@ typedef struct glb_lb_policy {
    * Otherwise, we delegate to the RR policy. */
   size_t serverlist_index;
 
-  /** stores the backend addresses from the resolver */
-  grpc_lb_addresses *fallback_backend_addresses;
-
   /** list of picks that are waiting on RR's policy connectivity */
   pending_pick *pending_picks;
 
@@ -353,9 +345,6 @@ typedef struct glb_lb_policy {
   /** is \a lb_call_retry_timer active? */
   bool retry_timer_active;
 
-  /** is \a lb_fallback_timer active? */
-  bool fallback_timer_active;
-
   /** called upon changes to the LB channel's connectivity. */
   grpc_closure lb_channel_on_connectivity_changed;
 
@@ -378,9 +367,6 @@ typedef struct glb_lb_policy {
   /* LB call retry timer callback. */
   grpc_closure lb_on_call_retry;
 
-  /* LB fallback timer callback. */
-  grpc_closure lb_on_fallback;
-
   grpc_call *lb_call; /* streaming call to the LB server, */
 
   grpc_metadata_array lb_initial_metadata_recv; /* initial MD from LB server */
@@ -404,9 +390,6 @@ typedef struct glb_lb_policy {
   /** LB call retry timer */
   grpc_timer lb_call_retry_timer;
 
-  /** LB fallback timer */
-  grpc_timer lb_fallback_timer;
-
   bool initial_request_sent;
   bool seen_initial_response;
 
@@ -553,32 +536,6 @@ static grpc_lb_addresses *process_serverlist_locked(
   return lb_addresses;
 }
 
-/* Returns the backend addresses extracted from the given addresses */
-static grpc_lb_addresses *extract_backend_addresses_locked(
-    grpc_exec_ctx *exec_ctx, const grpc_lb_addresses *addresses) {
-  /* first pass: count the number of backend addresses */
-  size_t num_backends = 0;
-  for (size_t i = 0; i < addresses->num_addresses; ++i) {
-    if (!addresses->addresses[i].is_balancer) {
-      ++num_backends;
-    }
-  }
-  /* second pass: actually populate the addresses and (empty) LB tokens */
-  grpc_lb_addresses *backend_addresses =
-      grpc_lb_addresses_create(num_backends, &lb_token_vtable);
-  size_t num_copied = 0;
-  for (size_t i = 0; i < addresses->num_addresses; ++i) {
-    if (addresses->addresses[i].is_balancer) continue;
-    const grpc_resolved_address *addr = &addresses->addresses[i].address;
-    grpc_lb_addresses_set_address(backend_addresses, num_copied, &addr->addr,
-                                  addr->len, false /* is_balancer */,
-                                  NULL /* balancer_name */,
-                                  (void *)GRPC_MDELEM_LB_TOKEN_EMPTY.payload);
-    ++num_copied;
-  }
-  return backend_addresses;
-}
-
 static void update_lb_connectivity_status_locked(
     grpc_exec_ctx *exec_ctx, glb_lb_policy *glb_policy,
     grpc_connectivity_state rr_state, grpc_error *rr_state_error) {
@@ -646,38 +603,35 @@ static bool pick_from_internal_rr_locked(
     grpc_exec_ctx *exec_ctx, glb_lb_policy *glb_policy,
     const grpc_lb_policy_pick_args *pick_args, bool force_async,
     grpc_connected_subchannel **target, wrapped_rr_closure_arg *wc_arg) {
-  // Check for drops if we are not using fallback backend addresses.
-  if (glb_policy->serverlist != NULL) {
-    // Look at the index into the serverlist to see if we should drop this call.
-    grpc_grpclb_server *server =
-        glb_policy->serverlist->servers[glb_policy->serverlist_index++];
-    if (glb_policy->serverlist_index == glb_policy->serverlist->num_servers) {
-      glb_policy->serverlist_index = 0;  // Wrap-around.
+  // Look at the index into the serverlist to see if we should drop this call.
+  grpc_grpclb_server *server =
+      glb_policy->serverlist->servers[glb_policy->serverlist_index++];
+  if (glb_policy->serverlist_index == glb_policy->serverlist->num_servers) {
+    glb_policy->serverlist_index = 0;  // Wrap-around.
+  }
+  if (server->drop) {
+    // Not using the RR policy, so unref it.
+    if (GRPC_TRACER_ON(grpc_lb_glb_trace)) {
+      gpr_log(GPR_INFO, "Unreffing RR for drop (0x%" PRIxPTR ")",
+              (intptr_t)wc_arg->rr_policy);
     }
-    if (server->drop) {
-      // Not using the RR policy, so unref it.
-      if (GRPC_TRACER_ON(grpc_lb_glb_trace)) {
-        gpr_log(GPR_INFO, "Unreffing RR for drop (0x%" PRIxPTR ")",
-                (intptr_t)wc_arg->rr_policy);
-      }
-      GRPC_LB_POLICY_UNREF(exec_ctx, wc_arg->rr_policy, "glb_pick_sync");
-      // Update client load reporting stats to indicate the number of
-      // dropped calls.  Note that we have to do this here instead of in
-      // the client_load_reporting filter, because we do not create a
-      // subchannel call (and therefore no client_load_reporting filter)
-      // for dropped calls.
-      grpc_grpclb_client_stats_add_call_dropped_locked(
-          server->load_balance_token, wc_arg->client_stats);
-      grpc_grpclb_client_stats_unref(wc_arg->client_stats);
-      if (force_async) {
-        GPR_ASSERT(wc_arg->wrapped_closure != NULL);
-        GRPC_CLOSURE_SCHED(exec_ctx, wc_arg->wrapped_closure, GRPC_ERROR_NONE);
-        gpr_free(wc_arg->free_when_done);
-        return false;
-      }
+    GRPC_LB_POLICY_UNREF(exec_ctx, wc_arg->rr_policy, "glb_pick_sync");
+    // Update client load reporting stats to indicate the number of
+    // dropped calls.  Note that we have to do this here instead of in
+    // the client_load_reporting filter, because we do not create a
+    // subchannel call (and therefore no client_load_reporting filter)
+    // for dropped calls.
+    grpc_grpclb_client_stats_add_call_dropped_locked(server->load_balance_token,
+                                                     wc_arg->client_stats);
+    grpc_grpclb_client_stats_unref(wc_arg->client_stats);
+    if (force_async) {
+      GPR_ASSERT(wc_arg->wrapped_closure != NULL);
+      GRPC_CLOSURE_SCHED(exec_ctx, wc_arg->wrapped_closure, GRPC_ERROR_NONE);
       gpr_free(wc_arg->free_when_done);
-      return true;
+      return false;
     }
+    gpr_free(wc_arg->free_when_done);
+    return true;
   }
   // Pick via the RR policy.
   const bool pick_done = grpc_lb_policy_pick_locked(
@@ -715,18 +669,8 @@ static bool pick_from_internal_rr_locked(
 
 static grpc_lb_policy_args *lb_policy_args_create(grpc_exec_ctx *exec_ctx,
                                                   glb_lb_policy *glb_policy) {
-  grpc_lb_addresses *addresses;
-  if (glb_policy->serverlist != NULL) {
-    GPR_ASSERT(glb_policy->serverlist->num_servers > 0);
-    addresses = process_serverlist_locked(exec_ctx, glb_policy->serverlist);
-  } else {
-    // If rr_handover_locked() is invoked when we haven't received any
-    // serverlist from the balancer, we use the fallback backends returned by
-    // the resolver. Note that the fallback backend list may be empty, in which
-    // case the new round_robin policy will keep the requested picks pending.
-    GPR_ASSERT(glb_policy->fallback_backend_addresses != NULL);
-    addresses = grpc_lb_addresses_copy(glb_policy->fallback_backend_addresses);
-  }
+  grpc_lb_addresses *addresses =
+      process_serverlist_locked(exec_ctx, glb_policy->serverlist);
   GPR_ASSERT(addresses != NULL);
   grpc_lb_policy_args *args = (grpc_lb_policy_args *)gpr_zalloc(sizeof(*args));
   args->client_channel_factory = glb_policy->cc_factory;
@@ -832,6 +776,8 @@ static void create_rr_locked(grpc_exec_ctx *exec_ctx, glb_lb_policy *glb_policy,
 /* glb_policy->rr_policy may be NULL (initial handover) */
 static void rr_handover_locked(grpc_exec_ctx *exec_ctx,
                                glb_lb_policy *glb_policy) {
+  GPR_ASSERT(glb_policy->serverlist != NULL &&
+             glb_policy->serverlist->num_servers > 0);
   if (glb_policy->shutting_down) return;
   grpc_lb_policy_args *args = lb_policy_args_create(exec_ctx, glb_policy);
   GPR_ASSERT(args != NULL);
@@ -980,9 +926,6 @@ static void glb_destroy(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol) {
   if (glb_policy->serverlist != NULL) {
     grpc_grpclb_destroy_serverlist(glb_policy->serverlist);
   }
-  if (glb_policy->fallback_backend_addresses != NULL) {
-    grpc_lb_addresses_destroy(exec_ctx, glb_policy->fallback_backend_addresses);
-  }
   grpc_fake_resolver_response_generator_unref(glb_policy->response_generator);
   grpc_subchannel_index_unref();
   if (glb_policy->pending_update_args != NULL) {
@@ -1124,28 +1067,10 @@ static void glb_cancel_picks_locked(grpc_exec_ctx *exec_ctx,
   GRPC_ERROR_UNREF(error);
 }
 
