Merge github.com:grpc/grpc into pollset_kick_stats

80 files changed, 1807 insertions, 1279 deletions

diff --git a/src/compiler/cpp_generator.cc b/src/compiler/cpp_generator.cc
index b09bf99677..c2db8eff71 100644
--- a/src/compiler/cpp_generator.cc
+++ b/src/compiler/cpp_generator.cc
@@ -165,25 +165,37 @@ void PrintHeaderClientMethodInterfaces(
   (*vars)["Request"] = method->input_type_name();
   (*vars)["Response"] = method->output_type_name();
 
+  struct {
+    grpc::string prefix;
+    grpc::string method_params;  // extra arguments to method
+    grpc::string raw_args;       // extra arguments to raw version of method
+  } async_prefixes[] = {{"Async", ", void* tag", ", tag"},
+                        {"PrepareAsync", "", ""}};
+
   if (is_public) {
     if (method->NoStreaming()) {
       printer->Print(
           *vars,
           "virtual ::grpc::Status $Method$(::grpc::ClientContext* context, "
           "const $Request$& request, $Response$* response) = 0;\n");
-      printer->Print(*vars,
-                     "std::unique_ptr< "
-                     "::grpc::ClientAsyncResponseReaderInterface< $Response$>> "
-                     "Async$Method$(::grpc::ClientContext* context, "
-                     "const $Request$& request, "
-                     "::grpc::CompletionQueue* cq) {\n");
-      printer->Indent();
-      printer->Print(*vars,
-                     "return std::unique_ptr< "
-                     "::grpc::ClientAsyncResponseReaderInterface< $Response$>>("
-                     "Async$Method$Raw(context, request, cq));\n");
-      printer->Outdent();
-      printer->Print("}\n");
+      for (auto async_prefix : async_prefixes) {
+        (*vars)["AsyncPrefix"] = async_prefix.prefix;
+        printer->Print(
+            *vars,
+            "std::unique_ptr< "
+            "::grpc::ClientAsyncResponseReaderInterface< $Response$>> "
+            "$AsyncPrefix$$Method$(::grpc::ClientContext* context, "
+            "const $Request$& request, "
+            "::grpc::CompletionQueue* cq) {\n");
+        printer->Indent();
+        printer->Print(
+            *vars,
+            "return std::unique_ptr< "
+            "::grpc::ClientAsyncResponseReaderInterface< $Response$>>("
+            "$AsyncPrefix$$Method$Raw(context, request, cq));\n");
+        printer->Outdent();
+        printer->Print("}\n");
+      }
     } else if (ClientOnlyStreaming(method)) {
       printer->Print(
           *vars,
@@ -197,19 +209,26 @@ void PrintHeaderClientMethodInterfaces(
           "($Method$Raw(context, response));\n");
       printer->Outdent();
       printer->Print("}\n");
-      printer->Print(
-          *vars,
-          "std::unique_ptr< ::grpc::ClientAsyncWriterInterface< $Request$>>"
-          " Async$Method$(::grpc::ClientContext* context, $Response$* "
-          "response, "
-          "::grpc::CompletionQueue* cq, void* tag) {\n");
-      printer->Indent();
-      printer->Print(*vars,
-                     "return std::unique_ptr< "
-                     "::grpc::ClientAsyncWriterInterface< $Request$>>("
-                     "Async$Method$Raw(context, response, cq, tag));\n");
-      printer->Outdent();
-      printer->Print("}\n");
+      for (auto async_prefix : async_prefixes) {
+        (*vars)["AsyncPrefix"] = async_prefix.prefix;
+        (*vars)["AsyncMethodParams"] = async_prefix.method_params;
+        (*vars)["AsyncRawArgs"] = async_prefix.raw_args;
+        printer->Print(
+            *vars,
+            "std::unique_ptr< ::grpc::ClientAsyncWriterInterface< $Request$>>"
+            " $AsyncPrefix$$Method$(::grpc::ClientContext* context, "
+            "$Response$* "
+            "response, "
+            "::grpc::CompletionQueue* cq$AsyncMethodParams$) {\n");
+        printer->Indent();
+        printer->Print(*vars,
+                       "return std::unique_ptr< "
+                       "::grpc::ClientAsyncWriterInterface< $Request$>>("
+                       "$AsyncPrefix$$Method$Raw(context, response, "
+                       "cq$AsyncRawArgs$));\n");
+        printer->Outdent();
+        printer->Print("}\n");
+      }
     } else if (ServerOnlyStreaming(method)) {
       printer->Print(
           *vars,
@@ -223,19 +242,25 @@ void PrintHeaderClientMethodInterfaces(
           "($Method$Raw(context, request));\n");
       printer->Outdent();
       printer->Print("}\n");
-      printer->Print(
-          *vars,
-          "std::unique_ptr< ::grpc::ClientAsyncReaderInterface< $Response$>> "
-          "Async$Method$("
-          "::grpc::ClientContext* context, const $Request$& request, "
-          "::grpc::CompletionQueue* cq, void* tag) {\n");
-      printer->Indent();
-      printer->Print(*vars,
-                     "return std::unique_ptr< "
-                     "::grpc::ClientAsyncReaderInterface< $Response$>>("
-                     "Async$Method$Raw(context, request, cq, tag));\n");
-      printer->Outdent();
-      printer->Print("}\n");
+      for (auto async_prefix : async_prefixes) {
+        (*vars)["AsyncPrefix"] = async_prefix.prefix;
+        (*vars)["AsyncMethodParams"] = async_prefix.method_params;
+        (*vars)["AsyncRawArgs"] = async_prefix.raw_args;
+        printer->Print(
+            *vars,
+            "std::unique_ptr< ::grpc::ClientAsyncReaderInterface< $Response$>> "
+            "$AsyncPrefix$$Method$("
+            "::grpc::ClientContext* context, const $Request$& request, "
+            "::grpc::CompletionQueue* cq$AsyncMethodParams$) {\n");
+        printer->Indent();
+        printer->Print(
+            *vars,
+            "return std::unique_ptr< "
+            "::grpc::ClientAsyncReaderInterface< $Response$>>("
+            "$AsyncPrefix$$Method$Raw(context, request, cq$AsyncRawArgs$));\n");
+        printer->Outdent();
+        printer->Print("}\n");
+      }
     } else if (method->BidiStreaming()) {
       printer->Print(*vars,
                      "std::unique_ptr< ::grpc::ClientReaderWriterInterface< "
@@ -249,61 +274,83 @@ void PrintHeaderClientMethodInterfaces(
           "$Method$Raw(context));\n");
       printer->Outdent();
       printer->Print("}\n");
-      printer->Print(
-          *vars,
-          "std::unique_ptr< "
-          "::grpc::ClientAsyncReaderWriterInterface< $Request$, $Response$>> "
-          "Async$Method$(::grpc::ClientContext* context, "
-          "::grpc::CompletionQueue* cq, void* tag) {\n");
-      printer->Indent();
-      printer->Print(
-          *vars,
-          "return std::unique_ptr< "
-          "::grpc::ClientAsyncReaderWriterInterface< $Request$, $Response$>>("
-          "Async$Method$Raw(context, cq, tag));\n");
-      printer->Outdent();
-      printer->Print("}\n");
+      for (auto async_prefix : async_prefixes) {
+        (*vars)["AsyncPrefix"] = async_prefix.prefix;
+        (*vars)["AsyncMethodParams"] = async_prefix.method_params;
+        (*vars)["AsyncRawArgs"] = async_prefix.raw_args;
+        printer->Print(
+            *vars,
+            "std::unique_ptr< "
+            "::grpc::ClientAsyncReaderWriterInterface< $Request$, $Response$>> "
+            "$AsyncPrefix$$Method$(::grpc::ClientContext* context, "
+            "::grpc::CompletionQueue* cq$AsyncMethodParams$) {\n");
+        printer->Indent();
+        printer->Print(
+            *vars,
+            "return std::unique_ptr< "
+            "::grpc::ClientAsyncReaderWriterInterface< $Request$, $Response$>>("
+            "$AsyncPrefix$$Method$Raw(context, cq$AsyncRawArgs$));\n");
