Merge branch 'master' into epollex-ownerfd-fix

24 files changed, 644 insertions, 205 deletions

diff --git a/src/core/ext/filters/client_channel/client_channel.cc b/src/core/ext/filters/client_channel/client_channel.cc
index 34ea97e23e..520431e63b 100644
--- a/src/core/ext/filters/client_channel/client_channel.cc
+++ b/src/core/ext/filters/client_channel/client_channel.cc
@@ -794,6 +794,15 @@ typedef struct {
   // The batch to use in the subchannel call.
   // Its payload field points to subchannel_call_retry_state.batch_payload.
   grpc_transport_stream_op_batch batch;
+  // For intercepting on_complete.
+  grpc_closure on_complete;
+} subchannel_batch_data;
+
+// Retry state associated with a subchannel call.
+// Stored in the parent_data of the subchannel call object.
+typedef struct {
+  // subchannel_batch_data.batch.payload points to this.
+  grpc_transport_stream_op_batch_payload batch_payload;
   // For send_initial_metadata.
   // Note that we need to make a copy of the initial metadata for each
   // subchannel call instead of just referring to the copy in call_data,
@@ -818,15 +827,6 @@ typedef struct {
   grpc_metadata_batch recv_trailing_metadata;
   grpc_transport_stream_stats collect_stats;
   grpc_closure recv_trailing_metadata_ready;
-  // For intercepting on_complete.
-  grpc_closure on_complete;
-} subchannel_batch_data;
-
-// Retry state associated with a subchannel call.
-// Stored in the parent_data of the subchannel call object.
-typedef struct {
-  // subchannel_batch_data.batch.payload points to this.
-  grpc_transport_stream_op_batch_payload batch_payload;
   // These fields indicate which ops have been started and completed on
   // this subchannel call.
   size_t started_send_message_count;
@@ -1524,17 +1524,21 @@ static subchannel_batch_data* batch_data_create(grpc_call_element* elem,
 
 static void batch_data_unref(subchannel_batch_data* batch_data) {
   if (gpr_unref(&batch_data->refs)) {
-    if (batch_data->send_initial_metadata_storage != nullptr) {
-      grpc_metadata_batch_destroy(&batch_data->send_initial_metadata);
+    subchannel_call_retry_state* retry_state =
+        static_cast<subchannel_call_retry_state*>(
+            grpc_connected_subchannel_call_get_parent_data(
+                batch_data->subchannel_call));
+    if (batch_data->batch.send_initial_metadata) {
+      grpc_metadata_batch_destroy(&retry_state->send_initial_metadata);
     }
-    if (batch_data->send_trailing_metadata_storage != nullptr) {
-      grpc_metadata_batch_destroy(&batch_data->send_trailing_metadata);
+    if (batch_data->batch.send_trailing_metadata) {
+      grpc_metadata_batch_destroy(&retry_state->send_trailing_metadata);
     }
     if (batch_data->batch.recv_initial_metadata) {
-      grpc_metadata_batch_destroy(&batch_data->recv_initial_metadata);
+      grpc_metadata_batch_destroy(&retry_state->recv_initial_metadata);
     }
     if (batch_data->batch.recv_trailing_metadata) {
-      grpc_metadata_batch_destroy(&batch_data->recv_trailing_metadata);
+      grpc_metadata_batch_destroy(&retry_state->recv_trailing_metadata);
     }
     GRPC_SUBCHANNEL_CALL_UNREF(batch_data->subchannel_call, "batch_data_unref");
     call_data* calld = static_cast<call_data*>(batch_data->elem->call_data);
@@ -1560,8 +1564,12 @@ static void invoke_recv_initial_metadata_callback(void* arg,
       });
   GPR_ASSERT(pending != nullptr);
   // Return metadata.
+  subchannel_call_retry_state* retry_state =
+      static_cast<subchannel_call_retry_state*>(
+          grpc_connected_subchannel_call_get_parent_data(
+              batch_data->subchannel_call));
   grpc_metadata_batch_move(
-      &batch_data->recv_initial_metadata,
+      &retry_state->recv_initial_metadata,
       pending->batch->payload->recv_initial_metadata.recv_initial_metadata);
   // Update bookkeeping.
   // Note: Need to do this before invoking the callback, since invoking
@@ -1606,7 +1614,7 @@ static void recv_initial_metadata_ready(void* arg, grpc_error* error) {
   // the recv_trailing_metadata_ready callback, then defer propagating this
   // callback back to the surface.  We can evaluate whether to retry when
   // recv_trailing_metadata comes back.
-  if (GPR_UNLIKELY((batch_data->trailing_metadata_available ||
+  if (GPR_UNLIKELY((retry_state->trailing_metadata_available ||
                     error != GRPC_ERROR_NONE) &&
                    !retry_state->completed_recv_trailing_metadata)) {
     if (grpc_client_channel_trace.enabled()) {
@@ -1651,8 +1659,12 @@ static void invoke_recv_message_callback(void* arg, grpc_error* error) {
       });
   GPR_ASSERT(pending != nullptr);
   // Return payload.
+  subchannel_call_retry_state* retry_state =
+      static_cast<subchannel_call_retry_state*>(
+          grpc_connected_subchannel_call_get_parent_data(
+              batch_data->subchannel_call));
   *pending->batch->payload->recv_message.recv_message =
-      std::move(batch_data->recv_message);
+      std::move(retry_state->recv_message);
   // Update bookkeeping.
   // Note: Need to do this before invoking the callback, since invoking
   // the callback will result in yielding the call combiner.
@@ -1693,7 +1705,7 @@ static void recv_message_ready(void* arg, grpc_error* error) {
   // callback back to the surface.  We can evaluate whether to retry when
   // recv_trailing_metadata comes back.
   if (GPR_UNLIKELY(
-          (batch_data->recv_message == nullptr || error != GRPC_ERROR_NONE) &&
+          (retry_state->recv_message == nullptr || error != GRPC_ERROR_NONE) &&
           !retry_state->completed_recv_trailing_metadata)) {
     if (grpc_client_channel_trace.enabled()) {
       gpr_log(GPR_INFO,
@@ -1766,8 +1778,12 @@ static void add_closure_for_recv_trailing_metadata_ready(
     return;
   }
   // Return metadata.
+  subchannel_call_retry_state* retry_state =
+      static_cast<subchannel_call_retry_state*>(
+          grpc_connected_subchannel_call_get_parent_data(
+              batch_data->subchannel_call));
   grpc_metadata_batch_move(
-      &batch_data->recv_trailing_metadata,
+      &retry_state->recv_trailing_metadata,
       pending->batch->payload->recv_trailing_metadata.recv_trailing_metadata);
   // Add closure.
   closures->Add(pending->batch->payload->recv_trailing_metadata
@@ -1788,11 +1804,11 @@ static void add_closures_for_deferred_recv_callbacks(
     // Add closure for deferred recv_initial_metadata_ready.
     if (GPR_UNLIKELY(retry_state->recv_initial_metadata_ready_deferred_batch !=
                      nullptr)) {
-      GRPC_CLOSURE_INIT(&batch_data->recv_initial_metadata_ready,
+      GRPC_CLOSURE_INIT(&retry_state->recv_initial_metadata_ready,
                         invoke_recv_initial_metadata_callback,
                         retry_state->recv_initial_metadata_ready_deferred_batch,
                         grpc_schedule_on_exec_ctx);
-      closures->Add(&batch_data->recv_initial_metadata_ready,
+      closures->Add(&retry_state->recv_initial_metadata_ready,
                     retry_state->recv_initial_metadata_error,
                     "resuming recv_initial_metadata_ready");
       retry_state->recv_initial_metadata_ready_deferred_batch = nullptr;
@@ -1800,11 +1816,11 @@ static void add_closures_for_deferred_recv_callbacks(
     // Add closure for deferred recv_message_ready.
     if (GPR_UNLIKELY(retry_state->recv_message_ready_deferred_batch !=
                      nullptr)) {
-      GRPC_CLOSURE_INIT(&batch_data->recv_message_ready,
+      GRPC_CLOSURE_INIT(&retry_state->recv_message_ready,
                         invoke_recv_message_callback,
                         retry_state->recv_message_ready_deferred_batch,
                         grpc_schedule_on_exec_ctx);
-      closures->Add(&batch_data->recv_message_ready,
+      closures->Add(&retry_state->recv_message_ready,
                     retry_state->recv_message_error,
                     "resuming recv_message_ready");
       retry_state->recv_message_ready_deferred_batch = nullptr;
@@ -2120,28 +2136,28 @@ static void add_retriable_send_initial_metadata_op(
   //
   // If we've already completed one or more attempts, add the
   // grpc-retry-attempts header.
-  batch_data->send_initial_metadata_storage =
+  retry_state->send_initial_metadata_storage =
       static_cast<grpc_linked_mdelem*>(gpr_arena_alloc(
           calld->arena, sizeof(grpc_linked_mdelem) *
                             (calld->send_initial_metadata.list.count +
                              (calld->num_attempts_completed > 0))));
   grpc_metadata_batch_copy(&calld->send_initial_metadata,
-                           &batch_data->send_initial_metadata,
-                           batch_data->send_initial_metadata_storage);
-  if (GPR_UNLIKELY(batch_data->send_initial_metadata.idx.named
+                           &retry_state->send_initial_metadata,
+                           retry_state->send_initial_metadata_storage);
+  if (GPR_UNLIKELY(retry_state->send_initial_metadata.idx.named
                        .grpc_previous_rpc_attempts != nullptr)) {
-    grpc_metadata_batch_remove(
-        &batch_data->send_initial_metadata,
-        batch_data->send_initial_metadata.idx.named.grpc_previous_rpc_attempts);
+    grpc_metadata_batch_remove(&retry_state->send_initial_metadata,
+                               retry_state->send_initial_metadata.idx.named
+                                   .grpc_previous_rpc_attempts);
   }
   if (GPR_UNLIKELY(calld->num_attempts_completed > 0)) {
     grpc_mdelem retry_md = grpc_mdelem_from_slices(
         GRPC_MDSTR_GRPC_PREVIOUS_RPC_ATTEMPTS,
         *retry_count_strings[calld->num_attempts_completed - 1]);
     grpc_error* error = grpc_metadata_batch_add_tail(
-        &batch_data->send_initial_metadata,
-        &batch_data->send_initial_metadata_storage[calld->send_initial_metadata
-                                                       .list.count],
+        &retry_state->send_initial_metadata,
+        &retry_state->send_initial_metadata_storage[calld->send_initial_metadata
+                                                        .list.count],
         retry_md);
     if (GPR_UNLIKELY(error != GRPC_ERROR_NONE)) {
       gpr_log(GPR_ERROR, "error adding retry metadata: %s",
@@ -2152,7 +2168,7 @@ static void add_retriable_send_initial_metadata_op(
   retry_state->started_send_initial_metadata = true;
   batch_data->batch.send_initial_metadata = true;
   batch_data->batch.payload->send_initial_metadata.send_initial_metadata =
-      &batch_data->send_initial_metadata;
+      &retry_state->send_initial_metadata;
   batch_data->batch.payload->send_initial_metadata.send_initial_metadata_flags =
       calld->send_initial_metadata_flags;
   batch_data->batch.payload->send_initial_metadata.peer_string =
@@ -2173,10 +2189,10 @@ static void add_retriable_send_message_op(
   grpc_core::ByteStreamCache* cache =
       (*calld->send_messages)[retry_state->started_send_message_count];
   ++retry_state->started_send_message_count;
-  batch_data->send_message.Init(cache);
+  retry_state->send_message.Init(cache);
   batch_data->batch.send_message = true;
   batch_data->batch.payload->send_message.send_message.reset(
-      batch_data->send_message.get());
+      retry_state->send_message.get());
 }
 