-static void lb_on_fallback_timer_locked(grpc_exec_ctx *exec_ctx, void *arg,
-                                        grpc_error *error);
 static void query_for_backends_locked(grpc_exec_ctx *exec_ctx,
                                       glb_lb_policy *glb_policy);
 static void start_picking_locked(grpc_exec_ctx *exec_ctx,
                                  glb_lb_policy *glb_policy) {
-  /* start a timer to fall back */
-  if (glb_policy->lb_fallback_timeout_ms > 0 &&
-      glb_policy->serverlist == NULL) {
-    gpr_timespec now = gpr_now(GPR_CLOCK_MONOTONIC);
-    gpr_timespec deadline = gpr_time_add(
-        now,
-        gpr_time_from_millis(glb_policy->lb_fallback_timeout_ms, GPR_TIMESPAN));
-    GRPC_LB_POLICY_WEAK_REF(&glb_policy->base, "grpclb_fallback_timer");
-    GRPC_CLOSURE_INIT(&glb_policy->lb_on_fallback, lb_on_fallback_timer_locked,
-                      glb_policy,
-                      grpc_combiner_scheduler(glb_policy->base.combiner));
-    glb_policy->fallback_timer_active = true;
-    grpc_timer_init(exec_ctx, &glb_policy->lb_fallback_timer, deadline,
-                    &glb_policy->lb_on_fallback, now);
-  }
-
   glb_policy->started_picking = true;
   gpr_backoff_reset(&glb_policy->lb_call_backoff_state);
   query_for_backends_locked(exec_ctx, glb_policy);
@@ -1600,15 +1525,6 @@ static void lb_on_response_received_locked(grpc_exec_ctx *exec_ctx, void *arg,
             if (glb_policy->serverlist != NULL) {
               /* dispose of the old serverlist */
               grpc_grpclb_destroy_serverlist(glb_policy->serverlist);
-            } else {
-              /* or dispose of the fallback */
-              grpc_lb_addresses_destroy(exec_ctx,
-                                        glb_policy->fallback_backend_addresses);
-              glb_policy->fallback_backend_addresses = NULL;
-              if (glb_policy->fallback_timer_active) {
-                grpc_timer_cancel(exec_ctx, &glb_policy->lb_fallback_timer);
-                glb_policy->fallback_timer_active = false;
-              }
             }
             /* and update the copy in the glb_lb_policy instance. This
              * serverlist instance will be destroyed either upon the next
@@ -1619,7 +1535,9 @@ static void lb_on_response_received_locked(grpc_exec_ctx *exec_ctx, void *arg,
           }
         } else {
           if (GRPC_TRACER_ON(grpc_lb_glb_trace)) {
-            gpr_log(GPR_INFO, "Received empty server list, ignoring.");
+            gpr_log(GPR_INFO,
+                    "Received empty server list. Picks will stay pending until "
+                    "a response with > 0 servers is received");
           }
           grpc_grpclb_destroy_serverlist(serverlist);
         }
@@ -1666,26 +1584,6 @@ static void lb_call_on_retry_timer_locked(grpc_exec_ctx *exec_ctx, void *arg,
   GRPC_LB_POLICY_WEAK_UNREF(exec_ctx, &glb_policy->base, "grpclb_retry_timer");
 }
 
-static void lb_on_fallback_timer_locked(grpc_exec_ctx *exec_ctx, void *arg,
-                                        grpc_error *error) {
-  glb_lb_policy *glb_policy = (glb_lb_policy *)arg;
-  /* If we receive a serverlist after the timer fires but before this callback
-   * actually runs, don't do anything. */
-  if (glb_policy->serverlist != NULL) return;
-  glb_policy->fallback_timer_active = false;
-  if (!glb_policy->shutting_down && error == GRPC_ERROR_NONE) {
-    if (GRPC_TRACER_ON(grpc_lb_glb_trace)) {
-      gpr_log(GPR_INFO,
-              "Falling back to use backends from resolver (grpclb %p)",
-              (void *)glb_policy);
-    }
-    GPR_ASSERT(glb_policy->fallback_backend_addresses != NULL);
-    rr_handover_locked(exec_ctx, glb_policy);
-  }
-  GRPC_LB_POLICY_WEAK_UNREF(exec_ctx, &glb_policy->base,
-                            "grpclb_fallback_timer");
-}
-
 static void lb_on_server_status_received_locked(grpc_exec_ctx *exec_ctx,
                                                 void *arg, grpc_error *error) {
   glb_lb_policy *glb_policy = (glb_lb_policy *)arg;
@@ -1806,17 +1704,6 @@ static void glb_update_locked(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,
         &glb_policy->lb_channel_connectivity,
         &glb_policy->lb_channel_on_connectivity_changed, NULL);
   }
-
-  // Propagate update to fallback_backend_addresses if a non-empty serverlist
-  // hasn't been received from the balancer.
-  if (glb_policy->serverlist == NULL) {
-    grpc_lb_addresses_destroy(exec_ctx, glb_policy->fallback_backend_addresses);
-    glb_policy->fallback_backend_addresses =
-        extract_backend_addresses_locked(exec_ctx, addresses);
-    if (glb_policy->rr_policy != NULL) {
-      rr_handover_locked(exec_ctx, glb_policy);
-    }
-  }
 }
 
 // Invoked as part of the update process. It continues watching the LB channel
@@ -1899,7 +1786,13 @@ static const grpc_lb_policy_vtable glb_lb_policy_vtable = {
 static grpc_lb_policy *glb_create(grpc_exec_ctx *exec_ctx,
                                   grpc_lb_policy_factory *factory,
                                   grpc_lb_policy_args *args) {
-  /* Count the number of gRPC-LB addresses. There must be at least one. */
+  /* Count the number of gRPC-LB addresses. There must be at least one.
+   * TODO(roth): For now, we ignore non-balancer addresses, but in the
+   * future, we may change the behavior such that we fall back to using
+   * the non-balancer addresses if we cannot reach any balancers. In the
+   * fallback case, we should use the LB policy indicated by
+   * GRPC_ARG_LB_POLICY_NAME (although if that specifies grpclb or is
+   * unset, we should default to pick_first). */
   const grpc_arg *arg =
       grpc_channel_args_find(args->args, GRPC_ARG_LB_ADDRESSES);
   if (arg == NULL || arg->type != GRPC_ARG_POINTER) {
@@ -1935,11 +1828,6 @@ static grpc_lb_policy *glb_create(grpc_exec_ctx *exec_ctx,
   glb_policy->lb_call_timeout_ms =
       grpc_channel_arg_get_integer(arg, (grpc_integer_options){0, 0, INT_MAX});
 
-  arg = grpc_channel_args_find(args->args, GRPC_ARG_GRPCLB_FALLBACK_TIMEOUT_MS);
-  glb_policy->lb_fallback_timeout_ms = grpc_channel_arg_get_integer(
-      arg, (grpc_integer_options){GRPC_GRPCLB_DEFAULT_FALLBACK_TIMEOUT_MS, 0,
-                                  INT_MAX});
-
   // Make sure that GRPC_ARG_LB_POLICY_NAME is set in channel args,
   // since we use this to trigger the client_load_reporting filter.
   grpc_arg new_arg =
@@ -1948,11 +1836,6 @@ static grpc_lb_policy *glb_create(grpc_exec_ctx *exec_ctx,
   glb_policy->args = grpc_channel_args_copy_and_add_and_remove(
       args->args, args_to_remove, GPR_ARRAY_SIZE(args_to_remove), &new_arg, 1);
 