+        printer->Outdent();
+        printer->Print("}\n");
+      }
     }
   } else {
     if (method->NoStreaming()) {
-      printer->Print(
-          *vars,
-          "virtual ::grpc::ClientAsyncResponseReaderInterface< $Response$>* "
-          "Async$Method$Raw(::grpc::ClientContext* context, "
-          "const $Request$& request, "
-          "::grpc::CompletionQueue* cq) = 0;\n");
+      for (auto async_prefix : async_prefixes) {
+        (*vars)["AsyncPrefix"] = async_prefix.prefix;
+        printer->Print(
+            *vars,
+            "virtual ::grpc::ClientAsyncResponseReaderInterface< $Response$>* "
+            "$AsyncPrefix$$Method$Raw(::grpc::ClientContext* context, "
+            "const $Request$& request, "
+            "::grpc::CompletionQueue* cq) = 0;\n");
+      }
     } else if (ClientOnlyStreaming(method)) {
       printer->Print(
           *vars,
           "virtual ::grpc::ClientWriterInterface< $Request$>*"
           " $Method$Raw("
           "::grpc::ClientContext* context, $Response$* response) = 0;\n");
-      printer->Print(*vars,
-                     "virtual ::grpc::ClientAsyncWriterInterface< $Request$>*"
-                     " Async$Method$Raw(::grpc::ClientContext* context, "
-                     "$Response$* response, "
-                     "::grpc::CompletionQueue* cq, void* tag) = 0;\n");
+      for (auto async_prefix : async_prefixes) {
+        (*vars)["AsyncPrefix"] = async_prefix.prefix;
+        (*vars)["AsyncMethodParams"] = async_prefix.method_params;
+        printer->Print(
+            *vars,
+            "virtual ::grpc::ClientAsyncWriterInterface< $Request$>*"
+            " $AsyncPrefix$$Method$Raw(::grpc::ClientContext* context, "
+            "$Response$* response, "
+            "::grpc::CompletionQueue* cq$AsyncMethodParams$) = 0;\n");
+      }
     } else if (ServerOnlyStreaming(method)) {
       printer->Print(
           *vars,
           "virtual ::grpc::ClientReaderInterface< $Response$>* $Method$Raw("
           "::grpc::ClientContext* context, const $Request$& request) = 0;\n");
-      printer->Print(
-          *vars,
-          "virtual ::grpc::ClientAsyncReaderInterface< $Response$>* "
-          "Async$Method$Raw("
-          "::grpc::ClientContext* context, const $Request$& request, "
-          "::grpc::CompletionQueue* cq, void* tag) = 0;\n");
+      for (auto async_prefix : async_prefixes) {
+        (*vars)["AsyncPrefix"] = async_prefix.prefix;
+        (*vars)["AsyncMethodParams"] = async_prefix.method_params;
+        printer->Print(
+            *vars,
+            "virtual ::grpc::ClientAsyncReaderInterface< $Response$>* "
+            "$AsyncPrefix$$Method$Raw("
+            "::grpc::ClientContext* context, const $Request$& request, "
+            "::grpc::CompletionQueue* cq$AsyncMethodParams$) = 0;\n");
+      }
     } else if (method->BidiStreaming()) {
       printer->Print(*vars,
                      "virtual ::grpc::ClientReaderWriterInterface< $Request$, "
                      "$Response$>* "
                      "$Method$Raw(::grpc::ClientContext* context) = 0;\n");
-      printer->Print(*vars,
-                     "virtual ::grpc::ClientAsyncReaderWriterInterface< "
-                     "$Request$, $Response$>* "
-                     "Async$Method$Raw(::grpc::ClientContext* context, "
-                     "::grpc::CompletionQueue* cq, void* tag) = 0;\n");
+      for (auto async_prefix : async_prefixes) {
+        (*vars)["AsyncPrefix"] = async_prefix.prefix;
+        (*vars)["AsyncMethodParams"] = async_prefix.method_params;
+        printer->Print(
+            *vars,
+            "virtual ::grpc::ClientAsyncReaderWriterInterface< "
+            "$Request$, $Response$>* "
+            "$AsyncPrefix$$Method$Raw(::grpc::ClientContext* context, "
+            "::grpc::CompletionQueue* cq$AsyncMethodParams$) = 0;\n");
+      }
     }
   }
 }
@@ -315,25 +362,35 @@ void PrintHeaderClientMethod(grpc_generator::Printer *printer,
   (*vars)["Method"] = method->name();
   (*vars)["Request"] = method->input_type_name();
   (*vars)["Response"] = method->output_type_name();
+  struct {
+    grpc::string prefix;
+    grpc::string method_params;  // extra arguments to method
+    grpc::string raw_args;       // extra arguments to raw version of method
+  } async_prefixes[] = {{"Async", ", void* tag", ", tag"},
+                        {"PrepareAsync", "", ""}};
+
   if (is_public) {
     if (method->NoStreaming()) {
       printer->Print(
           *vars,
           "::grpc::Status $Method$(::grpc::ClientContext* context, "
           "const $Request$& request, $Response$* response) override;\n");
-      printer->Print(
-          *vars,
-          "std::unique_ptr< ::grpc::ClientAsyncResponseReader< $Response$>> "
-          "Async$Method$(::grpc::ClientContext* context, "
-          "const $Request$& request, "
-          "::grpc::CompletionQueue* cq) {\n");
-      printer->Indent();
-      printer->Print(*vars,
-                     "return std::unique_ptr< "
-                     "::grpc::ClientAsyncResponseReader< $Response$>>("
-                     "Async$Method$Raw(context, request, cq));\n");
-      printer->Outdent();
-      printer->Print("}\n");
+      for (auto async_prefix : async_prefixes) {
+        (*vars)["AsyncPrefix"] = async_prefix.prefix;
+        printer->Print(
+            *vars,
+            "std::unique_ptr< ::grpc::ClientAsyncResponseReader< $Response$>> "
+            "$AsyncPrefix$$Method$(::grpc::ClientContext* context, "
+            "const $Request$& request, "
+            "::grpc::CompletionQueue* cq) {\n");
+        printer->Indent();
+        printer->Print(*vars,
+                       "return std::unique_ptr< "
+                       "::grpc::ClientAsyncResponseReader< $Response$>>("
+                       "$AsyncPrefix$$Method$Raw(context, request, cq));\n");
+        printer->Outdent();
+        printer->Print("}\n");
+      }
     } else if (ClientOnlyStreaming(method)) {
       printer->Print(
           *vars,
@@ -346,18 +403,24 @@ void PrintHeaderClientMethod(grpc_generator::Printer *printer,
                      "($Method$Raw(context, response));\n");
       printer->Outdent();
       printer->Print("}\n");
-      printer->Print(*vars,
-                     "std::unique_ptr< ::grpc::ClientAsyncWriter< $Request$>>"
-                     " Async$Method$(::grpc::ClientContext* context, "
-                     "$Response$* response, "
-                     "::grpc::CompletionQueue* cq, void* tag) {\n");
-      printer->Indent();
-      printer->Print(
-          *vars,
-          "return std::unique_ptr< ::grpc::ClientAsyncWriter< $Request$>>("
-          "Async$Method$Raw(context, response, cq, tag));\n");
-      printer->Outdent();
-      printer->Print("}\n");
+      for (auto async_prefix : async_prefixes) {
+        (*vars)["AsyncPrefix"] = async_prefix.prefix;
+        (*vars)["AsyncMethodParams"] = async_prefix.method_params;
+        (*vars)["AsyncRawArgs"] = async_prefix.raw_args;
+        printer->Print(*vars,
+                       "std::unique_ptr< ::grpc::ClientAsyncWriter< $Request$>>"
+                       " $AsyncPrefix$$Method$(::grpc::ClientContext* context, "
+                       "$Response$* response, "
+                       "::grpc::CompletionQueue* cq$AsyncMethodParams$) {\n");
+        printer->Indent();
+        printer->Print(
+            *vars,