 // Adds retriable send_trailing_metadata op to batch_data.
@@ -2186,17 +2202,17 @@ static void add_retriable_send_trailing_metadata_op(
   // We need to make a copy of the metadata batch for each attempt, since
   // the filters in the subchannel stack may modify this batch, and we don't
   // want those modifications to be passed forward to subsequent attempts.
-  batch_data->send_trailing_metadata_storage =
+  retry_state->send_trailing_metadata_storage =
       static_cast<grpc_linked_mdelem*>(gpr_arena_alloc(
           calld->arena, sizeof(grpc_linked_mdelem) *
                             calld->send_trailing_metadata.list.count));
   grpc_metadata_batch_copy(&calld->send_trailing_metadata,
-                           &batch_data->send_trailing_metadata,
-                           batch_data->send_trailing_metadata_storage);
+                           &retry_state->send_trailing_metadata,
+                           retry_state->send_trailing_metadata_storage);
   retry_state->started_send_trailing_metadata = true;
   batch_data->batch.send_trailing_metadata = true;
   batch_data->batch.payload->send_trailing_metadata.send_trailing_metadata =
-      &batch_data->send_trailing_metadata;
+      &retry_state->send_trailing_metadata;
 }
 
 // Adds retriable recv_initial_metadata op to batch_data.
@@ -2205,16 +2221,16 @@ static void add_retriable_recv_initial_metadata_op(
     subchannel_batch_data* batch_data) {
   retry_state->started_recv_initial_metadata = true;
   batch_data->batch.recv_initial_metadata = true;
-  grpc_metadata_batch_init(&batch_data->recv_initial_metadata);
+  grpc_metadata_batch_init(&retry_state->recv_initial_metadata);
   batch_data->batch.payload->recv_initial_metadata.recv_initial_metadata =
-      &batch_data->recv_initial_metadata;
+      &retry_state->recv_initial_metadata;
   batch_data->batch.payload->recv_initial_metadata.trailing_metadata_available =
-      &batch_data->trailing_metadata_available;
-  GRPC_CLOSURE_INIT(&batch_data->recv_initial_metadata_ready,
+      &retry_state->trailing_metadata_available;
+  GRPC_CLOSURE_INIT(&retry_state->recv_initial_metadata_ready,
                     recv_initial_metadata_ready, batch_data,
                     grpc_schedule_on_exec_ctx);
   batch_data->batch.payload->recv_initial_metadata.recv_initial_metadata_ready =
-      &batch_data->recv_initial_metadata_ready;
+      &retry_state->recv_initial_metadata_ready;
 }
 
 // Adds retriable recv_message op to batch_data.
@@ -2224,11 +2240,11 @@ static void add_retriable_recv_message_op(
   ++retry_state->started_recv_message_count;
   batch_data->batch.recv_message = true;
   batch_data->batch.payload->recv_message.recv_message =
-      &batch_data->recv_message;
-  GRPC_CLOSURE_INIT(&batch_data->recv_message_ready, recv_message_ready,
+      &retry_state->recv_message;
+  GRPC_CLOSURE_INIT(&retry_state->recv_message_ready, recv_message_ready,
                     batch_data, grpc_schedule_on_exec_ctx);
   batch_data->batch.payload->recv_message.recv_message_ready =
-      &batch_data->recv_message_ready;
+      &retry_state->recv_message_ready;
 }
 
 // Adds retriable recv_trailing_metadata op to batch_data.
@@ -2237,16 +2253,17 @@ static void add_retriable_recv_trailing_metadata_op(
     subchannel_batch_data* batch_data) {
   retry_state->started_recv_trailing_metadata = true;
   batch_data->batch.recv_trailing_metadata = true;
-  grpc_metadata_batch_init(&batch_data->recv_trailing_metadata);
+  grpc_metadata_batch_init(&retry_state->recv_trailing_metadata);
   batch_data->batch.payload->recv_trailing_metadata.recv_trailing_metadata =
-      &batch_data->recv_trailing_metadata;
+      &retry_state->recv_trailing_metadata;
   batch_data->batch.payload->recv_trailing_metadata.collect_stats =
-      &batch_data->collect_stats;
-  GRPC_CLOSURE_INIT(&batch_data->recv_trailing_metadata_ready,
+      &retry_state->collect_stats;
+  GRPC_CLOSURE_INIT(&retry_state->recv_trailing_metadata_ready,
                     recv_trailing_metadata_ready, batch_data,
                     grpc_schedule_on_exec_ctx);
   batch_data->batch.payload->recv_trailing_metadata
-      .recv_trailing_metadata_ready = &batch_data->recv_trailing_metadata_ready;
+      .recv_trailing_metadata_ready =
+      &retry_state->recv_trailing_metadata_ready;
 }
 
 // Helper function used to start a recv_trailing_metadata batch.  This
@@ -2400,11 +2417,9 @@ static void add_subchannel_batches_for_pending_batches(
         // started subchannel batch, since we'll propagate the
         // completion when it completes.
         if (retry_state->completed_recv_trailing_metadata) {
-          subchannel_batch_data* batch_data =
-              retry_state->recv_trailing_metadata_internal_batch;
           // Batches containing recv_trailing_metadata always succeed.
           closures->Add(
-              &batch_data->recv_trailing_metadata_ready, GRPC_ERROR_NONE,
+              &retry_state->recv_trailing_metadata_ready, GRPC_ERROR_NONE,
               "re-executing recv_trailing_metadata_ready to propagate "
               "internally triggered result");
         } else {
diff --git a/src/core/ext/transport/chttp2/transport/writing.cc b/src/core/ext/transport/chttp2/transport/writing.cc
index 34d5e6e218..8b73b01dea 100644
--- a/src/core/ext/transport/chttp2/transport/writing.cc
+++ b/src/core/ext/transport/chttp2/transport/writing.cc
@@ -139,22 +139,27 @@ static bool update_list(grpc_chttp2_transport* t, grpc_chttp2_stream* s,
 
 static void report_stall(grpc_chttp2_transport* t, grpc_chttp2_stream* s,
                          const char* staller) {
-  gpr_log(
-      GPR_DEBUG,
-      "%s:%p stream %d stalled by %s [fc:pending=%" PRIdPTR
-      ":pending-compressed=%" PRIdPTR ":flowed=%" PRId64
-      ":peer_initwin=%d:t_win=%" PRId64 ":s_win=%d:s_delta=%" PRId64 "]",
-      t->peer_string, t, s->id, staller, s->flow_controlled_buffer.length,
-      s->compressed_data_buffer.length, s->flow_controlled_bytes_flowed,
-      t->settings[GRPC_ACKED_SETTINGS]
-                 [GRPC_CHTTP2_SETTINGS_INITIAL_WINDOW_SIZE],
-      t->flow_control->remote_window(),
-      static_cast<uint32_t> GPR_MAX(
-          0,
-          s->flow_control->remote_window_delta() +
-              (int64_t)t->settings[GRPC_PEER_SETTINGS]
-                                  [GRPC_CHTTP2_SETTINGS_INITIAL_WINDOW_SIZE]),
-      s->flow_control->remote_window_delta());
+  if (grpc_flowctl_trace.enabled()) {
+    gpr_log(
+        GPR_DEBUG,
+        "%s:%p stream %d moved to stalled list by %s. This is FULLY expected "
+        "to happen in a healthy program that is not seeing flow control stalls."
+        " However, if you know that there are unwanted stalls, here is some "
+        "helpful data: [fc:pending=%" PRIdPTR ":pending-compressed=%" PRIdPTR
+        ":flowed=%" PRId64 ":peer_initwin=%d:t_win=%" PRId64
+        ":s_win=%d:s_delta=%" PRId64 "]",
+        t->peer_string, t, s->id, staller, s->flow_controlled_buffer.length,
+        s->compressed_data_buffer.length, s->flow_controlled_bytes_flowed,
+        t->settings[GRPC_ACKED_SETTINGS]
+                   [GRPC_CHTTP2_SETTINGS_INITIAL_WINDOW_SIZE],
+        t->flow_control->remote_window(),
+        static_cast<uint32_t> GPR_MAX(
+            0,
+            s->flow_control->remote_window_delta() +
+                (int64_t)t->settings[GRPC_PEER_SETTINGS]
+                                    [GRPC_CHTTP2_SETTINGS_INITIAL_WINDOW_SIZE]),
+        s->flow_control->remote_window_delta());
+  }
 }
 
 static bool stream_ref_if_not_destroyed(gpr_refcount* r) {
diff --git a/src/core/lib/channel/channel_trace.cc b/src/core/lib/channel/channel_trace.cc
index eb7214b355..0f655d8716 100644
--- a/src/core/lib/channel/channel_trace.cc
+++ b/src/core/lib/channel/channel_trace.cc
@@ -28,7 +28,6 @@
 #include <stdlib.h>
 #include <string.h>
 