-  /* Extract the backend addresses (may be empty) from the resolver for
-   * fallback. */
-  glb_policy->fallback_backend_addresses =
-      extract_backend_addresses_locked(exec_ctx, addresses);
-
   /* Create a client channel over them to communicate with a LB service */
   glb_policy->response_generator =
       grpc_fake_resolver_response_generator_create();
diff --git a/src/core/ext/filters/client_channel/lb_policy_factory.c b/src/core/ext/filters/client_channel/lb_policy_factory.c
index a9a00f5b2b..acf5929746 100644
--- a/src/core/ext/filters/client_channel/lb_policy_factory.c
+++ b/src/core/ext/filters/client_channel/lb_policy_factory.c
@@ -56,7 +56,7 @@ grpc_lb_addresses* grpc_lb_addresses_copy(const grpc_lb_addresses* addresses) {
 }
 
 void grpc_lb_addresses_set_address(grpc_lb_addresses* addresses, size_t index,
-                                   const void* address, size_t address_len,
+                                   void* address, size_t address_len,
                                    bool is_balancer, const char* balancer_name,
                                    void* user_data) {
   GPR_ASSERT(index < addresses->num_addresses);
diff --git a/src/core/ext/filters/client_channel/lb_policy_factory.h b/src/core/ext/filters/client_channel/lb_policy_factory.h
index cf0f8cb615..9d9fb143df 100644
--- a/src/core/ext/filters/client_channel/lb_policy_factory.h
+++ b/src/core/ext/filters/client_channel/lb_policy_factory.h
@@ -73,7 +73,7 @@ grpc_lb_addresses *grpc_lb_addresses_copy(const grpc_lb_addresses *addresses);
  * \a address is a socket address of length \a address_len.
  * Takes ownership of \a balancer_name. */
 void grpc_lb_addresses_set_address(grpc_lb_addresses *addresses, size_t index,
-                                   const void *address, size_t address_len,
+                                   void *address, size_t address_len,
                                    bool is_balancer, const char *balancer_name,
                                    void *user_data);
 
diff --git a/src/core/ext/filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.c b/src/core/ext/filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.c
index b87a3b7082..371c59b8cf 100644
--- a/src/core/ext/filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.c
+++ b/src/core/ext/filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.c
@@ -204,7 +204,7 @@ static char *choose_service_config(char *service_config_choice_json) {
         int random_pct = rand() % 100;
         int percentage;
         if (sscanf(field->value, "%d", &percentage) != 1 ||
-            random_pct > percentage) {
+            random_pct > percentage || percentage == 0) {
           service_config_json = NULL;
           break;
         }
diff --git a/src/core/ext/transport/chttp2/transport/chttp2_transport.c b/src/core/ext/transport/chttp2/transport/chttp2_transport.c
index 930fa805a0..79a9ed827f 100644
--- a/src/core/ext/transport/chttp2/transport/chttp2_transport.c
+++ b/src/core/ext/transport/chttp2/transport/chttp2_transport.c
@@ -144,10 +144,11 @@ static void finish_bdp_ping_locked(grpc_exec_ctx *exec_ctx, void *tp,
 
 static void cancel_pings(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
                          grpc_error *error);
-static void send_ping_locked(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
-                             grpc_chttp2_ping_type ping_type,
-                             grpc_closure *on_initiate,
-                             grpc_closure *on_complete);
+static void send_ping_locked(
+    grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
+    grpc_chttp2_ping_type ping_type, grpc_closure *on_initiate,
+    grpc_closure *on_complete,
+    grpc_chttp2_initiate_write_reason initiate_write_reason);
 static void retry_initiate_ping_locked(grpc_exec_ctx *exec_ctx, void *tp,
                                        grpc_error *error);
 
@@ -346,7 +347,6 @@ static void init_transport(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
   if (is_client) {
     grpc_slice_buffer_add(&t->outbuf, grpc_slice_from_copied_string(
                                           GRPC_CHTTP2_CLIENT_CONNECT_STRING));
-    grpc_chttp2_initiate_write(exec_ctx, t, "initial_write");
   }
 
   /* configure http2 the way we like it */
@@ -578,7 +578,8 @@ static void init_transport(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
     t->keepalive_state = GRPC_CHTTP2_KEEPALIVE_STATE_DISABLED;
   }
 
-  grpc_chttp2_initiate_write(exec_ctx, t, "init");
+  grpc_chttp2_initiate_write(exec_ctx, t,
+                             GRPC_CHTTP2_INITIATE_WRITE_INITIAL_WRITE);
   post_benign_reclaimer(exec_ctx, t);
 }
 
@@ -846,13 +847,91 @@ static void set_write_state(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
   }
 }
 
+static void inc_initiate_write_reason(
+    grpc_exec_ctx *exec_ctx, grpc_chttp2_initiate_write_reason reason) {
+  switch (reason) {
+    case GRPC_CHTTP2_INITIATE_WRITE_INITIAL_WRITE:
+      GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_INITIAL_WRITE(exec_ctx);
+      break;
+    case GRPC_CHTTP2_INITIATE_WRITE_START_NEW_STREAM:
+      GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_START_NEW_STREAM(exec_ctx);
+      break;
+    case GRPC_CHTTP2_INITIATE_WRITE_SEND_MESSAGE:
+      GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_SEND_MESSAGE(exec_ctx);
+      break;
+    case GRPC_CHTTP2_INITIATE_WRITE_SEND_INITIAL_METADATA:
+      GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_SEND_INITIAL_METADATA(
+          exec_ctx);
+      break;
+    case GRPC_CHTTP2_INITIATE_WRITE_SEND_TRAILING_METADATA:
+      GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_SEND_TRAILING_METADATA(
+          exec_ctx);
+      break;
+    case GRPC_CHTTP2_INITIATE_WRITE_RETRY_SEND_PING:
+      GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_RETRY_SEND_PING(exec_ctx);
+      break;
+    case GRPC_CHTTP2_INITIATE_WRITE_CONTINUE_PINGS:
+      GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_CONTINUE_PINGS(exec_ctx);
+      break;
+    case GRPC_CHTTP2_INITIATE_WRITE_GOAWAY_SENT:
+      GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_GOAWAY_SENT(exec_ctx);
+      break;
+    case GRPC_CHTTP2_INITIATE_WRITE_RST_STREAM:
+      GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_RST_STREAM(exec_ctx);
+      break;
+    case GRPC_CHTTP2_INITIATE_WRITE_CLOSE_FROM_API:
+      GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_CLOSE_FROM_API(exec_ctx);
+      break;
+    case GRPC_CHTTP2_INITIATE_WRITE_STREAM_FLOW_CONTROL:
+      GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_STREAM_FLOW_CONTROL(exec_ctx);
+      break;
+    case GRPC_CHTTP2_INITIATE_WRITE_TRANSPORT_FLOW_CONTROL:
+      GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_TRANSPORT_FLOW_CONTROL(
+          exec_ctx);
+      break;
+    case GRPC_CHTTP2_INITIATE_WRITE_SEND_SETTINGS:
+      GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_SEND_SETTINGS(exec_ctx);
+      break;
+    case GRPC_CHTTP2_INITIATE_WRITE_BDP_ESTIMATOR_PING:
+      GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_BDP_ESTIMATOR_PING(exec_ctx);
+      break;
+    case GRPC_CHTTP2_INITIATE_WRITE_FLOW_CONTROL_UNSTALLED_BY_SETTING:
+      GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_FLOW_CONTROL_UNSTALLED_BY_SETTING(
+          exec_ctx);
+      break;
+    case GRPC_CHTTP2_INITIATE_WRITE_FLOW_CONTROL_UNSTALLED_BY_UPDATE:
+      GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_FLOW_CONTROL_UNSTALLED_BY_UPDATE(
+          exec_ctx);
+      break;
+    case GRPC_CHTTP2_INITIATE_WRITE_APPLICATION_PING:
+      GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_APPLICATION_PING(exec_ctx);
+      break;
+    case GRPC_CHTTP2_INITIATE_WRITE_KEEPALIVE_PING:
+      GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_KEEPALIVE_PING(exec_ctx);
+      break;
+    case GRPC_CHTTP2_INITIATE_WRITE_TRANSPORT_FLOW_CONTROL_UNSTALLED:
+      GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_TRANSPORT_FLOW_CONTROL_UNSTALLED(
+          exec_ctx);
+      break;
+    case GRPC_CHTTP2_INITIATE_WRITE_PING_RESPONSE:
+      GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_PING_RESPONSE(exec_ctx);
+      break;
+    case GRPC_CHTTP2_INITIATE_WRITE_FORCE_RST_STREAM:
+      GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_FORCE_RST_STREAM(exec_ctx);
+      break;
+  }
+}
+
 void grpc_chttp2_initiate_write(grpc_exec_ctx *exec_ctx,
-                                grpc_chttp2_transport *t, const char *reason) {
+                                grpc_chttp2_transport *t,
+                                grpc_chttp2_initiate_write_reason reason) {
   GPR_TIMER_BEGIN("grpc_chttp2_initiate_write", 0);
 
   switch (t->write_state) {
     case GRPC_CHTTP2_WRITE_STATE_IDLE:
-      set_write_state(exec_ctx, t, GRPC_CHTTP2_WRITE_STATE_WRITING, reason);
+      inc_initiate_write_reason(exec_ctx, reason);
+      set_write_state(exec_ctx, t, GRPC_CHTTP2_WRITE_STATE_WRITING,
+                      grpc_chttp2_initiate_write_reason_string(reason));
       t->is_first_write_in_batch = true;
       GRPC_CHTTP2_REF_TRANSPORT(t, "writing");
       GRPC_CLOSURE_SCHED(
@@ -864,7 +943,7 @@ void grpc_chttp2_initiate_write(grpc_exec_ctx *exec_ctx,
       break;
     case GRPC_CHTTP2_WRITE_STATE_WRITING:
       set_write_state(exec_ctx, t, GRPC_CHTTP2_WRITE_STATE_WRITING_WITH_MORE,
-                      reason);
+                      grpc_chttp2_initiate_write_reason_string(reason));
       break;
     case GRPC_CHTTP2_WRITE_STATE_WRITING_WITH_MORE:
       break;
@@ -872,16 +951,12 @@ void grpc_chttp2_initiate_write(grpc_exec_ctx *exec_ctx,
   GPR_TIMER_END("grpc_chttp2_initiate_write", 0);
 }
 