+            "return std::unique_ptr< ::grpc::ClientAsyncWriter< $Request$>>("
+            "$AsyncPrefix$$Method$Raw(context, response, "
+            "cq$AsyncRawArgs$));\n");
+        printer->Outdent();
+        printer->Print("}\n");
+      }
     } else if (ServerOnlyStreaming(method)) {
       printer->Print(
           *vars,
@@ -371,19 +434,24 @@ void PrintHeaderClientMethod(grpc_generator::Printer *printer,
           "($Method$Raw(context, request));\n");
       printer->Outdent();
       printer->Print("}\n");
-      printer->Print(
-          *vars,
-          "std::unique_ptr< ::grpc::ClientAsyncReader< $Response$>> "
-          "Async$Method$("
-          "::grpc::ClientContext* context, const $Request$& request, "
-          "::grpc::CompletionQueue* cq, void* tag) {\n");
-      printer->Indent();
-      printer->Print(
-          *vars,
-          "return std::unique_ptr< ::grpc::ClientAsyncReader< $Response$>>("
-          "Async$Method$Raw(context, request, cq, tag));\n");
-      printer->Outdent();
-      printer->Print("}\n");
+      for (auto async_prefix : async_prefixes) {
+        (*vars)["AsyncPrefix"] = async_prefix.prefix;
+        (*vars)["AsyncMethodParams"] = async_prefix.method_params;
+        (*vars)["AsyncRawArgs"] = async_prefix.raw_args;
+        printer->Print(
+            *vars,
+            "std::unique_ptr< ::grpc::ClientAsyncReader< $Response$>> "
+            "$AsyncPrefix$$Method$("
+            "::grpc::ClientContext* context, const $Request$& request, "
+            "::grpc::CompletionQueue* cq$AsyncMethodParams$) {\n");
+        printer->Indent();
+        printer->Print(
+            *vars,
+            "return std::unique_ptr< ::grpc::ClientAsyncReader< $Response$>>("
+            "$AsyncPrefix$$Method$Raw(context, request, cq$AsyncRawArgs$));\n");
+        printer->Outdent();
+        printer->Print("}\n");
+      }
     } else if (method->BidiStreaming()) {
       printer->Print(
           *vars,
@@ -396,53 +464,80 @@ void PrintHeaderClientMethod(grpc_generator::Printer *printer,
                      "$Method$Raw(context));\n");
       printer->Outdent();
       printer->Print("}\n");
-      printer->Print(*vars,
-                     "std::unique_ptr<  ::grpc::ClientAsyncReaderWriter< "
-                     "$Request$, $Response$>> "
-                     "Async$Method$(::grpc::ClientContext* context, "
-                     "::grpc::CompletionQueue* cq, void* tag) {\n");
-      printer->Indent();
-      printer->Print(*vars,
-                     "return std::unique_ptr< "
-                     "::grpc::ClientAsyncReaderWriter< $Request$, $Response$>>("
-                     "Async$Method$Raw(context, cq, tag));\n");
-      printer->Outdent();
-      printer->Print("}\n");
+      for (auto async_prefix : async_prefixes) {
+        (*vars)["AsyncPrefix"] = async_prefix.prefix;
+        (*vars)["AsyncMethodParams"] = async_prefix.method_params;
+        (*vars)["AsyncRawArgs"] = async_prefix.raw_args;
+        printer->Print(*vars,
+                       "std::unique_ptr<  ::grpc::ClientAsyncReaderWriter< "
+                       "$Request$, $Response$>> "
+                       "$AsyncPrefix$$Method$(::grpc::ClientContext* context, "
+                       "::grpc::CompletionQueue* cq$AsyncMethodParams$) {\n");
+        printer->Indent();
+        printer->Print(
+            *vars,
+            "return std::unique_ptr< "
+            "::grpc::ClientAsyncReaderWriter< $Request$, $Response$>>("
+            "$AsyncPrefix$$Method$Raw(context, cq$AsyncRawArgs$));\n");
+        printer->Outdent();
+        printer->Print("}\n");
+      }
     }
   } else {
     if (method->NoStreaming()) {
-      printer->Print(*vars,
-                     "::grpc::ClientAsyncResponseReader< $Response$>* "
-                     "Async$Method$Raw(::grpc::ClientContext* context, "
-                     "const $Request$& request, "
-                     "::grpc::CompletionQueue* cq) override;\n");
+      for (auto async_prefix : async_prefixes) {
+        (*vars)["AsyncPrefix"] = async_prefix.prefix;
+        printer->Print(
+            *vars,
+            "::grpc::ClientAsyncResponseReader< $Response$>* "
+            "$AsyncPrefix$$Method$Raw(::grpc::ClientContext* context, "
+            "const $Request$& request, "
+            "::grpc::CompletionQueue* cq) override;\n");
+      }
     } else if (ClientOnlyStreaming(method)) {
       printer->Print(*vars,
                      "::grpc::ClientWriter< $Request$>* $Method$Raw("
                      "::grpc::ClientContext* context, $Response$* response) "
                      "override;\n");
-      printer->Print(*vars,
-                     "::grpc::ClientAsyncWriter< $Request$>* Async$Method$Raw("
-                     "::grpc::ClientContext* context, $Response$* response, "
-                     "::grpc::CompletionQueue* cq, void* tag) override;\n");
+      for (auto async_prefix : async_prefixes) {
+        (*vars)["AsyncPrefix"] = async_prefix.prefix;
+        (*vars)["AsyncMethodParams"] = async_prefix.method_params;
+        (*vars)["AsyncRawArgs"] = async_prefix.raw_args;
+        printer->Print(
+            *vars,
+            "::grpc::ClientAsyncWriter< $Request$>* $AsyncPrefix$$Method$Raw("
+            "::grpc::ClientContext* context, $Response$* response, "
+            "::grpc::CompletionQueue* cq$AsyncMethodParams$) override;\n");
+      }
     } else if (ServerOnlyStreaming(method)) {
       printer->Print(*vars,
                      "::grpc::ClientReader< $Response$>* $Method$Raw("
                      "::grpc::ClientContext* context, const $Request$& request)"
                      " override;\n");
-      printer->Print(
-          *vars,
-          "::grpc::ClientAsyncReader< $Response$>* Async$Method$Raw("
-          "::grpc::ClientContext* context, const $Request$& request, "
-          "::grpc::CompletionQueue* cq, void* tag) override;\n");
+      for (auto async_prefix : async_prefixes) {
+        (*vars)["AsyncPrefix"] = async_prefix.prefix;
+        (*vars)["AsyncMethodParams"] = async_prefix.method_params;
+        (*vars)["AsyncRawArgs"] = async_prefix.raw_args;
+        printer->Print(
+            *vars,
+            "::grpc::ClientAsyncReader< $Response$>* $AsyncPrefix$$Method$Raw("
+            "::grpc::ClientContext* context, const $Request$& request, "
+            "::grpc::CompletionQueue* cq$AsyncMethodParams$) override;\n");
+      }
     } else if (method->BidiStreaming()) {
       printer->Print(*vars,
                      "::grpc::ClientReaderWriter< $Request$, $Response$>* "
                      "$Method$Raw(::grpc::ClientContext* context) override;\n");
-      printer->Print(*vars,
-                     "::grpc::ClientAsyncReaderWriter< $Request$, $Response$>* "
-                     "Async$Method$Raw(::grpc::ClientContext* context, "
-                     "::grpc::CompletionQueue* cq, void* tag) override;\n");
+      for (auto async_prefix : async_prefixes) {
+        (*vars)["AsyncPrefix"] = async_prefix.prefix;
+        (*vars)["AsyncMethodParams"] = async_prefix.method_params;
+        (*vars)["AsyncRawArgs"] = async_prefix.raw_args;
+        printer->Print(
+            *vars,
+            "::grpc::ClientAsyncReaderWriter< $Request$, $Response$>* "
+            "$AsyncPrefix$$Method$Raw(::grpc::ClientContext* context, "
+            "::grpc::CompletionQueue* cq$AsyncMethodParams$) override;\n");
+      }
     }
   }
 }
@@ -1077,6 +1172,13 @@ void PrintSourceClientMethod(grpc_generator::Printer *printer,