-#include "src/core/lib/channel/channelz_registry.h"
 #include "src/core/lib/channel/status_util.h"
 #include "src/core/lib/gpr/string.h"
 #include "src/core/lib/gpr/useful.h"
@@ -40,16 +39,17 @@
 #include "src/core/lib/transport/error_utils.h"
 
 namespace grpc_core {
+namespace channelz {
 
 ChannelTrace::TraceEvent::TraceEvent(
     Severity severity, grpc_slice data,
-    RefCountedPtr<ChannelTrace> referenced_tracer, ReferencedType type)
+    RefCountedPtr<ChannelNode> referenced_channel, ReferencedType type)
     : severity_(severity),
       data_(data),
       timestamp_(grpc_millis_to_timespec(grpc_core::ExecCtx::Get()->Now(),
                                          GPR_CLOCK_REALTIME)),
       next_(nullptr),
-      referenced_tracer_(std::move(referenced_tracer)),
+      referenced_channel_(std::move(referenced_channel)),
       referenced_type_(type) {}
 
 ChannelTrace::TraceEvent::TraceEvent(Severity severity, grpc_slice data)
@@ -62,15 +62,13 @@ ChannelTrace::TraceEvent::TraceEvent(Severity severity, grpc_slice data)
 ChannelTrace::TraceEvent::~TraceEvent() { grpc_slice_unref_internal(data_); }
 
 ChannelTrace::ChannelTrace(size_t max_events)
-    : channel_uuid_(-1),
-      num_events_logged_(0),
+    : num_events_logged_(0),
       list_size_(0),
       max_list_size_(max_events),
       head_trace_(nullptr),
       tail_trace_(nullptr) {
   if (max_list_size_ == 0) return;  // tracing is disabled if max_events == 0
   gpr_mu_init(&tracer_mu_);
-  channel_uuid_ = ChannelzRegistry::Register(this);
   time_created_ = grpc_millis_to_timespec(grpc_core::ExecCtx::Get()->Now(),
                                           GPR_CLOCK_REALTIME);
 }
@@ -83,12 +81,9 @@ ChannelTrace::~ChannelTrace() {
     it = it->next();
     Delete<TraceEvent>(to_free);
   }
-  ChannelzRegistry::Unregister(channel_uuid_);
   gpr_mu_destroy(&tracer_mu_);
 }
 
-intptr_t ChannelTrace::GetUuid() const { return channel_uuid_; }
-
 void ChannelTrace::AddTraceEventHelper(TraceEvent* new_trace_event) {
   ++num_events_logged_;
   // first event case
@@ -117,20 +112,21 @@ void ChannelTrace::AddTraceEvent(Severity severity, grpc_slice data) {
 
 void ChannelTrace::AddTraceEventReferencingChannel(
     Severity severity, grpc_slice data,
-    RefCountedPtr<ChannelTrace> referenced_tracer) {
+    RefCountedPtr<ChannelNode> referenced_channel) {
   if (max_list_size_ == 0) return;  // tracing is disabled if max_events == 0
   // create and fill up the new event
-  AddTraceEventHelper(
-      New<TraceEvent>(severity, data, std::move(referenced_tracer), Channel));
+  AddTraceEventHelper(New<TraceEvent>(
+      severity, data, std::move(referenced_channel), ReferencedType::Channel));
 }
 
 void ChannelTrace::AddTraceEventReferencingSubchannel(
     Severity severity, grpc_slice data,
-    RefCountedPtr<ChannelTrace> referenced_tracer) {
+    RefCountedPtr<ChannelNode> referenced_subchannel) {
   if (max_list_size_ == 0) return;  // tracing is disabled if max_events == 0
   // create and fill up the new event
-  AddTraceEventHelper(New<TraceEvent>(
-      severity, data, std::move(referenced_tracer), Subchannel));
+  AddTraceEventHelper(New<TraceEvent>(severity, data,
+                                      std::move(referenced_subchannel),
+                                      ReferencedType::Subchannel));
 }
 
 namespace {
@@ -193,22 +189,24 @@ void ChannelTrace::TraceEvent::RenderTraceEvent(grpc_json* json) const {
   json_iterator =
       grpc_json_create_child(json_iterator, json, "timestamp",
                              fmt_time(timestamp_), GRPC_JSON_STRING, true);
-  if (referenced_tracer_ != nullptr) {
+  if (referenced_channel_ != nullptr) {
     char* uuid_str;
-    gpr_asprintf(&uuid_str, "%" PRIdPTR, referenced_tracer_->channel_uuid_);
+    gpr_asprintf(&uuid_str, "%" PRIdPTR, referenced_channel_->channel_uuid());
     grpc_json* child_ref = grpc_json_create_child(
         json_iterator, json,
-        (referenced_type_ == Channel) ? "channelRef" : "subchannelRef", nullptr,
-        GRPC_JSON_OBJECT, false);
+        (referenced_type_ == ReferencedType::Channel) ? "channelRef"
+                                                      : "subchannelRef",
+        nullptr, GRPC_JSON_OBJECT, false);
     json_iterator = grpc_json_create_child(
         nullptr, child_ref,
-        (referenced_type_ == Channel) ? "channelId" : "subchannelId", uuid_str,
-        GRPC_JSON_STRING, true);
+        (referenced_type_ == ReferencedType::Channel) ? "channelId"
+                                                      : "subchannelId",
+        uuid_str, GRPC_JSON_STRING, true);
     json_iterator = child_ref;
   }
 }
 
-char* ChannelTrace::RenderTrace() const {
+grpc_json* ChannelTrace::RenderJSON() const {
   if (!max_list_size_)
     return nullptr;  // tracing is disabled if max_events == 0
   grpc_json* json = grpc_json_create(GRPC_JSON_OBJECT);
@@ -219,7 +217,7 @@ char* ChannelTrace::RenderTrace() const {
       grpc_json_create_child(json_iterator, json, "numEventsLogged",
                              num_events_logged_str, GRPC_JSON_STRING, true);
   json_iterator =
-      grpc_json_create_child(json_iterator, json, "creationTime",
+      grpc_json_create_child(json_iterator, json, "creationTimestamp",
                              fmt_time(time_created_), GRPC_JSON_STRING, true);
   grpc_json* events = grpc_json_create_child(json_iterator, json, "events",
                                              nullptr, GRPC_JSON_ARRAY, false);
@@ -231,9 +229,8 @@ char* ChannelTrace::RenderTrace() const {
     it->RenderTraceEvent(json_iterator);
     it = it->next();
   }
-  char* json_str = grpc_json_dump_to_string(json, 0);
-  grpc_json_destroy(json);
-  return json_str;
+  return json;
 }
 
+}  // namespace channelz
 }  // namespace grpc_core
diff --git a/src/core/lib/channel/channel_trace.h b/src/core/lib/channel/channel_trace.h
index 1df1e585f2..0dd162a777 100644
--- a/src/core/lib/channel/channel_trace.h
+++ b/src/core/lib/channel/channel_trace.h
@@ -28,18 +28,18 @@
 #include "src/core/lib/json/json.h"
 
 namespace grpc_core {
+namespace channelz {
+
+class ChannelNode;
 
 // Object used to hold live data for a channel. This data is exposed via the
 // channelz service:
 // https://github.com/grpc/proposal/blob/master/A14-channelz.md
-class ChannelTrace : public RefCounted<ChannelTrace> {
+class ChannelTrace {
  public:
   ChannelTrace(size_t max_events);
   ~ChannelTrace();
 
-  // returns the tracer's uuid
-  intptr_t GetUuid() const;
-
   enum Severity {
     Unset = 0,  // never to be used
     Info,       // we start at 1 to avoid using proto default values
@@ -59,34 +59,30 @@ class ChannelTrace : public RefCounted<ChannelTrace> {
   // created a new subchannel, then it would record that with a TraceEvent
   // referencing the new subchannel.
   //
-  // TODO(ncteisen): Once channelz is implemented, the events should reference
-  // the overall channelz object, not just the ChannelTrace object.
   // TODO(ncteisen): as this call is used more and more throughout the gRPC
   // stack, determine if it makes more sense to accept a char* instead of a
   // slice.
   void AddTraceEventReferencingChannel(
       Severity severity, grpc_slice data,
-      RefCountedPtr<ChannelTrace> referenced_tracer);
+      RefCountedPtr<ChannelNode> referenced_channel);
   void AddTraceEventReferencingSubchannel(
       Severity severity, grpc_slice data,
-      RefCountedPtr<ChannelTrace> referenced_tracer);
+      RefCountedPtr<ChannelNode> referenced_subchannel);
 
-  // Returns the tracing data rendered as a grpc json string.
-  // The string is owned by the caller and must be freed.
-  char* RenderTrace() const;
+  // Creates and returns the raw grpc_json object, so a parent channelz
+  // object may incorporate the json before rendering.
+  grpc_json* RenderJSON() const;
 
  private:
   // Types of objects that can be references by trace events.
-  enum ReferencedType { Channel, Subchannel };
+  enum class ReferencedType { Channel, Subchannel };
   // Private class to encapsulate all the data and bookkeeping needed for a
   // a trace event.
   class TraceEvent {
    public:
     // Constructor for a TraceEvent that references a different channel.
-    // TODO(ncteisen): once channelz is implemented, this should reference the
-    // overall channelz object, not just the ChannelTrace object
     TraceEvent(Severity severity, grpc_slice data,
-               RefCountedPtr<ChannelTrace> referenced_tracer,
+               RefCountedPtr<ChannelNode> referenced_channel,
                ReferencedType type);
 