-void grpc_chttp2_become_writable(grpc_exec_ctx *exec_ctx,
-                                 grpc_chttp2_transport *t,
-                                 grpc_chttp2_stream *s,
-                                 bool also_initiate_write, const char *reason) {
+void grpc_chttp2_mark_stream_writable(grpc_exec_ctx *exec_ctx,
+                                      grpc_chttp2_transport *t,
+                                      grpc_chttp2_stream *s) {
   if (!t->closed && grpc_chttp2_list_add_writable_stream(t, s)) {
     GRPC_CHTTP2_STREAM_REF(s, "chttp2_writing:become");
   }
-  if (also_initiate_write) {
-    grpc_chttp2_initiate_write(exec_ctx, t, reason);
-  }
 }
 
 static grpc_closure_scheduler *write_scheduler(grpc_chttp2_transport *t,
@@ -1105,7 +1180,9 @@ static void maybe_start_some_streams(grpc_exec_ctx *exec_ctx,
 
     grpc_chttp2_stream_map_add(&t->stream_map, s->id, s);
     post_destructive_reclaimer(exec_ctx, t);
-    grpc_chttp2_become_writable(exec_ctx, t, s, true, "new_stream");
+    grpc_chttp2_mark_stream_writable(exec_ctx, t, s);
+    grpc_chttp2_initiate_write(exec_ctx, t,
+                               GRPC_CHTTP2_INITIATE_WRITE_START_NEW_STREAM);
   }
   /* cancel out streams that will never be started */
   while (t->next_stream_id >= MAX_CLIENT_STREAM_ID &&
@@ -1202,7 +1279,9 @@ static void maybe_become_writable_due_to_send_msg(grpc_exec_ctx *exec_ctx,
                                                   grpc_chttp2_stream *s) {
   if (s->id != 0 && (!s->write_buffering ||
                      s->flow_controlled_buffer.length > t->write_buffer_size)) {
-    grpc_chttp2_become_writable(exec_ctx, t, s, true, "op.send_message");
+    grpc_chttp2_mark_stream_writable(exec_ctx, t, s);
+    grpc_chttp2_initiate_write(exec_ctx, t,
+                               GRPC_CHTTP2_INITIATE_WRITE_SEND_MESSAGE);
   }
 }
 
@@ -1404,14 +1483,13 @@ static void perform_stream_op_locked(grpc_exec_ctx *exec_ctx, void *stream_op,
           }
         } else {
           GPR_ASSERT(s->id != 0);
-          bool initiate_write = true;
-          if (op->send_message &&
-              (op->payload->send_message.send_message->flags &
-               GRPC_WRITE_BUFFER_HINT)) {
-            initiate_write = false;
+          grpc_chttp2_mark_stream_writable(exec_ctx, t, s);
+          if (!(op->send_message &&
+                (op->payload->send_message.send_message->flags &
+                 GRPC_WRITE_BUFFER_HINT))) {
+            grpc_chttp2_initiate_write(
+                exec_ctx, t, GRPC_CHTTP2_INITIATE_WRITE_SEND_INITIAL_METADATA);
           }
-          grpc_chttp2_become_writable(exec_ctx, t, s, initiate_write,
-                                      "op.send_initial_metadata");
         }
       } else {
         s->send_initial_metadata = NULL;
@@ -1519,8 +1597,9 @@ static void perform_stream_op_locked(grpc_exec_ctx *exec_ctx, void *stream_op,
       } else if (s->id != 0) {
         /* TODO(ctiller): check if there's flow control for any outstanding
            bytes before going writable */
-        grpc_chttp2_become_writable(exec_ctx, t, s, true,
-                                    "op.send_trailing_metadata");
+        grpc_chttp2_mark_stream_writable(exec_ctx, t, s);
+        grpc_chttp2_initiate_write(
+            exec_ctx, t, GRPC_CHTTP2_INITIATE_WRITE_SEND_TRAILING_METADATA);
       }
     }
   }
@@ -1632,15 +1711,17 @@ static void cancel_pings(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
   GRPC_ERROR_UNREF(error);
 }
 
-static void send_ping_locked(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
-                             grpc_chttp2_ping_type ping_type,
-                             grpc_closure *on_initiate, grpc_closure *on_ack) {
+static void send_ping_locked(
+    grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
+    grpc_chttp2_ping_type ping_type, grpc_closure *on_initiate,
+    grpc_closure *on_ack,
+    grpc_chttp2_initiate_write_reason initiate_write_reason) {
   grpc_chttp2_ping_queue *pq = &t->ping_queues[ping_type];
   grpc_closure_list_append(&pq->lists[GRPC_CHTTP2_PCL_INITIATE], on_initiate,
                            GRPC_ERROR_NONE);
   if (grpc_closure_list_append(&pq->lists[GRPC_CHTTP2_PCL_NEXT], on_ack,
                                GRPC_ERROR_NONE)) {
-    grpc_chttp2_initiate_write(exec_ctx, t, "send_ping");
+    grpc_chttp2_initiate_write(exec_ctx, t, initiate_write_reason);
   }
 }
 
@@ -1648,7 +1729,8 @@ 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, "retry_send_ping");
+  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,
@@ -1663,7 +1745,8 @@ void grpc_chttp2_ack_ping(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
   }
   GRPC_CLOSURE_LIST_SCHED(exec_ctx, &pq->lists[GRPC_CHTTP2_PCL_INFLIGHT]);
   if (!grpc_closure_list_empty(pq->lists[GRPC_CHTTP2_PCL_NEXT])) {
-    grpc_chttp2_initiate_write(exec_ctx, t, "continue_pings");
+    grpc_chttp2_initiate_write(exec_ctx, t,
+                               GRPC_CHTTP2_INITIATE_WRITE_CONTINUE_PINGS);
   }
 }
 
@@ -1676,7 +1759,8 @@ static void send_goaway(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
                         &slice, &http_error);
   grpc_chttp2_goaway_append(t->last_new_stream_id, (uint32_t)http_error,
                             grpc_slice_ref_internal(slice), &t->qbuf);
-  grpc_chttp2_initiate_write(exec_ctx, t, "goaway_sent");
+  grpc_chttp2_initiate_write(exec_ctx, t,
+                             GRPC_CHTTP2_INITIATE_WRITE_GOAWAY_SENT);
   GRPC_ERROR_UNREF(error);
 }
 
@@ -1723,7 +1807,8 @@ static void perform_transport_op_locked(grpc_exec_ctx *exec_ctx,
 
   if (op->send_ping) {
     send_ping_locked(exec_ctx, t, GRPC_CHTTP2_PING_ON_NEXT_WRITE, NULL,
-                     op->send_ping);
+                     op->send_ping,
+                     GRPC_CHTTP2_INITIATE_WRITE_APPLICATION_PING);
   }
 
   if (op->on_connectivity_state_change != NULL) {
@@ -1968,7 +2053,8 @@ void grpc_chttp2_cancel_stream(grpc_exec_ctx *exec_ctx,
       grpc_slice_buffer_add(
           &t->qbuf, grpc_chttp2_rst_stream_create(s->id, (uint32_t)http_error,
                                                   &s->stats.outgoing));
-      grpc_chttp2_initiate_write(exec_ctx, t, "rst_stream");
+      grpc_chttp2_initiate_write(exec_ctx, t,
+                                 GRPC_CHTTP2_INITIATE_WRITE_RST_STREAM);
     }
   }
   if (due_to_error != GRPC_ERROR_NONE && !s->seen_error) {
@@ -2289,7 +2375,8 @@ static void close_from_api(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
                                               &s->stats.outgoing));
 
   grpc_chttp2_mark_stream_closed(exec_ctx, t, s, 1, 1, error);
-  grpc_chttp2_initiate_write(exec_ctx, t, "close_from_api");
+  grpc_chttp2_initiate_write(exec_ctx, t,
+                             GRPC_CHTTP2_INITIATE_WRITE_CLOSE_FROM_API);
 }
 