   (*vars)["Method"] = method->name();
   (*vars)["Request"] = method->input_type_name();
   (*vars)["Response"] = method->output_type_name();
+  struct {
+    grpc::string prefix;
+    grpc::string start;          // bool literal expressed as string
+    grpc::string method_params;  // extra arguments to method
+    grpc::string create_args;    // extra arguments to creator
+  } async_prefixes[] = {{"Async", "true", ", void* tag", ", tag"},
+                        {"PrepareAsync", "false", "", ", nullptr"}};
   if (method->NoStreaming()) {
     printer->Print(*vars,
                    "::grpc::Status $ns$$Service$::Stub::$Method$("
@@ -1087,19 +1189,23 @@ void PrintSourceClientMethod(grpc_generator::Printer *printer,
                    "rpcmethod_$Method$_, "
                    "context, request, response);\n"
                    "}\n\n");
-    printer->Print(
-        *vars,
-        "::grpc::ClientAsyncResponseReader< $Response$>* "
-        "$ns$$Service$::Stub::Async$Method$Raw(::grpc::ClientContext* context, "
-        "const $Request$& request, "
-        "::grpc::CompletionQueue* cq) {\n");
-    printer->Print(*vars,
-                   "  return "
-                   "::grpc::ClientAsyncResponseReader< $Response$>::Create("
-                   "channel_.get(), cq, "
-                   "rpcmethod_$Method$_, "
-                   "context, request);\n"
-                   "}\n\n");
+    for (auto async_prefix : async_prefixes) {
+      (*vars)["AsyncPrefix"] = async_prefix.prefix;
+      (*vars)["AsyncStart"] = async_prefix.start;
+      printer->Print(*vars,
+                     "::grpc::ClientAsyncResponseReader< $Response$>* "
+                     "$ns$$Service$::Stub::$AsyncPrefix$$Method$Raw(::grpc::"
+                     "ClientContext* context, "
+                     "const $Request$& request, "
+                     "::grpc::CompletionQueue* cq) {\n");
+      printer->Print(*vars,
+                     "  return "
+                     "::grpc::ClientAsyncResponseReader< $Response$>::Create("
+                     "channel_.get(), cq, "
+                     "rpcmethod_$Method$_, "
+                     "context, request, $AsyncStart$);\n"
+                     "}\n\n");
+    }
   } else if (ClientOnlyStreaming(method)) {
     printer->Print(*vars,
                    "::grpc::ClientWriter< $Request$>* "
@@ -1111,17 +1217,23 @@ void PrintSourceClientMethod(grpc_generator::Printer *printer,
                    "rpcmethod_$Method$_, "
                    "context, response);\n"
                    "}\n\n");
-    printer->Print(*vars,
-                   "::grpc::ClientAsyncWriter< $Request$>* "
-                   "$ns$$Service$::Stub::Async$Method$Raw("
-                   "::grpc::ClientContext* context, $Response$* response, "
-                   "::grpc::CompletionQueue* cq, void* tag) {\n");
-    printer->Print(*vars,
-                   "  return ::grpc::ClientAsyncWriter< $Request$>::Create("
-                   "channel_.get(), cq, "
-                   "rpcmethod_$Method$_, "
-                   "context, response, tag);\n"
-                   "}\n\n");
+    for (auto async_prefix : async_prefixes) {
+      (*vars)["AsyncPrefix"] = async_prefix.prefix;
+      (*vars)["AsyncStart"] = async_prefix.start;
+      (*vars)["AsyncMethodParams"] = async_prefix.method_params;
+      (*vars)["AsyncCreateArgs"] = async_prefix.create_args;
+      printer->Print(*vars,
+                     "::grpc::ClientAsyncWriter< $Request$>* "
+                     "$ns$$Service$::Stub::$AsyncPrefix$$Method$Raw("
+                     "::grpc::ClientContext* context, $Response$* response, "
+                     "::grpc::CompletionQueue* cq$AsyncMethodParams$) {\n");
+      printer->Print(*vars,
+                     "  return ::grpc::ClientAsyncWriter< $Request$>::Create("
+                     "channel_.get(), cq, "
+                     "rpcmethod_$Method$_, "
+                     "context, response, $AsyncStart$$AsyncCreateArgs$);\n"
+                     "}\n\n");
+    }
   } else if (ServerOnlyStreaming(method)) {
     printer->Print(
         *vars,
@@ -1134,17 +1246,24 @@ void PrintSourceClientMethod(grpc_generator::Printer *printer,
                    "rpcmethod_$Method$_, "
                    "context, request);\n"
                    "}\n\n");
-    printer->Print(*vars,
-                   "::grpc::ClientAsyncReader< $Response$>* "
-                   "$ns$$Service$::Stub::Async$Method$Raw("
-                   "::grpc::ClientContext* context, const $Request$& request, "
-                   "::grpc::CompletionQueue* cq, void* tag) {\n");
-    printer->Print(*vars,
-                   "  return ::grpc::ClientAsyncReader< $Response$>::Create("
-                   "channel_.get(), cq, "
-                   "rpcmethod_$Method$_, "
-                   "context, request, tag);\n"
-                   "}\n\n");
+    for (auto async_prefix : async_prefixes) {
+      (*vars)["AsyncPrefix"] = async_prefix.prefix;
+      (*vars)["AsyncStart"] = async_prefix.start;
+      (*vars)["AsyncMethodParams"] = async_prefix.method_params;
+      (*vars)["AsyncCreateArgs"] = async_prefix.create_args;
+      printer->Print(
+          *vars,
+          "::grpc::ClientAsyncReader< $Response$>* "
+          "$ns$$Service$::Stub::$AsyncPrefix$$Method$Raw("
+          "::grpc::ClientContext* context, const $Request$& request, "
+          "::grpc::CompletionQueue* cq$AsyncMethodParams$) {\n");
+      printer->Print(*vars,
+                     "  return ::grpc::ClientAsyncReader< $Response$>::Create("
+                     "channel_.get(), cq, "
+                     "rpcmethod_$Method$_, "
+                     "context, request, $AsyncStart$$AsyncCreateArgs$);\n"
+                     "}\n\n");
+    }
   } else if (method->BidiStreaming()) {
     printer->Print(
         *vars,
@@ -1157,19 +1276,25 @@ void PrintSourceClientMethod(grpc_generator::Printer *printer,
                    "rpcmethod_$Method$_, "
                    "context);\n"
                    "}\n\n");
-    printer->Print(
-        *vars,
-        "::grpc::ClientAsyncReaderWriter< $Request$, $Response$>* "
-        "$ns$$Service$::Stub::Async$Method$Raw(::grpc::ClientContext* context, "
-        "::grpc::CompletionQueue* cq, void* tag) {\n");
-    printer->Print(
-        *vars,
-        "  return "
-        "::grpc::ClientAsyncReaderWriter< $Request$, $Response$>::Create("
-        "channel_.get(), cq, "
-        "rpcmethod_$Method$_, "
-        "context, tag);\n"
-        "}\n\n");
+    for (auto async_prefix : async_prefixes) {
+      (*vars)["AsyncPrefix"] = async_prefix.prefix;
+      (*vars)["AsyncStart"] = async_prefix.start;
+      (*vars)["AsyncMethodParams"] = async_prefix.method_params;
+      (*vars)["AsyncCreateArgs"] = async_prefix.create_args;
+      printer->Print(*vars,
+                     "::grpc::ClientAsyncReaderWriter< $Request$, $Response$>* "
+                     "$ns$$Service$::Stub::$AsyncPrefix$$Method$Raw(::grpc::"
+                     "ClientContext* context, "
+                     "::grpc::CompletionQueue* cq$AsyncMethodParams$) {\n");
+      printer->Print(
+          *vars,
+          "  return "
+          "::grpc::ClientAsyncReaderWriter< $Request$, $Response$>::Create("
+          "channel_.get(), cq, "
+          "rpcmethod_$Method$_, "
+          "context, $AsyncStart$$AsyncCreateArgs$);\n"
+          "}\n\n");
+    }
   }
 }
 