     // Constructor for a TraceEvent that does not reverence a different
@@ -109,7 +105,7 @@ class ChannelTrace : public RefCounted<ChannelTrace> {
     gpr_timespec timestamp_;
     TraceEvent* next_;
     // the tracer object for the (sub)channel that this trace event refers to.
-    RefCountedPtr<ChannelTrace> referenced_tracer_;
+    RefCountedPtr<ChannelNode> referenced_channel_;
     // the type that the referenced tracer points to. Unused if this trace
     // does not point to any channel or subchannel
     ReferencedType referenced_type_;
@@ -119,7 +115,6 @@ class ChannelTrace : public RefCounted<ChannelTrace> {
   void AddTraceEventHelper(TraceEvent* new_trace_event);
 
   gpr_mu tracer_mu_;
-  intptr_t channel_uuid_;
   uint64_t num_events_logged_;
   size_t list_size_;
   size_t max_list_size_;
@@ -128,6 +123,7 @@ class ChannelTrace : public RefCounted<ChannelTrace> {
   gpr_timespec time_created_;
 };
 
+}  // namespace channelz
 }  // namespace grpc_core
 
 #endif /* GRPC_CORE_LIB_CHANNEL_CHANNEL_TRACE_H */
diff --git a/src/core/lib/channel/channelz.cc b/src/core/lib/channel/channelz.cc
new file mode 100644
index 0000000000..3550fc0551
--- /dev/null
+++ b/src/core/lib/channel/channelz.cc
@@ -0,0 +1,185 @@
+/*
+ *
+ * Copyright 2017 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+#include <grpc/impl/codegen/port_platform.h>
+
+#include "src/core/lib/channel/channelz.h"
+
+#include <grpc/grpc.h>
+#include <grpc/support/alloc.h>
+#include <grpc/support/log.h>
+#include <grpc/support/string_util.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "src/core/lib/channel/channelz_registry.h"
+#include "src/core/lib/channel/status_util.h"
+#include "src/core/lib/gpr/string.h"
+#include "src/core/lib/gpr/useful.h"
+#include "src/core/lib/gprpp/memory.h"
+#include "src/core/lib/iomgr/error.h"
+#include "src/core/lib/slice/slice_internal.h"
+#include "src/core/lib/surface/channel.h"
+#include "src/core/lib/transport/connectivity_state.h"
+#include "src/core/lib/transport/error_utils.h"
+
+namespace grpc_core {
+namespace channelz {
+
+namespace {
+
+// TODO(ncteisen): move this function to a common helper location.
+//
+// returns an allocated string that represents tm according to RFC-3339, and,
+// more specifically, follows:
+// https://developers.google.com/protocol-buffers/docs/proto3#json
+//
+// "Uses RFC 3339, where generated output will always be Z-normalized and uses
+// 0, 3, 6 or 9 fractional digits."
+char* fmt_time(gpr_timespec tm) {
+  char time_buffer[35];
+  char ns_buffer[11];  // '.' + 9 digits of precision
+  struct tm* tm_info = localtime((const time_t*)&tm.tv_sec);
+  strftime(time_buffer, sizeof(time_buffer), "%Y-%m-%dT%H:%M:%S", tm_info);
+  snprintf(ns_buffer, 11, ".%09d", tm.tv_nsec);
+  // This loop trims off trailing zeros by inserting a null character that the
+  // right point. We iterate in chunks of three because we want 0, 3, 6, or 9
+  // fractional digits.
+  for (int i = 7; i >= 1; i -= 3) {
+    if (ns_buffer[i] == '0' && ns_buffer[i + 1] == '0' &&
+        ns_buffer[i + 2] == '0') {
+      ns_buffer[i] = '\0';
+      // Edge case in which all fractional digits were 0.
+      if (i == 1) {
+        ns_buffer[0] = '\0';
+      }
+    } else {
+      break;
+    }
+  }
+  char* full_time_str;
+  gpr_asprintf(&full_time_str, "%s%sZ", time_buffer, ns_buffer);
+  return full_time_str;
+}
+
+// TODO(ncteisen); move this to json library
+grpc_json* add_num_str(grpc_json* parent, grpc_json* it, const char* name,
+                       int64_t num) {
+  char* num_str;
+  gpr_asprintf(&num_str, "%" PRId64, num);
+  return grpc_json_create_child(it, parent, name, num_str, GRPC_JSON_STRING,
+                                true);
+}
+
+}  // namespace
+
+ChannelNode::ChannelNode(grpc_channel* channel, size_t channel_tracer_max_nodes)
+    : channel_(channel), target_(nullptr), channel_uuid_(-1) {
+  trace_.Init(channel_tracer_max_nodes);
+  target_ = UniquePtr<char>(grpc_channel_get_target(channel_));
+  channel_uuid_ = ChannelzRegistry::Register(this);
+  gpr_atm_no_barrier_store(&last_call_started_millis_,
+                           (gpr_atm)ExecCtx::Get()->Now());
+}
+
+ChannelNode::~ChannelNode() {
+  trace_.Destroy();
+  ChannelzRegistry::Unregister(channel_uuid_);
+}
+
+void ChannelNode::RecordCallStarted() {
+  gpr_atm_no_barrier_fetch_add(&calls_started_, (gpr_atm)1);
+  gpr_atm_no_barrier_store(&last_call_started_millis_,
+                           (gpr_atm)ExecCtx::Get()->Now());
+}
+
+grpc_connectivity_state ChannelNode::GetConnectivityState() {
+  if (channel_ == nullptr) {
+    return GRPC_CHANNEL_SHUTDOWN;
+  } else {
+    return grpc_channel_check_connectivity_state(channel_, false);
+  }
+}
+
+char* ChannelNode::RenderJSON() {
+  // We need to track these three json objects to build our object
+  grpc_json* top_level_json = grpc_json_create(GRPC_JSON_OBJECT);
+  grpc_json* json = top_level_json;
+  grpc_json* json_iterator = nullptr;
+  // create and fill the ref child
+  json_iterator = grpc_json_create_child(json_iterator, json, "ref", nullptr,
+                                         GRPC_JSON_OBJECT, false);
+  json = json_iterator;
+  json_iterator = nullptr;
+  json_iterator = add_num_str(json, json_iterator, "channelId", channel_uuid_);
+  // reset json iterators to top level object
+  json = top_level_json;
+  json_iterator = nullptr;
+  // create and fill the data child.
+  grpc_json* data = grpc_json_create_child(json_iterator, json, "data", nullptr,
+                                           GRPC_JSON_OBJECT, false);
+  json = data;
+  json_iterator = nullptr;
+  // create and fill the connectivity state child.
+  grpc_connectivity_state connectivity_state = GetConnectivityState();
+  json_iterator = grpc_json_create_child(json_iterator, json, "state", nullptr,
+                                         GRPC_JSON_OBJECT, false);
+  json = json_iterator;
+  grpc_json_create_child(nullptr, json, "state",
+                         grpc_connectivity_state_name(connectivity_state),
+                         GRPC_JSON_STRING, false);
+  // reset the parent to be the data object.
+  json = data;
+  json_iterator = grpc_json_create_child(
+      json_iterator, json, "target", target_.get(), GRPC_JSON_STRING, false);
+  // fill in the channel trace if applicable
+  grpc_json* trace = trace_->RenderJSON();
+  if (trace != nullptr) {
+    // we manuall link up and fill the child since it was created for us in
+    // ChannelTrace::RenderJSON
+    json_iterator = grpc_json_link_child(json, trace, json_iterator);
+    trace->parent = json;
+    trace->value = nullptr;
+    trace->key = "trace";
+    trace->owns_value = false;
+  }
+  // reset the parent to be the data object.
+  json = data;
+  json_iterator = nullptr;
+  // We use -1 as sentinel values since proto default value for integers is
+  // zero, and the confuses the parser into thinking the value weren't present
+  json_iterator =
+      add_num_str(json, json_iterator, "callsStarted", calls_started_);
+  json_iterator =
+      add_num_str(json, json_iterator, "callsSucceeded", calls_succeeded_);
+  json_iterator =
+      add_num_str(json, json_iterator, "callsFailed", calls_failed_);
+  gpr_timespec ts =
+      grpc_millis_to_timespec(last_call_started_millis_, GPR_CLOCK_REALTIME);
+  json_iterator =
+      grpc_json_create_child(json_iterator, json, "lastCallStartedTimestamp",
+                             fmt_time(ts), GRPC_JSON_STRING, true);
+  // render and return the over json object
+  char* json_str = grpc_json_dump_to_string(top_level_json, 0);
+  grpc_json_destroy(top_level_json);
+  return json_str;
+}
+
+}  // namespace channelz
+}  // namespace grpc_core
diff --git a/src/core/lib/channel/channelz.h b/src/core/lib/channel/channelz.h
new file mode 100644
index 0000000000..2aad1e82f4
--- /dev/null
+++ b/src/core/lib/channel/channelz.h
@@ -0,0 +1,85 @@
+/*
+ *
+ * Copyright 2018 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+#ifndef GRPC_CORE_LIB_CHANNEL_CHANNELZ_H
+#define GRPC_CORE_LIB_CHANNEL_CHANNELZ_H
+
+#include <grpc/impl/codegen/port_platform.h>
+
+#include <grpc/grpc.h>
+
+#include "src/core/lib/channel/channel_trace.h"
+#include "src/core/lib/gprpp/manual_constructor.h"
+#include "src/core/lib/gprpp/ref_counted.h"
+#include "src/core/lib/gprpp/ref_counted_ptr.h"
+#include "src/core/lib/iomgr/error.h"
+#include "src/core/lib/iomgr/exec_ctx.h"
+#include "src/core/lib/json/json.h"
+
+namespace grpc_core {
+namespace channelz {
+
+namespace testing {
+class ChannelNodePeer;
+}
+
+class ChannelNode : public RefCounted<ChannelNode> {
+ public:
+  ChannelNode(grpc_channel* channel, size_t channel_tracer_max_nodes);
+  ~ChannelNode();
+
+  void RecordCallStarted();
+  void RecordCallFailed() {
+    gpr_atm_no_barrier_fetch_add(&calls_failed_, (gpr_atm(1)));
+  }
+  void RecordCallSucceeded() {
+    gpr_atm_no_barrier_fetch_add(&calls_succeeded_, (gpr_atm(1)));
+  }
+
+  char* RenderJSON();
+
+  ChannelTrace* trace() { return trace_.get(); }
+
+  void set_channel_destroyed() {
+    GPR_ASSERT(channel_ != nullptr);
+    channel_ = nullptr;
+  }
+
+  intptr_t channel_uuid() { return channel_uuid_; }
+
+ private:
+  // testing peer friend.
+  friend class testing::ChannelNodePeer;
+
+  // helper for getting connectivity state.
+  grpc_connectivity_state GetConnectivityState();
+
+  grpc_channel* channel_ = nullptr;
+  UniquePtr<char> target_;
+  gpr_atm calls_started_ = 0;
+  gpr_atm calls_succeeded_ = 0;
+  gpr_atm calls_failed_ = 0;
+  gpr_atm last_call_started_millis_ = 0;
+  intptr_t channel_uuid_;
+  ManualConstructor<ChannelTrace> trace_;
+};
+
+}  // namespace channelz
+}  // namespace grpc_core
+
+#endif /* GRPC_CORE_LIB_CHANNEL_CHANNELZ_H */
diff --git a/src/core/lib/iomgr/socket_utils.h b/src/core/lib/iomgr/socket_utils.h
index cf1a7be648..14bb081e93 100644
--- a/src/core/lib/iomgr/socket_utils.h
+++ b/src/core/lib/iomgr/socket_utils.h
@@ -23,12 +23,21 @@
 