 typedef struct {
@@ -2324,19 +2411,20 @@ void grpc_chttp2_act_on_flowctl_action(grpc_exec_ctx *exec_ctx,
     case GRPC_CHTTP2_FLOWCTL_NO_ACTION_NEEDED:
       break;
     case GRPC_CHTTP2_FLOWCTL_UPDATE_IMMEDIATELY:
-      grpc_chttp2_become_writable(exec_ctx, t, s, true,
-                                  "immediate stream flowctl");
+      grpc_chttp2_mark_stream_writable(exec_ctx, t, s);
+      grpc_chttp2_initiate_write(
+          exec_ctx, t, GRPC_CHTTP2_INITIATE_WRITE_STREAM_FLOW_CONTROL);
       break;
     case GRPC_CHTTP2_FLOWCTL_QUEUE_UPDATE:
-      grpc_chttp2_become_writable(exec_ctx, t, s, false,
-                                  "queue stream flowctl");
+      grpc_chttp2_mark_stream_writable(exec_ctx, t, s);
       break;
   }
   switch (action.send_transport_update) {
     case GRPC_CHTTP2_FLOWCTL_NO_ACTION_NEEDED:
       break;
     case GRPC_CHTTP2_FLOWCTL_UPDATE_IMMEDIATELY:
-      grpc_chttp2_initiate_write(exec_ctx, t, "immediate transport flowctl");
+      grpc_chttp2_initiate_write(
+          exec_ctx, t, GRPC_CHTTP2_INITIATE_WRITE_TRANSPORT_FLOW_CONTROL);
       break;
     // this is the same as no action b/c every time the transport enters the
     // writing path it will maybe do an update
@@ -2354,7 +2442,8 @@ void grpc_chttp2_act_on_flowctl_action(grpc_exec_ctx *exec_ctx,
                            (uint32_t)action.max_frame_size);
     }
     if (action.send_setting_update == GRPC_CHTTP2_FLOWCTL_UPDATE_IMMEDIATELY) {
-      grpc_chttp2_initiate_write(exec_ctx, t, "immediate setting update");
+      grpc_chttp2_initiate_write(exec_ctx, t,
+                                 GRPC_CHTTP2_INITIATE_WRITE_SEND_SETTINGS);
     }
   }
   if (action.need_ping) {
@@ -2362,7 +2451,8 @@ void grpc_chttp2_act_on_flowctl_action(grpc_exec_ctx *exec_ctx,
     grpc_bdp_estimator_schedule_ping(&t->flow_control.bdp_estimator);
     send_ping_locked(exec_ctx, t,
                      GRPC_CHTTP2_PING_BEFORE_TRANSPORT_WINDOW_UPDATE,
-                     &t->start_bdp_ping_locked, &t->finish_bdp_ping_locked);
+                     &t->start_bdp_ping_locked, &t->finish_bdp_ping_locked,
+                     GRPC_CHTTP2_INITIATE_WRITE_BDP_ESTIMATOR_PING);
   }
 }
 
@@ -2441,7 +2531,10 @@ static void read_action_locked(grpc_exec_ctx *exec_ctx, void *tp,
       if (t->flow_control.initial_window_update > 0) {
         grpc_chttp2_stream *s;
         while (grpc_chttp2_list_pop_stalled_by_stream(t, &s)) {
-          grpc_chttp2_become_writable(exec_ctx, t, s, true, "unstalled");
+          grpc_chttp2_mark_stream_writable(exec_ctx, t, s);
+          grpc_chttp2_initiate_write(
+              exec_ctx, t,
+              GRPC_CHTTP2_INITIATE_WRITE_FLOW_CONTROL_UNSTALLED_BY_SETTING);
         }
       }
       t->flow_control.initial_window_update = 0;
@@ -2556,7 +2649,8 @@ static void init_keepalive_ping_locked(grpc_exec_ctx *exec_ctx, void *arg,
       GRPC_CHTTP2_REF_TRANSPORT(t, "keepalive ping end");
       send_ping_locked(exec_ctx, t, GRPC_CHTTP2_PING_ON_NEXT_WRITE,
                        &t->start_keepalive_ping_locked,
-                       &t->finish_keepalive_ping_locked);
+                       &t->finish_keepalive_ping_locked,
+                       GRPC_CHTTP2_INITIATE_WRITE_KEEPALIVE_PING);
     } else {
       GRPC_CHTTP2_REF_TRANSPORT(t, "init keepalive ping");
       grpc_timer_init(
@@ -3017,6 +3111,56 @@ static void destructive_reclaimer_locked(grpc_exec_ctx *exec_ctx, void *arg,
 /*******************************************************************************
  * MONITORING
  */
+
+const char *grpc_chttp2_initiate_write_reason_string(
+    grpc_chttp2_initiate_write_reason reason) {
+  switch (reason) {
+    case GRPC_CHTTP2_INITIATE_WRITE_INITIAL_WRITE:
+      return "INITIAL_WRITE";
+    case GRPC_CHTTP2_INITIATE_WRITE_START_NEW_STREAM:
+      return "START_NEW_STREAM";
+    case GRPC_CHTTP2_INITIATE_WRITE_SEND_MESSAGE:
+      return "SEND_MESSAGE";
+    case GRPC_CHTTP2_INITIATE_WRITE_SEND_INITIAL_METADATA:
+      return "SEND_INITIAL_METADATA";
+    case GRPC_CHTTP2_INITIATE_WRITE_SEND_TRAILING_METADATA:
+      return "SEND_TRAILING_METADATA";
+    case GRPC_CHTTP2_INITIATE_WRITE_RETRY_SEND_PING:
+      return "RETRY_SEND_PING";
+    case GRPC_CHTTP2_INITIATE_WRITE_CONTINUE_PINGS:
+      return "CONTINUE_PINGS";
+    case GRPC_CHTTP2_INITIATE_WRITE_GOAWAY_SENT:
+      return "GOAWAY_SENT";
+    case GRPC_CHTTP2_INITIATE_WRITE_RST_STREAM:
+      return "RST_STREAM";
+    case GRPC_CHTTP2_INITIATE_WRITE_CLOSE_FROM_API:
+      return "CLOSE_FROM_API";
+    case GRPC_CHTTP2_INITIATE_WRITE_STREAM_FLOW_CONTROL:
+      return "STREAM_FLOW_CONTROL";
+    case GRPC_CHTTP2_INITIATE_WRITE_TRANSPORT_FLOW_CONTROL:
+      return "TRANSPORT_FLOW_CONTROL";
+    case GRPC_CHTTP2_INITIATE_WRITE_SEND_SETTINGS:
+      return "SEND_SETTINGS";
+    case GRPC_CHTTP2_INITIATE_WRITE_BDP_ESTIMATOR_PING:
+      return "BDP_ESTIMATOR_PING";
+    case GRPC_CHTTP2_INITIATE_WRITE_FLOW_CONTROL_UNSTALLED_BY_SETTING:
+      return "FLOW_CONTROL_UNSTALLED_BY_SETTING";
+    case GRPC_CHTTP2_INITIATE_WRITE_FLOW_CONTROL_UNSTALLED_BY_UPDATE:
+      return "FLOW_CONTROL_UNSTALLED_BY_UPDATE";
+    case GRPC_CHTTP2_INITIATE_WRITE_APPLICATION_PING:
+      return "APPLICATION_PING";
+    case GRPC_CHTTP2_INITIATE_WRITE_KEEPALIVE_PING:
+      return "KEEPALIVE_PING";
+    case GRPC_CHTTP2_INITIATE_WRITE_TRANSPORT_FLOW_CONTROL_UNSTALLED:
+      return "TRANSPORT_FLOW_CONTROL_UNSTALLED";
+    case GRPC_CHTTP2_INITIATE_WRITE_PING_RESPONSE:
+      return "PING_RESPONSE";
+    case GRPC_CHTTP2_INITIATE_WRITE_FORCE_RST_STREAM:
+      return "FORCE_RST_STREAM";
+  }
+  GPR_UNREACHABLE_CODE(return "unknown");
+}
+
 static grpc_endpoint *chttp2_get_endpoint(grpc_exec_ctx *exec_ctx,
                                           grpc_transport *t) {
   return ((grpc_chttp2_transport *)t)->ep;
diff --git a/src/core/ext/transport/chttp2/transport/frame_ping.c b/src/core/ext/transport/chttp2/transport/frame_ping.c
index 582fd7bfaa..81bd02ae70 100644
--- a/src/core/ext/transport/chttp2/transport/frame_ping.c
+++ b/src/core/ext/transport/chttp2/transport/frame_ping.c
@@ -117,7 +117,8 @@ grpc_error *grpc_chttp2_ping_parser_parse(grpc_exec_ctx *exec_ctx, void *parser,
               t->ping_acks, t->ping_ack_capacity * sizeof(*t->ping_acks));
         }
         t->ping_acks[t->ping_ack_count++] = p->opaque_8bytes;
-        grpc_chttp2_initiate_write(exec_ctx, t, "ping response");
+        grpc_chttp2_initiate_write(exec_ctx, t,
+                                   GRPC_CHTTP2_INITIATE_WRITE_PING_RESPONSE);
       }
     }
   }
diff --git a/src/core/ext/transport/chttp2/transport/frame_window_update.c b/src/core/ext/transport/chttp2/transport/frame_window_update.c
index c94f7725bf..c9ab8d1b50 100644
--- a/src/core/ext/transport/chttp2/transport/frame_window_update.c
+++ b/src/core/ext/transport/chttp2/transport/frame_window_update.c
@@ -99,8 +99,10 @@ grpc_error *grpc_chttp2_window_update_parser_parse(
         grpc_chttp2_flowctl_recv_stream_update(
             &t->flow_control, &s->flow_control, received_update);
         if (grpc_chttp2_list_remove_stalled_by_stream(t, s)) {
-          grpc_chttp2_become_writable(exec_ctx, t, s, true,
-                                      "stream.read_flow_control");
+          grpc_chttp2_mark_stream_writable(exec_ctx, t, s);
+          grpc_chttp2_initiate_write(
+              exec_ctx, t,
+              GRPC_CHTTP2_INITIATE_WRITE_FLOW_CONTROL_UNSTALLED_BY_UPDATE);
         }
       }
     } else {
@@ -109,7 +111,9 @@ grpc_error *grpc_chttp2_window_update_parser_parse(
                                                 received_update);
       bool is_zero = t->flow_control.remote_window <= 0;
       if (was_zero && !is_zero) {
-        grpc_chttp2_initiate_write(exec_ctx, t, "new_global_flow_control");
+        grpc_chttp2_initiate_write(
+            exec_ctx, t,
+            GRPC_CHTTP2_INITIATE_WRITE_TRANSPORT_FLOW_CONTROL_UNSTALLED);
       }
     }
   }
diff --git a/src/core/ext/transport/chttp2/transport/hpack_parser.c b/src/core/ext/transport/chttp2/transport/hpack_parser.c
index 82ff2c8e2c..901e7413c0 100644
--- a/src/core/ext/transport/chttp2/transport/hpack_parser.c
+++ b/src/core/ext/transport/chttp2/transport/hpack_parser.c
@@ -1649,7 +1649,8 @@ static void force_client_rst_stream(grpc_exec_ctx *exec_ctx, void *sp,
     grpc_slice_buffer_add(
         &t->qbuf, grpc_chttp2_rst_stream_create(s->id, GRPC_HTTP2_NO_ERROR,
                                                 &s->stats.outgoing));
-    grpc_chttp2_initiate_write(exec_ctx, t, "force_rst_stream");
+    grpc_chttp2_initiate_write(exec_ctx, t,
+                               GRPC_CHTTP2_INITIATE_WRITE_FORCE_RST_STREAM);
     grpc_chttp2_mark_stream_closed(exec_ctx, t, s, true, true, GRPC_ERROR_NONE);
   }
   GRPC_CHTTP2_STREAM_UNREF(exec_ctx, s, "final_rst");
diff --git a/src/core/ext/transport/chttp2/transport/internal.h b/src/core/ext/transport/chttp2/transport/internal.h
index 0fbedd1e56..c2dfce7c9c 100644
--- a/src/core/ext/transport/chttp2/transport/internal.h
+++ b/src/core/ext/transport/chttp2/transport/internal.h
@@ -79,6 +79,33 @@ typedef enum {
   GRPC_CHTTP2_PCL_COUNT /* must be last */
 } grpc_chttp2_ping_closure_list;
 