@@ -1460,50 +1585,79 @@ void PrintMockClientMethods(grpc_generator::Printer *printer,
   (*vars)["Request"] = method->input_type_name();
   (*vars)["Response"] = method->output_type_name();
 
+  struct {
+    grpc::string prefix;
+    grpc::string method_params;  // extra arguments to method
+    int extra_method_param_count;
+  } async_prefixes[] = {{"Async", ", void* tag", 1}, {"PrepareAsync", "", 0}};
+
   if (method->NoStreaming()) {
     printer->Print(
         *vars,
         "MOCK_METHOD3($Method$, ::grpc::Status(::grpc::ClientContext* context, "
         "const $Request$& request, $Response$* response));\n");
-    printer->Print(*vars,
-                   "MOCK_METHOD3(Async$Method$Raw, "
-                   "::grpc::ClientAsyncResponseReaderInterface< $Response$>*"
-                   "(::grpc::ClientContext* context, const $Request$& request, "
-                   "::grpc::CompletionQueue* cq));\n");
+    for (auto async_prefix : async_prefixes) {
+      (*vars)["AsyncPrefix"] = async_prefix.prefix;
+      printer->Print(
+          *vars,
+          "MOCK_METHOD3($AsyncPrefix$$Method$Raw, "
+          "::grpc::ClientAsyncResponseReaderInterface< $Response$>*"
+          "(::grpc::ClientContext* context, const $Request$& request, "
+          "::grpc::CompletionQueue* cq));\n");
+    }
   } else if (ClientOnlyStreaming(method)) {
     printer->Print(
         *vars,
         "MOCK_METHOD2($Method$Raw, "
         "::grpc::ClientWriterInterface< $Request$>*"
         "(::grpc::ClientContext* context, $Response$* response));\n");
-    printer->Print(*vars,
-                   "MOCK_METHOD4(Async$Method$Raw, "
-                   "::grpc::ClientAsyncWriterInterface< $Request$>*"
-                   "(::grpc::ClientContext* context, $Response$* response, "
-                   "::grpc::CompletionQueue* cq, void* tag));\n");
+    for (auto async_prefix : async_prefixes) {
+      (*vars)["AsyncPrefix"] = async_prefix.prefix;
+      (*vars)["AsyncMethodParams"] = async_prefix.method_params;
+      (*vars)["MockArgs"] =
+          std::to_string(3 + async_prefix.extra_method_param_count);
+      printer->Print(*vars,
+                     "MOCK_METHOD$MockArgs$($AsyncPrefix$$Method$Raw, "
+                     "::grpc::ClientAsyncWriterInterface< $Request$>*"
+                     "(::grpc::ClientContext* context, $Response$* response, "
+                     "::grpc::CompletionQueue* cq$AsyncMethodParams$));\n");
+    }
   } else if (ServerOnlyStreaming(method)) {
     printer->Print(
         *vars,
         "MOCK_METHOD2($Method$Raw, "
         "::grpc::ClientReaderInterface< $Response$>*"
         "(::grpc::ClientContext* context, const $Request$& request));\n");
-    printer->Print(*vars,
-                   "MOCK_METHOD4(Async$Method$Raw, "
-                   "::grpc::ClientAsyncReaderInterface< $Response$>*"
-                   "(::grpc::ClientContext* context, const $Request$& request, "
-                   "::grpc::CompletionQueue* cq, void* tag));\n");
+    for (auto async_prefix : async_prefixes) {
+      (*vars)["AsyncPrefix"] = async_prefix.prefix;
+      (*vars)["AsyncMethodParams"] = async_prefix.method_params;
+      (*vars)["MockArgs"] =
+          std::to_string(3 + async_prefix.extra_method_param_count);
+      printer->Print(
+          *vars,
+          "MOCK_METHOD$MockArgs$($AsyncPrefix$$Method$Raw, "
+          "::grpc::ClientAsyncReaderInterface< $Response$>*"
+          "(::grpc::ClientContext* context, const $Request$& request, "
+          "::grpc::CompletionQueue* cq$AsyncMethodParams$));\n");
+    }
   } else if (method->BidiStreaming()) {
     printer->Print(
         *vars,
         "MOCK_METHOD1($Method$Raw, "
         "::grpc::ClientReaderWriterInterface< $Request$, $Response$>*"
         "(::grpc::ClientContext* context));\n");
-    printer->Print(
-        *vars,
-        "MOCK_METHOD3(Async$Method$Raw, "
-        "::grpc::ClientAsyncReaderWriterInterface<$Request$, $Response$>*"
-        "(::grpc::ClientContext* context, ::grpc::CompletionQueue* cq, "
-        "void* tag));\n");
+    for (auto async_prefix : async_prefixes) {
+      (*vars)["AsyncPrefix"] = async_prefix.prefix;
+      (*vars)["AsyncMethodParams"] = async_prefix.method_params;
+      (*vars)["MockArgs"] =
+          std::to_string(2 + async_prefix.extra_method_param_count);
+      printer->Print(
+          *vars,
+          "MOCK_METHOD$MockArgs$($AsyncPrefix$$Method$Raw, "
+          "::grpc::ClientAsyncReaderWriterInterface<$Request$, $Response$>*"
+          "(::grpc::ClientContext* context, ::grpc::CompletionQueue* cq"
+          "$AsyncMethodParams$));\n");
+    }
   }
 }
 