 #include <stddef.h>
 
+// TODO(juanlishen): The following functions might be simple enough to implement
+// ourselves, so that they don't cause any portability hassle.
+
 /* A wrapper for htons on POSIX and Windows */
 uint16_t grpc_htons(uint16_t hostshort);
 
 /* A wrapper for ntohs on POSIX and WINDOWS */
 uint16_t grpc_ntohs(uint16_t netshort);
 
+/* A wrapper for htonl on POSIX and Windows */
+uint32_t grpc_htonl(uint32_t hostlong);
+
+/* A wrapper for ntohl on POSIX and WINDOWS */
+uint32_t grpc_ntohl(uint32_t netlong);
+
 /* A wrapper for inet_pton on POSIX and WINDOWS */
 int grpc_inet_pton(int af, const char* src, void* dst);
 
diff --git a/src/core/lib/iomgr/socket_utils_common_posix.cc b/src/core/lib/iomgr/socket_utils_common_posix.cc
index caee652307..c4b991c94d 100644
--- a/src/core/lib/iomgr/socket_utils_common_posix.cc
+++ b/src/core/lib/iomgr/socket_utils_common_posix.cc
@@ -339,6 +339,10 @@ uint16_t grpc_htons(uint16_t hostshort) { return htons(hostshort); }
 
 uint16_t grpc_ntohs(uint16_t netshort) { return ntohs(netshort); }
 
+uint32_t grpc_htonl(uint32_t hostlong) { return htonl(hostlong); }
+
+uint32_t grpc_ntohl(uint32_t netlong) { return ntohl(netlong); }
+
 int grpc_inet_pton(int af, const char* src, void* dst) {
   return inet_pton(af, src, dst);
 }
diff --git a/src/core/lib/iomgr/socket_utils_uv.cc b/src/core/lib/iomgr/socket_utils_uv.cc
index 7eba40c46b..b5f96b52df 100644
--- a/src/core/lib/iomgr/socket_utils_uv.cc
+++ b/src/core/lib/iomgr/socket_utils_uv.cc
@@ -33,6 +33,10 @@ uint16_t grpc_htons(uint16_t hostshort) { return htons(hostshort); }
 
 uint16_t grpc_ntohs(uint16_t netshort) { return ntohs(netshort); }
 
+uint32_t grpc_htonl(uint32_t hostlong) { return htonl(hostlong); }
+
+uint32_t grpc_ntohl(uint32_t netlong) { return ntohl(netlong); }
+
 int grpc_inet_pton(int af, const char* src, void* dst) {
   return inet_pton(af, src, dst);
 }
diff --git a/src/core/lib/iomgr/socket_utils_windows.cc b/src/core/lib/iomgr/socket_utils_windows.cc
index 3e7b5b812d..9137ab98e6 100644
--- a/src/core/lib/iomgr/socket_utils_windows.cc
+++ b/src/core/lib/iomgr/socket_utils_windows.cc
@@ -31,6 +31,10 @@ uint16_t grpc_htons(uint16_t hostshort) { return htons(hostshort); }
 
 uint16_t grpc_ntohs(uint16_t netshort) { return ntohs(netshort); }
 
+uint32_t grpc_htonl(uint32_t hostlong) { return htonl(hostlong); }
+
+uint32_t grpc_ntohl(uint32_t netlong) { return ntohl(netlong); }
+
 int grpc_inet_pton(int af, const char* src, void* dst) {
   return inet_pton(af, src, dst);
 }
diff --git a/src/core/lib/surface/call.cc b/src/core/lib/surface/call.cc
index 135a128aae..556eb234b4 100644
--- a/src/core/lib/surface/call.cc
+++ b/src/core/lib/surface/call.cc
@@ -489,6 +489,12 @@ grpc_error* grpc_call_create(const grpc_call_create_args* args,
                                                &call->pollent);
   }
 
+  grpc_core::channelz::ChannelNode* channelz_channel =
+      grpc_channel_get_channelz_node(call->channel);
+  if (channelz_channel != nullptr) {
+    channelz_channel->RecordCallStarted();
+  }
+
   grpc_slice_unref_internal(path);
 
   return error;
@@ -531,7 +537,6 @@ static void release_call(void* call, grpc_error* error) {
   GRPC_CHANNEL_INTERNAL_UNREF(channel, "call");
 }
 
-static void set_status_value_directly(grpc_status_code status, void* dest);
 static void destroy_call(void* call, grpc_error* error) {
   GPR_TIMER_SCOPE("destroy_call", 0);
   size_t i;
@@ -1087,13 +1092,12 @@ static void recv_trailing_filter(void* args, grpc_metadata_batch* b) {
   if (b->idx.named.grpc_status != nullptr) {
     grpc_status_code status_code =
         grpc_get_status_code_from_metadata(b->idx.named.grpc_status->md);
-    grpc_error* error =
-        status_code == GRPC_STATUS_OK
-            ? GRPC_ERROR_NONE
-            : grpc_error_set_int(GRPC_ERROR_CREATE_FROM_STATIC_STRING(
-                                     "Error received from peer"),
-                                 GRPC_ERROR_INT_GRPC_STATUS,
-                                 static_cast<intptr_t>(status_code));
+    grpc_error* error = GRPC_ERROR_NONE;
+    if (status_code != GRPC_STATUS_OK) {
+      error = grpc_error_set_int(
+          GRPC_ERROR_CREATE_FROM_STATIC_STRING("Error received from peer"),
+          GRPC_ERROR_INT_GRPC_STATUS, static_cast<intptr_t>(status_code));
+    }
     if (b->idx.named.grpc_message != nullptr) {
       error = grpc_error_set_str(
           error, GRPC_ERROR_STR_GRPC_MESSAGE,
@@ -1260,6 +1264,15 @@ static void post_batch_completion(batch_control* bctl) {
       get_final_status(call, set_cancelled_value,
                        call->final_op.server.cancelled, nullptr, nullptr);
     }
+    grpc_core::channelz::ChannelNode* channelz_channel =
+        grpc_channel_get_channelz_node(call->channel);
+    if (channelz_channel != nullptr) {
+      if (*call->final_op.client.status != GRPC_STATUS_OK) {
+        channelz_channel->RecordCallFailed();
+      } else {
+        channelz_channel->RecordCallSucceeded();
+      }
+    }
     GRPC_ERROR_UNREF(error);
     error = GRPC_ERROR_NONE;
   }
diff --git a/src/core/lib/surface/channel.cc b/src/core/lib/surface/channel.cc
index a466b325be..d5d75fcb2a 100644
--- a/src/core/lib/surface/channel.cc
+++ b/src/core/lib/surface/channel.cc
@@ -32,6 +32,7 @@
 
 #include "src/core/lib/channel/channel_args.h"
 #include "src/core/lib/channel/channel_trace.h"
+#include "src/core/lib/channel/channelz.h"
 #include "src/core/lib/debug/stats.h"
 #include "src/core/lib/gpr/string.h"
 #include "src/core/lib/gprpp/manual_constructor.h"
@@ -66,7 +67,7 @@ struct grpc_channel {
   gpr_mu registered_call_mu;
   registered_call* registered_calls;
 
-  grpc_core::RefCountedPtr<grpc_core::ChannelTrace> tracer;
+  grpc_core::RefCountedPtr<grpc_core::channelz::ChannelNode> channelz_channel;
 
   char* target;
 };
@@ -103,6 +104,7 @@ grpc_channel* grpc_channel_create_with_builder(
   channel->target = target;
   channel->is_client = grpc_channel_stack_type_is_client(channel_stack_type);
   size_t channel_tracer_max_nodes = 0;  // default to off
+  bool channelz_enabled = false;
   gpr_mu_init(&channel->registered_call_mu);
   channel->registered_calls = nullptr;
 