+typedef enum {
+  GRPC_CHTTP2_INITIATE_WRITE_INITIAL_WRITE,
+  GRPC_CHTTP2_INITIATE_WRITE_START_NEW_STREAM,
+  GRPC_CHTTP2_INITIATE_WRITE_SEND_MESSAGE,
+  GRPC_CHTTP2_INITIATE_WRITE_SEND_INITIAL_METADATA,
+  GRPC_CHTTP2_INITIATE_WRITE_SEND_TRAILING_METADATA,
+  GRPC_CHTTP2_INITIATE_WRITE_RETRY_SEND_PING,
+  GRPC_CHTTP2_INITIATE_WRITE_CONTINUE_PINGS,
+  GRPC_CHTTP2_INITIATE_WRITE_GOAWAY_SENT,
+  GRPC_CHTTP2_INITIATE_WRITE_RST_STREAM,
+  GRPC_CHTTP2_INITIATE_WRITE_CLOSE_FROM_API,
+  GRPC_CHTTP2_INITIATE_WRITE_STREAM_FLOW_CONTROL,
+  GRPC_CHTTP2_INITIATE_WRITE_TRANSPORT_FLOW_CONTROL,
+  GRPC_CHTTP2_INITIATE_WRITE_SEND_SETTINGS,
+  GRPC_CHTTP2_INITIATE_WRITE_BDP_ESTIMATOR_PING,
+  GRPC_CHTTP2_INITIATE_WRITE_FLOW_CONTROL_UNSTALLED_BY_SETTING,
+  GRPC_CHTTP2_INITIATE_WRITE_FLOW_CONTROL_UNSTALLED_BY_UPDATE,
+  GRPC_CHTTP2_INITIATE_WRITE_APPLICATION_PING,
+  GRPC_CHTTP2_INITIATE_WRITE_KEEPALIVE_PING,
+  GRPC_CHTTP2_INITIATE_WRITE_TRANSPORT_FLOW_CONTROL_UNSTALLED,
+  GRPC_CHTTP2_INITIATE_WRITE_PING_RESPONSE,
+  GRPC_CHTTP2_INITIATE_WRITE_FORCE_RST_STREAM,
+} grpc_chttp2_initiate_write_reason;
+
+const char *grpc_chttp2_initiate_write_reason_string(
+    grpc_chttp2_initiate_write_reason reason);
+
 typedef struct {
   grpc_closure_list lists[GRPC_CHTTP2_PCL_COUNT];
   uint64_t inflight_id;
@@ -599,7 +626,8 @@ struct grpc_chttp2_stream {
     The actual call chain is documented in the implementation of this function.
     */
 void grpc_chttp2_initiate_write(grpc_exec_ctx *exec_ctx,
-                                grpc_chttp2_transport *t, const char *reason);
+                                grpc_chttp2_transport *t,
+                                grpc_chttp2_initiate_write_reason reason);
 
 typedef struct {
   /** are we writing? */
@@ -851,10 +879,9 @@ void grpc_chttp2_add_ping_strike(grpc_exec_ctx *exec_ctx,
 
 /** add a ref to the stream and add it to the writable list;
     ref will be dropped in writing.c */
-void grpc_chttp2_become_writable(grpc_exec_ctx *exec_ctx,
-                                 grpc_chttp2_transport *t,
-                                 grpc_chttp2_stream *s,
-                                 bool also_initiate_write, const char *reason);
+void grpc_chttp2_mark_stream_writable(grpc_exec_ctx *exec_ctx,
+                                      grpc_chttp2_transport *t,
+                                      grpc_chttp2_stream *s);
 
 void grpc_chttp2_cancel_stream(grpc_exec_ctx *exec_ctx,
                                grpc_chttp2_transport *t, grpc_chttp2_stream *s,
diff --git a/src/core/ext/transport/chttp2/transport/writing.c b/src/core/ext/transport/chttp2/transport/writing.c
index 3fa38db4db..3ded801985 100644
--- a/src/core/ext/transport/chttp2/transport/writing.c
+++ b/src/core/ext/transport/chttp2/transport/writing.c
@@ -201,9 +201,8 @@ grpc_chttp2_begin_write_result grpc_chttp2_begin_write(
 