diff --git a/src/compiler/python_generator.cc b/src/compiler/python_generator.cc
index 31b177c28e..a60b528e3b 100644
--- a/src/compiler/python_generator.cc
+++ b/src/compiler/python_generator.cc
@@ -769,7 +769,7 @@ bool PythonGrpcGenerator::Generate(const FileDescriptor* file,
   PrivateGenerator generator(config_, &pbfile);
   if (parameter == "grpc_2_0") {
     return GenerateGrpc(context, generator, pb2_grpc_file_name, true);
-  } else if (parameter == "") {
+  } else if (parameter == "grpc_1_0" || parameter == "") {
     return GenerateGrpc(context, generator, pb2_grpc_file_name, true) &&
            GenerateGrpc(context, generator, pb2_file_name, false);
   } else {
diff --git a/src/core/ext/filters/client_channel/channel_connectivity.c b/src/core/ext/filters/client_channel/channel_connectivity.c
index e5f6fa76ae..3844b98021 100644
--- a/src/core/ext/filters/client_channel/channel_connectivity.c
+++ b/src/core/ext/filters/client_channel/channel_connectivity.c
@@ -86,7 +86,7 @@ static void delete_state_watcher(grpc_exec_ctx *exec_ctx, state_watcher *w) {
 
 static void finished_completion(grpc_exec_ctx *exec_ctx, void *pw,
                                 grpc_cq_completion *ignored) {
-  int delete = 0;
+  bool should_delete = false;
   state_watcher *w = (state_watcher *)pw;
   gpr_mu_lock(&w->mu);
   switch (w->phase) {
@@ -94,12 +94,12 @@ static void finished_completion(grpc_exec_ctx *exec_ctx, void *pw,
     case READY_TO_CALL_BACK:
       GPR_UNREACHABLE_CODE(return );
     case CALLING_BACK_AND_FINISHED:
-      delete = 1;
+      should_delete = true;
       break;
   }
   gpr_mu_unlock(&w->mu);
 