@@ -141,15 +143,20 @@ grpc_channel* grpc_channel_create_with_builder(
       const grpc_integer_options options = {0, 0, INT_MAX};
       channel_tracer_max_nodes =
           (size_t)grpc_channel_arg_get_integer(&args->args[i], options);
+    } else if (0 == strcmp(args->args[i].key, GRPC_ARG_ENABLE_CHANNELZ)) {
+      channelz_enabled = grpc_channel_arg_get_bool(&args->args[i], false);
     }
   }
 
   grpc_channel_args_destroy(args);
-  channel->tracer = grpc_core::MakeRefCounted<grpc_core::ChannelTrace>(
-      channel_tracer_max_nodes);
-  channel->tracer->AddTraceEvent(
-      grpc_core::ChannelTrace::Severity::Info,
-      grpc_slice_from_static_string("Channel created"));
+  if (channelz_enabled) {
+    channel->channelz_channel =
+        grpc_core::MakeRefCounted<grpc_core::channelz::ChannelNode>(
+            channel, channel_tracer_max_nodes);
+    channel->channelz_channel->trace()->AddTraceEvent(
+        grpc_core::channelz::ChannelTrace::Severity::Info,
+        grpc_slice_from_static_string("Channel created"));
+  }
   return channel;
 }
 
@@ -184,12 +191,9 @@ static grpc_channel_args* build_channel_args(
   return grpc_channel_args_copy_and_add(input_args, new_args, num_new_args);
 }
 
-char* grpc_channel_get_trace(grpc_channel* channel) {
-  return channel->tracer->RenderTrace();
-}
-
-intptr_t grpc_channel_get_uuid(grpc_channel* channel) {
-  return channel->tracer->GetUuid();
+grpc_core::channelz::ChannelNode* grpc_channel_get_channelz_node(
+    grpc_channel* channel) {
+  return channel->channelz_channel.get();
 }
 
 grpc_channel* grpc_channel_create(const char* target,
@@ -395,6 +399,10 @@ void grpc_channel_internal_unref(grpc_channel* c REF_ARG) {
 
 static void destroy_channel(void* arg, grpc_error* error) {
   grpc_channel* channel = static_cast<grpc_channel*>(arg);
+  if (channel->channelz_channel != nullptr) {
+    channel->channelz_channel->set_channel_destroyed();
+    channel->channelz_channel.reset();
+  }
   grpc_channel_stack_destroy(CHANNEL_STACK_FROM_CHANNEL(channel));
   while (channel->registered_calls) {
     registered_call* rc = channel->registered_calls;
@@ -403,7 +411,6 @@ static void destroy_channel(void* arg, grpc_error* error) {
     GRPC_MDELEM_UNREF(rc->authority);
     gpr_free(rc);
   }
-  channel->tracer.reset();
   gpr_mu_destroy(&channel->registered_call_mu);
   gpr_free(channel->target);
   gpr_free(channel);
diff --git a/src/core/lib/surface/channel.h b/src/core/lib/surface/channel.h
index 288313951e..e5ff2c3596 100644
--- a/src/core/lib/surface/channel.h
+++ b/src/core/lib/surface/channel.h
@@ -23,6 +23,7 @@
 
 #include "src/core/lib/channel/channel_stack.h"
 #include "src/core/lib/channel/channel_stack_builder.h"
+#include "src/core/lib/channel/channelz.h"
 #include "src/core/lib/surface/channel_stack_type.h"
 
 grpc_channel* grpc_channel_create(const char* target,
@@ -50,6 +51,9 @@ grpc_call* grpc_channel_create_pollset_set_call(
 /** Get a (borrowed) pointer to this channels underlying channel stack */
 grpc_channel_stack* grpc_channel_get_channel_stack(grpc_channel* channel);
 
+grpc_core::channelz::ChannelNode* grpc_channel_get_channelz_node(
+    grpc_channel* channel);
+
 /** Get a grpc_mdelem of grpc-status: X where X is the numeric value of
     status_code.
 
diff --git a/src/cpp/README.md b/src/cpp/README.md
index ac76bf74ed..f16cab1f44 100644
--- a/src/cpp/README.md
+++ b/src/cpp/README.md
@@ -1,13 +1,62 @@
 
 # Overview
 
-This directory contains source code for C++ implementation of gRPC.
+A C++ implementation of gRPC
 
-To install gRPC for C++ on your system, follow the instructions to build from source
-[here](../../INSTALL.md). This also installs the protocol buffer compiler
-`protoc` (if you don't have it already), and the C++ gRPC plugin for `protoc`.
+# To start using gRPC C++
 
-# Documentation
+In the C++ world, there's no universally accepted standard for managing project dependencies.
+Therefore, gRPC supports several major build systems, which should satisfy most users.
+
+## bazel
+
+We recommend using Bazel for projects that use gRPC as it will give you the best developer experience
+(easy handling of dependencies that support bazel & fast builds).
+
+To add gRPC as a dependency in bazel:
+1. determine commit SHA for the grpc release you want to use
+2. Use the [http_archive](https://docs.bazel.build/versions/master/be/workspace.html#http_archive) bazel rule to include gRPC source
+  ```
+  http_archive(
+      name = "grpc",
+      urls = [
+          "https://github.com/grpc/grpc/archive/YOUR_GRPC_COMMIT_SHA.tar.gz",
+      ],
+      strip_prefix = "grpc-YOUR_GRPC_COMMIT_SHA",
+  )
+  ```
+
+NOTE: currently bazel is only supported for building gRPC on Linux.
+
+## make
+
+Currently the default choice for building on UNIX based systems is `make`.
+
+To install gRPC for C++ on your system using `make`, follow the [Building gRPC C++](../../BUILDING.md)
+instructions to build from source and then install locally using `make install`.
+This also installs the protocol buffer compiler `protoc` (if you don't have it already),
+and the C++ gRPC plugin for `protoc`.
+
+WARNING: After installing with `make install` there is no easy way to uninstall, which can cause issues
+if you later want to remove the grpc and/or protobuf installation or upgrade to a newer version.
+
+## cmake
+
+`cmake` is the default build option on Windows, but also works on Linux, MacOS. `cmake` has good
+support for crosscompiling and can be used for targeting Android platform.
+
+If your project is using cmake, there are several ways to add gRPC dependency.
+- install gRPC via cmake first and then locate it with `find_package(gRPC CONFIG)`. [Example](../../examples/cpp/helloworld/CMakeLists.txt)
+- via cmake's `ExternalProject_Add` using a technique called "superbuild". [Example](../../examples/cpp/helloworld/cmake_externalproject/CMakeLists.txt)
+- add gRPC source tree to your project (preferrably as a git submodule) and add it to your cmake project with `add_subdirectory`. [Example](../../examples/cpp/helloworld/CMakeLists.txt)
+
+## Packaging systems
+
+There's no standard packaging system for C++. We've looked into supporting some (e.g. Conan and vcpkg) but we are not there yet.
+Contributions and community-maintained packages for popular packaging systems are welcome!
+
+
+## Examples & Additional Documentation
 
 You can find out how to build and run our simplest gRPC C++ example in our
 [C++ quick start](../../examples/cpp).
@@ -25,7 +74,6 @@ documentation site at [grpc.io](https://grpc.io), specifically:
   APIs.
 
 
-# Examples
+# To start developing gRPC C++
 
-Code examples for gRPC C++ live in this repository's
-[examples/cpp](../../examples/cpp) directory.
+For instructions on how to build gRPC C++ from source, follow the [Building gRPC C++](../../BUILDING.md) instructions.
diff --git a/src/cpp/ext/filters/census/client_filter.cc b/src/cpp/ext/filters/census/client_filter.cc
index 293f4b1c25..940d42d100 100644
--- a/src/cpp/ext/filters/census/client_filter.cc
+++ b/src/cpp/ext/filters/census/client_filter.cc
@@ -119,8 +119,10 @@ void CensusClientCallData::StartTransportStreamOpBatch(
   }
   if (op->recv_trailing_metadata() != nullptr) {
     recv_trailing_metadata_ = op->recv_trailing_metadata()->batch();
-    initial_on_done_recv_trailing_metadata_ = op->on_complete();
-    op->set_on_complete(&on_done_recv_trailing_metadata_);
+    initial_on_done_recv_trailing_metadata_ =
+        op->op()->payload->recv_trailing_metadata.recv_trailing_metadata_ready;
+    op->op()->payload->recv_trailing_metadata.recv_trailing_metadata_ready =
+        &on_done_recv_trailing_metadata_;
   }
   // Call next op.
   grpc_call_next_op(elem, op->op());
diff --git a/src/csharp/README.md b/src/csharp/README.md
index e117e66afd..92be4bf1e5 100644
--- a/src/csharp/README.md
+++ b/src/csharp/README.md
@@ -42,7 +42,7 @@ If you are a user of gRPC C#, go to Usage section above.
 
 - [dotnet SDK](https://www.microsoft.com/net/core)
 - [Mono 4+](https://www.mono-project.com/) (only needed for Linux and MacOS)
-- Prerequisites mentioned in [INSTALL.md](../../INSTALL.md#pre-requisites)
+- Prerequisites mentioned in [BUILDING.md](../../BUILDING.md#pre-requisites)
   to be able to compile the native code.
 
 **Windows, Linux or Mac OS X**
@@ -93,6 +93,6 @@ THE NATIVE DEPENDENCY
 
 Internally, gRPC C# uses a native library written in C (gRPC C core) and invokes its functionality via P/Invoke. The fact that a native library is used should be fully transparent to the users and just installing the `Grpc.Core` NuGet package is the only step needed to use gRPC C# on all supported platforms.
 