   if (t->flow_control.remote_window > 0) {
     while (grpc_chttp2_list_pop_stalled_by_transport(t, &s)) {
-      if (!t->closed && grpc_chttp2_list_add_writable_stream(t, s) &&
-          stream_ref_if_not_destroyed(&s->refcount->refs)) {
-        grpc_chttp2_initiate_write(exec_ctx, t, "transport.read_flow_control");
+      if (!t->closed && grpc_chttp2_list_add_writable_stream(t, s)) {
+        stream_ref_if_not_destroyed(&s->refcount->refs);
       }
     }
   }
diff --git a/src/core/lib/debug/stats_data.c b/src/core/lib/debug/stats_data.c
index 2c56765343..b3e1ee9b4e 100644
--- a/src/core/lib/debug/stats_data.c
+++ b/src/core/lib/debug/stats_data.c
@@ -50,6 +50,27 @@ const char *grpc_stats_counter_name[GRPC_STATS_COUNTER_COUNT] = {
     "http2_writes_offloaded",
     "http2_writes_continued",
     "http2_partial_writes",
+    "http2_initiate_write_due_to_initial_write",
+    "http2_initiate_write_due_to_start_new_stream",
+    "http2_initiate_write_due_to_send_message",
+    "http2_initiate_write_due_to_send_initial_metadata",
+    "http2_initiate_write_due_to_send_trailing_metadata",
+    "http2_initiate_write_due_to_retry_send_ping",
+    "http2_initiate_write_due_to_continue_pings",
+    "http2_initiate_write_due_to_goaway_sent",
+    "http2_initiate_write_due_to_rst_stream",
+    "http2_initiate_write_due_to_close_from_api",
+    "http2_initiate_write_due_to_stream_flow_control",
+    "http2_initiate_write_due_to_transport_flow_control",
+    "http2_initiate_write_due_to_send_settings",
+    "http2_initiate_write_due_to_bdp_estimator_ping",
+    "http2_initiate_write_due_to_flow_control_unstalled_by_setting",
+    "http2_initiate_write_due_to_flow_control_unstalled_by_update",
+    "http2_initiate_write_due_to_application_ping",
+    "http2_initiate_write_due_to_keepalive_ping",
+    "http2_initiate_write_due_to_transport_flow_control_unstalled",
+    "http2_initiate_write_due_to_ping_response",
+    "http2_initiate_write_due_to_force_rst_stream",
     "combiner_locks_initiated",
     "combiner_locks_scheduled_items",
     "combiner_locks_scheduled_final_items",
@@ -92,6 +113,30 @@ const char *grpc_stats_counter_doc[GRPC_STATS_COUNTER_COUNT] = {
     "written",
     "Number of HTTP2 writes that were made knowing there was still more data "
     "to be written (we cap maximum write size to syscall_write)",
+    "Number of HTTP2 writes initiated due to 'initial_write'",
+    "Number of HTTP2 writes initiated due to 'start_new_stream'",
+    "Number of HTTP2 writes initiated due to 'send_message'",
+    "Number of HTTP2 writes initiated due to 'send_initial_metadata'",
+    "Number of HTTP2 writes initiated due to 'send_trailing_metadata'",
+    "Number of HTTP2 writes initiated due to 'retry_send_ping'",
+    "Number of HTTP2 writes initiated due to 'continue_pings'",
+    "Number of HTTP2 writes initiated due to 'goaway_sent'",
+    "Number of HTTP2 writes initiated due to 'rst_stream'",
+    "Number of HTTP2 writes initiated due to 'close_from_api'",
+    "Number of HTTP2 writes initiated due to 'stream_flow_control'",
+    "Number of HTTP2 writes initiated due to 'transport_flow_control'",
+    "Number of HTTP2 writes initiated due to 'send_settings'",
+    "Number of HTTP2 writes initiated due to 'bdp_estimator_ping'",
+    "Number of HTTP2 writes initiated due to "
+    "'flow_control_unstalled_by_setting'",
+    "Number of HTTP2 writes initiated due to "
+    "'flow_control_unstalled_by_update'",
+    "Number of HTTP2 writes initiated due to 'application_ping'",
+    "Number of HTTP2 writes initiated due to 'keepalive_ping'",
+    "Number of HTTP2 writes initiated due to "
+    "'transport_flow_control_unstalled'",
+    "Number of HTTP2 writes initiated due to 'ping_response'",
+    "Number of HTTP2 writes initiated due to 'force_rst_stream'",
     "Number of combiner lock entries by process (first items queued to a "
     "combiner)",
     "Number of items scheduled against combiner locks",
diff --git a/src/core/lib/debug/stats_data.h b/src/core/lib/debug/stats_data.h
index e93db32c6a..c9871c4a56 100644
--- a/src/core/lib/debug/stats_data.h
+++ b/src/core/lib/debug/stats_data.h
@@ -52,6 +52,27 @@ typedef enum {
   GRPC_STATS_COUNTER_HTTP2_WRITES_OFFLOADED,
   GRPC_STATS_COUNTER_HTTP2_WRITES_CONTINUED,
   GRPC_STATS_COUNTER_HTTP2_PARTIAL_WRITES,
+  GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_INITIAL_WRITE,
+  GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_START_NEW_STREAM,
+  GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_SEND_MESSAGE,
+  GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_SEND_INITIAL_METADATA,
+  GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_SEND_TRAILING_METADATA,
+  GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_RETRY_SEND_PING,
+  GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_CONTINUE_PINGS,
+  GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_GOAWAY_SENT,
+  GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_RST_STREAM,
+  GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_CLOSE_FROM_API,
+  GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_STREAM_FLOW_CONTROL,
+  GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_TRANSPORT_FLOW_CONTROL,
+  GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_SEND_SETTINGS,
+  GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_BDP_ESTIMATOR_PING,
+  GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_FLOW_CONTROL_UNSTALLED_BY_SETTING,
+  GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_FLOW_CONTROL_UNSTALLED_BY_UPDATE,
+  GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_APPLICATION_PING,
+  GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_KEEPALIVE_PING,
+  GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_TRANSPORT_FLOW_CONTROL_UNSTALLED,
+  GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_PING_RESPONSE,
+  GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_FORCE_RST_STREAM,
   GRPC_STATS_COUNTER_COMBINER_LOCKS_INITIATED,
   GRPC_STATS_COUNTER_COMBINER_LOCKS_SCHEDULED_ITEMS,
   GRPC_STATS_COUNTER_COMBINER_LOCKS_SCHEDULED_FINAL_ITEMS,
@@ -169,6 +190,95 @@ typedef enum {
   GRPC_STATS_INC_COUNTER((exec_ctx), GRPC_STATS_COUNTER_HTTP2_WRITES_CONTINUED)
 #define GRPC_STATS_INC_HTTP2_PARTIAL_WRITES(exec_ctx) \
   GRPC_STATS_INC_COUNTER((exec_ctx), GRPC_STATS_COUNTER_HTTP2_PARTIAL_WRITES)
+#define GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_INITIAL_WRITE(exec_ctx) \
+  GRPC_STATS_INC_COUNTER(                                                  \
+      (exec_ctx),                                                          \
+      GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_INITIAL_WRITE)
+#define GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_START_NEW_STREAM(exec_ctx) \
+  GRPC_STATS_INC_COUNTER(                                                     \
+      (exec_ctx),                                                             \
+      GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_START_NEW_STREAM)
+#define GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_SEND_MESSAGE(exec_ctx) \
+  GRPC_STATS_INC_COUNTER(                                                 \
+      (exec_ctx), GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_SEND_MESSAGE)
+#define GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_SEND_INITIAL_METADATA( \
+    exec_ctx)                                                             \
+  GRPC_STATS_INC_COUNTER(                                                 \
+      (exec_ctx),                                                         \
+      GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_SEND_INITIAL_METADATA)
+#define GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_SEND_TRAILING_METADATA( \
+    exec_ctx)                                                              \
+  GRPC_STATS_INC_COUNTER(                                                  \
+      (exec_ctx),                                                          \
+      GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_SEND_TRAILING_METADATA)
+#define GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_RETRY_SEND_PING(exec_ctx) \
+  GRPC_STATS_INC_COUNTER(                                                    \
+      (exec_ctx),                                                            \
+      GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_RETRY_SEND_PING)
+#define GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_CONTINUE_PINGS(exec_ctx) \
+  GRPC_STATS_INC_COUNTER(                                                   \
+      (exec_ctx),                                                           \
+      GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_CONTINUE_PINGS)
+#define GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_GOAWAY_SENT(exec_ctx) \
+  GRPC_STATS_INC_COUNTER(                                                \
+      (exec_ctx), GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_GOAWAY_SENT)
+#define GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_RST_STREAM(exec_ctx) \
+  GRPC_STATS_INC_COUNTER(                                               \
+      (exec_ctx), GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_RST_STREAM)
+#define GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_CLOSE_FROM_API(exec_ctx) \
+  GRPC_STATS_INC_COUNTER(                                                   \
+      (exec_ctx),                                                           \
+      GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_CLOSE_FROM_API)
+#define GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_STREAM_FLOW_CONTROL( \
+    exec_ctx)                                                           \
+  GRPC_STATS_INC_COUNTER(                                               \
+      (exec_ctx),                                                       \
+      GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_STREAM_FLOW_CONTROL)