-  if (delete) {
+  if (should_delete) {
     delete_state_watcher(exec_ctx, w);
   }
 }
@@ -161,12 +161,12 @@ static void partly_done(grpc_exec_ctx *exec_ctx, state_watcher *w,
 
 static void watch_complete(grpc_exec_ctx *exec_ctx, void *pw,
                            grpc_error *error) {
-  partly_done(exec_ctx, pw, true, GRPC_ERROR_REF(error));
+  partly_done(exec_ctx, (state_watcher *)pw, true, GRPC_ERROR_REF(error));
 }
 
 static void timeout_complete(grpc_exec_ctx *exec_ctx, void *pw,
                              grpc_error *error) {
-  partly_done(exec_ctx, pw, false, GRPC_ERROR_REF(error));
+  partly_done(exec_ctx, (state_watcher *)pw, false, GRPC_ERROR_REF(error));
 }
 
 int grpc_channel_num_external_connectivity_watchers(grpc_channel *channel) {
diff --git a/src/core/ext/filters/client_channel/client_channel.c b/src/core/ext/filters/client_channel/client_channel.c
index e5f4a8a813..129d0f368b 100644
--- a/src/core/ext/filters/client_channel/client_channel.c
+++ b/src/core/ext/filters/client_channel/client_channel.c
@@ -85,7 +85,7 @@ static void method_parameters_unref(method_parameters *method_params) {
 }
 
 static void method_parameters_free(grpc_exec_ctx *exec_ctx, void *value) {
-  method_parameters_unref(value);
+  method_parameters_unref((method_parameters *)value);
 }
 
 static bool parse_wait_for_ready(grpc_json *field,
@@ -717,7 +717,8 @@ static grpc_error *cc_init_channel_elem(grpc_exec_ctx *exec_ctx,
     return GRPC_ERROR_CREATE_FROM_STATIC_STRING(
         "client channel factory arg must be a pointer");
   }
-  grpc_client_channel_factory_ref(arg->value.pointer.p);
+  grpc_client_channel_factory_ref(
+      (grpc_client_channel_factory *)arg->value.pointer.p);
   chand->client_channel_factory =
       (grpc_client_channel_factory *)arg->value.pointer.p;
   // Get server name to resolve, using proxy mapper if needed.
diff --git a/src/core/ext/filters/client_channel/client_channel_factory.c b/src/core/ext/filters/client_channel/client_channel_factory.c
index 7220a8639e..e8aa4cda29 100644
--- a/src/core/ext/filters/client_channel/client_channel_factory.c
+++ b/src/core/ext/filters/client_channel/client_channel_factory.c
@@ -43,14 +43,13 @@ grpc_channel* grpc_client_channel_factory_create_channel(
 }
 
 static void* factory_arg_copy(void* factory) {
-  grpc_client_channel_factory_ref(factory);
+  grpc_client_channel_factory_ref((grpc_client_channel_factory*)factory);
   return factory;
 }
 
 static void factory_arg_destroy(grpc_exec_ctx* exec_ctx, void* factory) {
-  // TODO(roth): Remove local exec_ctx when
-  // https://github.com/grpc/grpc/pull/8705 is merged.
-  grpc_client_channel_factory_unref(exec_ctx, factory);
+  grpc_client_channel_factory_unref(exec_ctx,
+                                    (grpc_client_channel_factory*)factory);
 }
 
 static int factory_arg_cmp(void* factory1, void* factory2) {
diff --git a/src/core/ext/filters/client_channel/lb_policy/grpclb/client_load_reporting_filter.c b/src/core/ext/filters/client_channel/lb_policy/grpclb/client_load_reporting_filter.c
index bd290464c8..7ad322902b 100644
--- a/src/core/ext/filters/client_channel/lb_policy/grpclb/client_load_reporting_filter.c
+++ b/src/core/ext/filters/client_channel/lb_policy/grpclb/client_load_reporting_filter.c
@@ -75,7 +75,8 @@ static grpc_error *init_call_elem(grpc_exec_ctx *exec_ctx,
   GPR_ASSERT(args->context != NULL);
   GPR_ASSERT(args->context[GRPC_GRPCLB_CLIENT_STATS].value != NULL);
   calld->client_stats = grpc_grpclb_client_stats_ref(
-      args->context[GRPC_GRPCLB_CLIENT_STATS].value);
+      (grpc_grpclb_client_stats *)args->context[GRPC_GRPCLB_CLIENT_STATS]
+          .value);
   // Record call started.
   grpc_grpclb_client_stats_add_call_started(calld->client_stats);
   return GRPC_ERROR_NONE;
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 18979829bd..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
@@ -101,6 +101,7 @@
 #include "src/core/ext/filters/client_channel/lb_policy_registry.h"
 #include "src/core/ext/filters/client_channel/parse_address.h"
 #include "src/core/ext/filters/client_channel/resolver/fake/fake_resolver.h"
+#include "src/core/ext/filters/client_channel/subchannel_index.h"
 #include "src/core/lib/channel/channel_args.h"
 #include "src/core/lib/channel/channel_stack.h"
 #include "src/core/lib/iomgr/combiner.h"
@@ -122,7 +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");
 
@@ -138,7 +138,7 @@ static grpc_error *initial_metadata_add_lb_token(
 }
 
 static void destroy_client_stats(void *arg) {
-  grpc_grpclb_client_stats_unref(arg);
+  grpc_grpclb_client_stats_unref((grpc_grpclb_client_stats *)arg);
 }
 
 typedef struct wrapped_rr_closure_arg {
@@ -286,7 +286,7 @@ static void add_pending_ping(pending_ping **root, grpc_closure *notify) {
  * glb_lb_policy
  */
 typedef struct rr_connectivity_data rr_connectivity_data;
-static const grpc_lb_policy_vtable glb_lb_policy_vtable;
+
 typedef struct glb_lb_policy {
   /** base policy: must be first */
   grpc_lb_policy base;
@@ -299,10 +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;
 
@@ -329,9 +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;
 
@@ -352,9 +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;
 
@@ -377,9 +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 */
@@ -403,9 +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;
 