-[API Reference]: https://grpc.io/grpc/csharp/
+[API Reference]: https://grpc.io/grpc/csharp/api/Grpc.Core.html
 [Helloworld Example]: ../../examples/csharp/helloworld
 [RouteGuide Tutorial]: https://grpc.io/docs/tutorials/basic/csharp.html 
diff --git a/src/proto/grpc/channelz/channelz.proto b/src/proto/grpc/channelz/channelz.proto
index 14db66a654..d930dfcfb4 100644
--- a/src/proto/grpc/channelz/channelz.proto
+++ b/src/proto/grpc/channelz/channelz.proto
@@ -1,4 +1,4 @@
-// Copyright 2018 gRPC authors.
+// Copyright 2018 The gRPC Authors
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -12,20 +12,30 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+// This file defines an interface for exporting monitoring information
+// out of gRPC servers.  See the full design at
+// https://github.com/grpc/proposal/blob/master/A14-channelz.md
+//
+// The canonical version of this proto can be found at
+// https://github.com/grpc/grpc-proto/blob/master/grpc/channelz/v1/channelz.proto
+
 syntax = "proto3";
 
-package grpc.channelz;
+package grpc.channelz.v1;
 
 import "google/protobuf/any.proto";
 import "google/protobuf/duration.proto";
 import "google/protobuf/timestamp.proto";
 import "google/protobuf/wrappers.proto";
 
-// See go/grpc-channelz.
+option go_package = "google.golang.org/grpc/channelz/grpc_channelz_v1";
+option java_multiple_files = true;
+option java_package = "io.grpc.channelz.v1";
+option java_outer_classname = "ChannelzProto";
 
 // Channel is a logical grouping of channels, subchannels, and sockets.
 message Channel {
-  // The identifier for this channel.
+  // The identifier for this channel. This should bet set.
   ChannelRef ref = 1;
   // Data specific to this channel.
   ChannelData data = 2;
@@ -43,7 +53,7 @@ message Channel {
   repeated SubchannelRef subchannel_ref = 4;
 
   // There are no ordering guarantees on the order of sockets.
-  repeated SocketRef socket = 5;
+  repeated SocketRef socket_ref = 5;
 }
 
 // Subchannel is a logical grouping of channels, subchannels, and sockets.
@@ -67,7 +77,7 @@ message Subchannel {
   repeated SubchannelRef subchannel_ref = 4;
 
   // There are no ordering guarantees on the order of sockets.
-  repeated SocketRef socket = 5;
+  repeated SocketRef socket_ref = 5;
 }
 
 // These come from the specified states in this document:
@@ -84,20 +94,23 @@ message ChannelConnectivityState {
   State state = 1;
 }
 
+// Channel data is data related to a specific Channel or Subchannel.
 message ChannelData {
-
+  // The connectivity state of the channel or subchannel.  Implementations
+  // should always set this.
   ChannelConnectivityState state = 1;
 
   // The target this channel originally tried to connect to.  May be absent
   string target = 2;
 
+  // A trace of recent events on the channel.  May be absent.
   ChannelTrace trace = 3;
 
   // The number of calls started on the channel
   int64 calls_started = 4;
   // The number of calls that have completed with an OK status
   int64 calls_succeeded = 5;
-  // The number of calls that have a completed with a non-OK status
+  // The number of calls that have completed with a non-OK status
   int64 calls_failed = 6;
 
   // The last time a call was started on the channel.
@@ -130,26 +143,29 @@ message ChannelTraceEvent {
   }
 }
 
+// ChannelTrace represents the recent events that have occurred on the channel.
 message ChannelTrace {
   // Number of events ever logged in this tracing object. This can differ from
   // events.size() because events can be overwritten or garbage collected by
   // implementations.
   int64 num_events_logged = 1;
   // Time that this channel was created.
-  google.protobuf.Timestamp creation_time = 2;
+  google.protobuf.Timestamp creation_timestamp = 2;
   // List of events that have occurred on this channel.
   repeated ChannelTraceEvent events = 3;
 }
 
+// ChannelRef is a reference to a Channel.
 message ChannelRef {
   // The globally unique id for this channel.  Must be a positive number.
   int64 channel_id = 1;
   // An optional name associated with the channel.
   string name = 2;
   // Intentionally don't use field numbers from other refs.
-  reserved 3, 4, 5, 6;
+  reserved 3, 4, 5, 6, 7, 8;
 }
 
+// ChannelRef is a reference to a Subchannel.
 message SubchannelRef {
   // The globally unique id for this subchannel.  Must be a positive number.
   int64 subchannel_id = 7;
@@ -159,6 +175,7 @@ message SubchannelRef {
   reserved 1, 2, 3, 4, 5, 6;
 }
 
+// SocketRef is a reference to a Socket.
 message SocketRef {
   int64 socket_id = 3;
   // An optional name associated with the socket.
@@ -167,8 +184,9 @@ message SocketRef {
   reserved 1, 2, 5, 6, 7, 8;
 }
 
+// ServerRef is a reference to a Server.
 message ServerRef {
-  // A globally unique identifier for this server.   Must be a positive number.
+  // A globally unique identifier for this server.  Must be a positive number.
   int64 server_id = 5;
   // An optional name associated with the server.
   string name = 6;
@@ -176,16 +194,22 @@ message ServerRef {
   reserved 1, 2, 3, 4, 7, 8;
 }
 
+// Server represents a single server.  There may be multiple servers in a single
+// program.
 message Server {
+  // The identifier for a Server.  This should be set.
   ServerRef ref = 1;
+  // The associated data of the Server.
   ServerData data = 2;
 
   // The sockets that the server is listening on.  There are no ordering
-  // guarantees.
+  // guarantees.  This may be absent.
   repeated SocketRef listen_socket = 3;
 }
 
+// ServerData is data for a specific Server.
 message ServerData {
+  // A trace of recent events on the server.  May be absent.
   ChannelTrace trace = 1;
 
   // The number of incoming calls started on the server
@@ -201,13 +225,17 @@ message ServerData {
 
 // Information about an actual connection.  Pronounced "sock-ay".
 message Socket {
+  // The identifier for the Socket.
   SocketRef ref = 1;
 
+  // Data specific to this Socket.
   SocketData data = 2;
   // The locally bound address.
   Address local = 3;
   // The remote bound address.  May be absent.
   Address remote = 4;
+  // Security details for this socket.  May be absent if not available, or
+  // there is no security on the socket.
   Security security = 5;
 
   // Optional, represents the name of the remote endpoint, if different than
@@ -215,17 +243,23 @@ message Socket {
   string remote_name = 6;
 }
 
+// SocketData is data associated for a specific Socket.  The fields present
+// are specific to the implementation, so there may be minor differences in
+// the semantics.  (e.g. flow control windows)
 message SocketData {
   // The number of streams that have been started.
   int64 streams_started = 1;
-  // The number of streams that have ended successfully with the EoS bit set for
-  //  both end points
+  // The number of streams that have ended successfully:
+  // On client side, received frame with eos bit set;
+  // On server side, sent frame with eos bit set.
   int64 streams_succeeded = 2;
-  // The number of incoming streams that have a completed with a non-OK status
+  // The number of streams that have ended unsuccessfully:
+  // On client side, ended without receiving frame with eos bit set;
+  // On server side, ended without sending frame with eos bit set.
   int64 streams_failed = 3;
-
-  // The number of messages successfully sent on this socket.
+  // The number of grpc messages successfully sent on this socket.
   int64 messages_sent = 4;
+  // The number of grpc messages received on this socket.
   int64 messages_received = 5;
 
   // The number of keep alives sent.  This is typically implemented with HTTP/2
@@ -254,12 +288,14 @@ message SocketData {
   // include stream level or TCP level flow control info.
   google.protobuf.Int64Value  remote_flow_control_window = 12;
 
+  // Socket options set on this socket.  May be absent.
   repeated SocketOption option = 13;
 }
 
+// Address represents the address used to create the socket.
 message Address {
   message TcpIpAddress {
-    // Either the IPv4 or IPv6 address in bytes.  Will either be 4 bytes or 16
+    // Either the IPv4 or IPv6 address in bytes.  Will be either 4 bytes or 16
     // bytes in length.
     bytes ip_address = 1;
     // 0-64k, or -1 if not appropriate.
@@ -271,7 +307,7 @@ message Address {
   }
   // An address type not included above.
   message OtherAddress {
-    // The human readable version of the value.
+    // The human readable version of the value.  This value should be set.
     string name = 1;
     // The actual address message.
     google.protobuf.Any value = 2;
@@ -284,12 +320,17 @@ message Address {
   }
 }
 
+// Security represents details about how secure the socket is.
 message Security {
   message Tls {
-    // The key exchange used.  e.g. X25519
-    string key_exchange = 1;
-    // The cipher used. e.g. AES_128_GCM.
-    string cipher = 2;
+    oneof cipher_suite {
+      // The cipher suite name in the RFC 4346 format:
+      // https://tools.ietf.org/html/rfc4346#appendix-C
+      string standard_name = 1;
+      // Some other way to describe the cipher suite if
+      // the RFC 4346 name is not available.
+      string other_name = 2;
+    }
     // the certificate used by this endpoint.
     bytes local_certificate = 3;
     // the certificate used by the remote endpoint.
@@ -307,7 +348,11 @@ message Security {
   }
 }
 
+// SocketOption represents socket options for a socket.  Specifically, these
+// are the options returned by getsockopt().
 message SocketOption {
+  // The full name of the socket option.  Typically this will be the upper case
+  // name, such as "SO_REUSEPORT".
   string name = 1;
   // The human readable value of this socket option.  At least one of value or
   // additional will be set.
@@ -323,12 +368,17 @@ message SocketOptionTimeout {
   google.protobuf.Duration duration = 1;
 }
 
+// For use with SocketOption's additional field.  This is primarily used for
+// SO_LINGER.
 message SocketOptionLinger {
+  // active maps to `struct linger.l_onoff`
   bool active = 1;
+  // duration maps to `struct linger.l_linger`
   google.protobuf.Duration duration = 2;
 }
 