+#define GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_TRANSPORT_FLOW_CONTROL( \
+    exec_ctx)                                                              \
+  GRPC_STATS_INC_COUNTER(                                                  \
+      (exec_ctx),                                                          \
+      GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_TRANSPORT_FLOW_CONTROL)
+#define GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_SEND_SETTINGS(exec_ctx) \
+  GRPC_STATS_INC_COUNTER(                                                  \
+      (exec_ctx),                                                          \
+      GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_SEND_SETTINGS)
+#define GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_BDP_ESTIMATOR_PING( \
+    exec_ctx)                                                          \
+  GRPC_STATS_INC_COUNTER(                                              \
+      (exec_ctx),                                                      \
+      GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_BDP_ESTIMATOR_PING)
+#define GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_FLOW_CONTROL_UNSTALLED_BY_SETTING( \
+    exec_ctx)                                                                         \
+  GRPC_STATS_INC_COUNTER(                                                             \
+      (exec_ctx),                                                                     \
+      GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_FLOW_CONTROL_UNSTALLED_BY_SETTING)
+#define GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_FLOW_CONTROL_UNSTALLED_BY_UPDATE( \
+    exec_ctx)                                                                        \
+  GRPC_STATS_INC_COUNTER(                                                            \
+      (exec_ctx),                                                                    \
+      GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_FLOW_CONTROL_UNSTALLED_BY_UPDATE)
+#define GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_APPLICATION_PING(exec_ctx) \
+  GRPC_STATS_INC_COUNTER(                                                     \
+      (exec_ctx),                                                             \
+      GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_APPLICATION_PING)
+#define GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_KEEPALIVE_PING(exec_ctx) \
+  GRPC_STATS_INC_COUNTER(                                                   \
+      (exec_ctx),                                                           \
+      GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_KEEPALIVE_PING)
+#define GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_TRANSPORT_FLOW_CONTROL_UNSTALLED( \
+    exec_ctx)                                                                        \
+  GRPC_STATS_INC_COUNTER(                                                            \
+      (exec_ctx),                                                                    \
+      GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_TRANSPORT_FLOW_CONTROL_UNSTALLED)
+#define GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_PING_RESPONSE(exec_ctx) \
+  GRPC_STATS_INC_COUNTER(                                                  \
+      (exec_ctx),                                                          \
+      GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_PING_RESPONSE)
+#define GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_FORCE_RST_STREAM(exec_ctx) \
+  GRPC_STATS_INC_COUNTER(                                                     \
+      (exec_ctx),                                                             \
+      GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_FORCE_RST_STREAM)
 #define GRPC_STATS_INC_COMBINER_LOCKS_INITIATED(exec_ctx) \
   GRPC_STATS_INC_COUNTER((exec_ctx),                      \
                          GRPC_STATS_COUNTER_COMBINER_LOCKS_INITIATED)
diff --git a/src/core/lib/debug/stats_data.yaml b/src/core/lib/debug/stats_data.yaml
index 37dff9c5f4..84727fe6c4 100644
--- a/src/core/lib/debug/stats_data.yaml
+++ b/src/core/lib/debug/stats_data.yaml
@@ -117,6 +117,48 @@
 - counter: http2_partial_writes
   doc: Number of HTTP2 writes that were made knowing there was still more data
        to be written (we cap maximum write size to syscall_write)
+- counter: http2_initiate_write_due_to_initial_write
+  doc: Number of HTTP2 writes initiated due to 'initial_write'
+- counter: http2_initiate_write_due_to_start_new_stream
+  doc: Number of HTTP2 writes initiated due to 'start_new_stream'
+- counter: http2_initiate_write_due_to_send_message
+  doc: Number of HTTP2 writes initiated due to 'send_message'
+- counter: http2_initiate_write_due_to_send_initial_metadata
+  doc: Number of HTTP2 writes initiated due to 'send_initial_metadata'
+- counter: http2_initiate_write_due_to_send_trailing_metadata
+  doc: Number of HTTP2 writes initiated due to 'send_trailing_metadata'
+- counter: http2_initiate_write_due_to_retry_send_ping
+  doc: Number of HTTP2 writes initiated due to 'retry_send_ping'
+- counter: http2_initiate_write_due_to_continue_pings
+  doc: Number of HTTP2 writes initiated due to 'continue_pings'
+- counter: http2_initiate_write_due_to_goaway_sent
+  doc: Number of HTTP2 writes initiated due to 'goaway_sent'
+- counter: http2_initiate_write_due_to_rst_stream
+  doc: Number of HTTP2 writes initiated due to 'rst_stream'
+- counter: http2_initiate_write_due_to_close_from_api
+  doc: Number of HTTP2 writes initiated due to 'close_from_api'
+- counter: http2_initiate_write_due_to_stream_flow_control
+  doc: Number of HTTP2 writes initiated due to 'stream_flow_control'
+- counter: http2_initiate_write_due_to_transport_flow_control
+  doc: Number of HTTP2 writes initiated due to 'transport_flow_control'
+- counter: http2_initiate_write_due_to_send_settings
+  doc: Number of HTTP2 writes initiated due to 'send_settings'
+- counter: http2_initiate_write_due_to_bdp_estimator_ping
+  doc: Number of HTTP2 writes initiated due to 'bdp_estimator_ping'
+- counter: http2_initiate_write_due_to_flow_control_unstalled_by_setting
+  doc: Number of HTTP2 writes initiated due to 'flow_control_unstalled_by_setting'
+- counter: http2_initiate_write_due_to_flow_control_unstalled_by_update
+  doc: Number of HTTP2 writes initiated due to 'flow_control_unstalled_by_update'
+- counter: http2_initiate_write_due_to_application_ping
+  doc: Number of HTTP2 writes initiated due to 'application_ping'
+- counter: http2_initiate_write_due_to_keepalive_ping
+  doc: Number of HTTP2 writes initiated due to 'keepalive_ping'
+- counter: http2_initiate_write_due_to_transport_flow_control_unstalled
+  doc: Number of HTTP2 writes initiated due to 'transport_flow_control_unstalled'
+- counter: http2_initiate_write_due_to_ping_response
+  doc: Number of HTTP2 writes initiated due to 'ping_response'
+- counter: http2_initiate_write_due_to_force_rst_stream
+  doc: Number of HTTP2 writes initiated due to 'force_rst_stream'
 # combiner locks
 - counter: combiner_locks_initiated
   doc: Number of combiner lock entries by process
diff --git a/src/core/lib/debug/stats_data_bq_schema.sql b/src/core/lib/debug/stats_data_bq_schema.sql
index 5354769291..d21afbbfe4 100644
--- a/src/core/lib/debug/stats_data_bq_schema.sql
+++ b/src/core/lib/debug/stats_data_bq_schema.sql
@@ -1,5 +1,9 @@
 client_calls_created_per_iteration:FLOAT,
 server_calls_created_per_iteration:FLOAT,
+cqs_created_per_iteration:FLOAT,
+client_channels_created_per_iteration:FLOAT,
+client_subchannels_created_per_iteration:FLOAT,
+server_channels_created_per_iteration:FLOAT,
 syscall_poll_per_iteration:FLOAT,
 syscall_wait_per_iteration:FLOAT,
 histogram_slow_lookups_per_iteration:FLOAT,
@@ -21,6 +25,27 @@ http2_writes_begun_per_iteration:FLOAT,
 http2_writes_offloaded_per_iteration:FLOAT,
 http2_writes_continued_per_iteration:FLOAT,
 http2_partial_writes_per_iteration:FLOAT,
+http2_initiate_write_due_to_initial_write_per_iteration:FLOAT,
+http2_initiate_write_due_to_start_new_stream_per_iteration:FLOAT,
+http2_initiate_write_due_to_send_message_per_iteration:FLOAT,
+http2_initiate_write_due_to_send_initial_metadata_per_iteration:FLOAT,
+http2_initiate_write_due_to_send_trailing_metadata_per_iteration:FLOAT,
+http2_initiate_write_due_to_retry_send_ping_per_iteration:FLOAT,
+http2_initiate_write_due_to_continue_pings_per_iteration:FLOAT,
+http2_initiate_write_due_to_goaway_sent_per_iteration:FLOAT,
+http2_initiate_write_due_to_rst_stream_per_iteration:FLOAT,
+http2_initiate_write_due_to_close_from_api_per_iteration:FLOAT,
+http2_initiate_write_due_to_stream_flow_control_per_iteration:FLOAT,
+http2_initiate_write_due_to_transport_flow_control_per_iteration:FLOAT,
+http2_initiate_write_due_to_send_settings_per_iteration:FLOAT,
+http2_initiate_write_due_to_bdp_estimator_ping_per_iteration:FLOAT,
+http2_initiate_write_due_to_flow_control_unstalled_by_setting_per_iteration:FLOAT,
+http2_initiate_write_due_to_flow_control_unstalled_by_update_per_iteration:FLOAT,
+http2_initiate_write_due_to_application_ping_per_iteration:FLOAT,
+http2_initiate_write_due_to_keepalive_ping_per_iteration:FLOAT,
+http2_initiate_write_due_to_transport_flow_control_unstalled_per_iteration:FLOAT,
+http2_initiate_write_due_to_ping_response_per_iteration:FLOAT,
+http2_initiate_write_due_to_force_rst_stream_per_iteration:FLOAT,
 combiner_locks_initiated_per_iteration:FLOAT,
 combiner_locks_scheduled_items_per_iteration:FLOAT,
 combiner_locks_scheduled_final_items_per_iteration:FLOAT,
diff --git a/src/core/lib/iomgr/resource_quota.c b/src/core/lib/iomgr/resource_quota.c
index 4d69986fbc..4895e0d1c9 100644
--- a/src/core/lib/iomgr/resource_quota.c
+++ b/src/core/lib/iomgr/resource_quota.c
@@ -22,7 +22,6 @@
 #include <stdint.h>
 #include <string.h>
 
-#include <grpc/slice_buffer.h>
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
 #include <grpc/support/string_util.h>