-// Tcp info for SOL_TCP, TCP_INFO
+// For use with SocketOption's additional field.  Tcp info for
+// SOL_TCP and TCP_INFO.
 message SocketOptionTcpInfo {
   uint32 tcpi_state = 1;
 
@@ -366,8 +416,10 @@ message SocketOptionTcpInfo {
   uint32 tcpi_reordering = 29;
 }
 
+// Channelz is a service exposed by gRPC servers that provides detailed debug
+// information.
 service Channelz {
-  // Gets all root channels (e.g. channels the application has directly
+  // Gets all root channels (i.e. channels the application has directly
   // created). This does not include subchannels nor non-top level channels.
   rpc GetTopChannels(GetTopChannelsRequest) returns (GetTopChannelsResponse);
   // Gets all servers that exist in the process.
@@ -382,6 +434,22 @@ service Channelz {
   rpc GetSocket(GetSocketRequest) returns (GetSocketResponse);
 }
 
+message GetTopChannelsRequest {
+  // start_channel_id indicates that only channels at or above this id should be
+  // included in the results.
+  int64 start_channel_id = 1;
+}
+
+message GetTopChannelsResponse {
+  // list of channels that the connection detail service knows about.  Sorted in
+  // ascending channel_id order.
+  repeated Channel channel = 1;
+  // If set, indicates that the list of channels is the final list.  Requesting
+  // more channels can only return more if they are created after this RPC
+  // completes.
+  bool end = 2;
+}
+
 message GetServersRequest {
   // start_server_id indicates that only servers at or above this id should be
   // included in the results.
@@ -415,42 +483,35 @@ message GetServerSocketsResponse {
   bool end = 2;
 }
 
-message GetTopChannelsRequest {
-  // start_channel_id indicates that only channels at or above this id should be
-  // included in the results.
-  int64 start_channel_id = 1;
-}
-
-message GetTopChannelsResponse {
-  // list of channels that the connection detail service knows about.  Sorted in
-  // ascending channel_id order.
-  repeated Channel channel = 1;
-  // If set, indicates that the list of channels is the final list.  Requesting
-  // more channels can only return more if they are created after this RPC
-  // completes.
-  bool end = 2;
-}
-
 message GetChannelRequest {
+  // channel_id is the identifier of the specific channel to get.
   int64 channel_id = 1;
 }
 
 message GetChannelResponse {
+  // The Channel that corresponds to the requested channel_id.  This field
+  // should be set.
   Channel channel = 1;
 }
 
 message GetSubchannelRequest {
+  // subchannel_id is the identifier of the specific subchannel to get.
   int64 subchannel_id = 1;
 }
 
 message GetSubchannelResponse {
+  // The Subchannel that corresponds to the requested subchannel_id.  This
+  // field should be set.
   Subchannel subchannel = 1;
 }
 
 message GetSocketRequest {
+  // socket_id is the identifier of the specific socket to get.
   int64 socket_id = 1;
 }
 
 message GetSocketResponse {
+  // The Socket that corresponds to the requested socket_id.  This field
+  // should be set.
   Socket socket = 1;
 }
diff --git a/src/python/grpcio/grpc_core_dependencies.py b/src/python/grpcio/grpc_core_dependencies.py
index f53a6c9be2..b20b8155a0 100644
--- a/src/python/grpcio/grpc_core_dependencies.py
+++ b/src/python/grpcio/grpc_core_dependencies.py
@@ -64,6 +64,7 @@ CORE_SOURCE_FILES = [
     'src/core/lib/channel/channel_stack.cc',
     'src/core/lib/channel/channel_stack_builder.cc',
     'src/core/lib/channel/channel_trace.cc',
+    'src/core/lib/channel/channelz.cc',
     'src/core/lib/channel/channelz_registry.cc',
     'src/core/lib/channel/connected_channel.cc',
     'src/core/lib/channel/handshaker.cc',
diff --git a/src/python/grpcio_testing/MANIFEST.in b/src/python/grpcio_testing/MANIFEST.in
new file mode 100644
index 0000000000..39b3565217
--- /dev/null
+++ b/src/python/grpcio_testing/MANIFEST.in
@@ -0,0 +1,3 @@
+include grpc_version.py
+recursive-include grpc_testing *.py
+global-exclude *.pyc
diff --git a/src/python/grpcio_testing/README.rst b/src/python/grpcio_testing/README.rst
new file mode 100644
index 0000000000..c699b80fb6
--- /dev/null
+++ b/src/python/grpcio_testing/README.rst
@@ -0,0 +1,10 @@
+gRPC Python Testing Package
+===========================
+
+Testing utilities for gRPC Python
+
+Dependencies
+------------
+
+Depends on the `grpcio` package, available from PyPI via `pip install grpcio`.
+
diff --git a/src/ruby/end2end/multiple_killed_watching_threads_driver.rb b/src/ruby/end2end/multiple_killed_watching_threads_driver.rb
index 8ec2073d98..7b39f5a347 100755
--- a/src/ruby/end2end/multiple_killed_watching_threads_driver.rb
+++ b/src/ruby/end2end/multiple_killed_watching_threads_driver.rb
@@ -58,10 +58,6 @@ def main
   run_multiple_killed_watches(10, 0.1)
   STDERR.puts '1000 iterations, sleep 0.001 before killing thread'
   run_multiple_killed_watches(1000, 0.001)
-  STDERR.puts '10000 iterations, sleep 0.00001 before killing thread'
-  run_multiple_killed_watches(10_000, 0.00001)
-  STDERR.puts '20000 iterations, sleep 0.00001 before killing thread'
-  run_multiple_killed_watches(20_000, 0.00001)
 end
 
 main
diff --git a/src/ruby/ext/grpc/rb_grpc_imports.generated.c b/src/ruby/ext/grpc/rb_grpc_imports.generated.c
index 02f84c0b96..031699ce8e 100644
--- a/src/ruby/ext/grpc/rb_grpc_imports.generated.c
+++ b/src/ruby/ext/grpc/rb_grpc_imports.generated.c
@@ -68,8 +68,6 @@ grpc_channel_get_info_type grpc_channel_get_info_import;
 grpc_insecure_channel_create_type grpc_insecure_channel_create_import;
 grpc_lame_client_channel_create_type grpc_lame_client_channel_create_import;
 grpc_channel_destroy_type grpc_channel_destroy_import;
-grpc_channel_get_trace_type grpc_channel_get_trace_import;
-grpc_channel_get_uuid_type grpc_channel_get_uuid_import;
 grpc_call_cancel_type grpc_call_cancel_import;
 grpc_call_cancel_with_status_type grpc_call_cancel_with_status_import;
 grpc_call_ref_type grpc_call_ref_import;
@@ -316,8 +314,6 @@ void grpc_rb_load_imports(HMODULE library) {
   grpc_insecure_channel_create_import = (grpc_insecure_channel_create_type) GetProcAddress(library, "grpc_insecure_channel_create");
   grpc_lame_client_channel_create_import = (grpc_lame_client_channel_create_type) GetProcAddress(library, "grpc_lame_client_channel_create");
   grpc_channel_destroy_import = (grpc_channel_destroy_type) GetProcAddress(library, "grpc_channel_destroy");
-  grpc_channel_get_trace_import = (grpc_channel_get_trace_type) GetProcAddress(library, "grpc_channel_get_trace");
-  grpc_channel_get_uuid_import = (grpc_channel_get_uuid_type) GetProcAddress(library, "grpc_channel_get_uuid");
   grpc_call_cancel_import = (grpc_call_cancel_type) GetProcAddress(library, "grpc_call_cancel");
   grpc_call_cancel_with_status_import = (grpc_call_cancel_with_status_type) GetProcAddress(library, "grpc_call_cancel_with_status");
   grpc_call_ref_import = (grpc_call_ref_type) GetProcAddress(library, "grpc_call_ref");
diff --git a/src/ruby/ext/grpc/rb_grpc_imports.generated.h b/src/ruby/ext/grpc/rb_grpc_imports.generated.h
index 46d3bf5a33..474405ae3f 100644
--- a/src/ruby/ext/grpc/rb_grpc_imports.generated.h
+++ b/src/ruby/ext/grpc/rb_grpc_imports.generated.h
@@ -179,12 +179,6 @@ extern grpc_lame_client_channel_create_type grpc_lame_client_channel_create_impo
 typedef void(*grpc_channel_destroy_type)(grpc_channel* channel);
 extern grpc_channel_destroy_type grpc_channel_destroy_import;
 #define grpc_channel_destroy grpc_channel_destroy_import
-typedef char*(*grpc_channel_get_trace_type)(grpc_channel* channel);
-extern grpc_channel_get_trace_type grpc_channel_get_trace_import;
-#define grpc_channel_get_trace grpc_channel_get_trace_import
-typedef intptr_t(*grpc_channel_get_uuid_type)(grpc_channel* channel);
-extern grpc_channel_get_uuid_type grpc_channel_get_uuid_import;
-#define grpc_channel_get_uuid grpc_channel_get_uuid_import
 typedef grpc_call_error(*grpc_call_cancel_type)(grpc_call* call, void* reserved);
 extern grpc_call_cancel_type grpc_call_cancel_import;
 #define grpc_call_cancel grpc_call_cancel_import
diff --git a/src/ruby/lib/grpc/generic/active_call.rb b/src/ruby/lib/grpc/generic/active_call.rb
index 86240814bd..6e601bdc91 100644
--- a/src/ruby/lib/grpc/generic/active_call.rb
+++ b/src/ruby/lib/grpc/generic/active_call.rb
@@ -120,7 +120,7 @@ module GRPC
       @send_initial_md_mutex.synchronize do
         return if @metadata_sent
         @metadata_to_send.merge!(new_metadata)
-        @metadata_tag = ActiveCall.client_invoke(@call, @metadata_to_send)
+        ActiveCall.client_invoke(@call, @metadata_to_send)
         @metadata_sent = true
       end
     end