@@ -552,32 +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) {
@@ -645,38 +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(
@@ -714,18 +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;
@@ -783,7 +728,7 @@ static void create_rr_locked(grpc_exec_ctx *exec_ctx, glb_lb_policy *glb_policy,
   /* Allocate the data for the tracking of the new RR policy's connectivity.
    * It'll be deallocated in glb_rr_connectivity_changed() */
   rr_connectivity_data *rr_connectivity =
-      gpr_zalloc(sizeof(rr_connectivity_data));
+      (rr_connectivity_data *)gpr_zalloc(sizeof(rr_connectivity_data));
   GRPC_CLOSURE_INIT(&rr_connectivity->on_change,
                     glb_rr_connectivity_changed_locked, rr_connectivity,
                     grpc_combiner_scheduler(glb_policy->base.combiner));
@@ -831,6 +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);
@@ -923,7 +870,8 @@ static grpc_channel_args *build_lb_channel_args(
   grpc_lb_addresses *lb_addresses =
       grpc_lb_addresses_create(num_grpclb_addrs, NULL);
   grpc_slice_hash_table_entry *targets_info_entries =
-      gpr_zalloc(sizeof(*targets_info_entries) * num_grpclb_addrs);
+      (grpc_slice_hash_table_entry *)gpr_zalloc(sizeof(*targets_info_entries) *
+                                                num_grpclb_addrs);
 
   size_t lb_addresses_idx = 0;
   for (size_t i = 0; i < addresses->num_addresses; ++i) {
@@ -965,96 +913,6 @@ static grpc_channel_args *build_lb_channel_args(
   return result;
 }
 
-static void glb_lb_channel_on_connectivity_changed_cb(grpc_exec_ctx *exec_ctx,
-                                                      void *arg,
-                                                      grpc_error *error);
-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. */
-  const grpc_arg *arg =
-      grpc_channel_args_find(args->args, GRPC_ARG_LB_ADDRESSES);
-  if (arg == NULL || arg->type != GRPC_ARG_POINTER) {
-    return NULL;
-  }
-  grpc_lb_addresses *addresses = (grpc_lb_addresses *)arg->value.pointer.p;
-  size_t num_grpclb_addrs = 0;
-  for (size_t i = 0; i < addresses->num_addresses; ++i) {
-    if (addresses->addresses[i].is_balancer) ++num_grpclb_addrs;
-  }
-  if (num_grpclb_addrs == 0) return NULL;
-
-  glb_lb_policy *glb_policy = (glb_lb_policy *)gpr_zalloc(sizeof(*glb_policy));
-
-  /* Get server name. */
-  arg = grpc_channel_args_find(args->args, GRPC_ARG_SERVER_URI);
-  GPR_ASSERT(arg != NULL);
-  GPR_ASSERT(arg->type == GRPC_ARG_STRING);
-  grpc_uri *uri = grpc_uri_parse(exec_ctx, arg->value.string, true);
-  GPR_ASSERT(uri->path[0] != '\0');
-  glb_policy->server_name =
-      gpr_strdup(uri->path[0] == '/' ? uri->path + 1 : uri->path);
-  if (GRPC_TRACER_ON(grpc_lb_glb_trace)) {
-    gpr_log(GPR_INFO, "Will use '%s' as the server name for LB request.",
-            glb_policy->server_name);
-  }
-  grpc_uri_destroy(uri);
-
-  glb_policy->cc_factory = args->client_channel_factory;
-  GPR_ASSERT(glb_policy->cc_factory != NULL);
-
-  arg = grpc_channel_args_find(args->args, GRPC_ARG_GRPCLB_CALL_TIMEOUT_MS);
-  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 =
-      grpc_channel_arg_string_create(GRPC_ARG_LB_POLICY_NAME, "grpclb");
-  static const char *args_to_remove[] = {GRPC_ARG_LB_POLICY_NAME};
-  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();
-  grpc_channel_args *lb_channel_args = build_lb_channel_args(
-      exec_ctx, addresses, glb_policy->response_generator, args->args);
-  char *uri_str;
-  gpr_asprintf(&uri_str, "fake:///%s", glb_policy->server_name);
-  glb_policy->lb_channel = grpc_lb_policy_grpclb_create_lb_channel(
-      exec_ctx, uri_str, args->client_channel_factory, lb_channel_args);
-
-  /* Propagate initial resolution */
-  grpc_fake_resolver_response_generator_set_response(
-      exec_ctx, glb_policy->response_generator, lb_channel_args);
-  grpc_channel_args_destroy(exec_ctx, lb_channel_args);
-  gpr_free(uri_str);
-  if (glb_policy->lb_channel == NULL) {
-    gpr_free((void *)glb_policy->server_name);
-    grpc_channel_args_destroy(exec_ctx, glb_policy->args);
-    gpr_free(glb_policy);
-    return NULL;
-  }
-  GRPC_CLOSURE_INIT(&glb_policy->lb_channel_on_connectivity_changed,
-                    glb_lb_channel_on_connectivity_changed_cb, glb_policy,
-                    grpc_combiner_scheduler(args->combiner));
-  grpc_lb_policy_init(&glb_policy->base, &glb_lb_policy_vtable, args->combiner);
-  grpc_connectivity_state_init(&glb_policy->state_tracker, GRPC_CHANNEL_IDLE,
-                               "grpclb");
-  return &glb_policy->base;
-}
-
 static void glb_destroy(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol) {
   glb_lb_policy *glb_policy = (glb_lb_policy *)pol;
   GPR_ASSERT(glb_policy->pending_picks == NULL);
@@ -1068,10 +926,8 @@ 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) {
     grpc_channel_args_destroy(exec_ctx, glb_policy->pending_update_args->args);
     gpr_free(glb_policy->pending_update_args);
@@ -1211,28 +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);
@@ -1382,7 +1220,8 @@ static void do_send_client_load_report_locked(grpc_exec_ctx *exec_ctx,
 
 static bool load_report_counters_are_zero(grpc_grpclb_request *request) {
   grpc_grpclb_dropped_call_counts *drop_entries =
-      request->client_stats.calls_finished_with_drop.arg;
+      (grpc_grpclb_dropped_call_counts *)
+          request->client_stats.calls_finished_with_drop.arg;
   return request->client_stats.num_calls_started == 0 &&
          request->client_stats.num_calls_finished == 0 &&
          request->client_stats.num_calls_finished_with_client_failed_to_send ==
@@ -1686,15 +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
@@ -1705,7 +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);
         }
@@ -1752,26 +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 = 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;
@@ -1892,17 +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
@@ -1982,6 +1783,90 @@ static const grpc_lb_policy_vtable glb_lb_policy_vtable = {
     glb_notify_on_state_change_locked,
     glb_update_locked};
 
+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.
+   * 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) {
+    return NULL;
+  }
+  grpc_lb_addresses *addresses = (grpc_lb_addresses *)arg->value.pointer.p;
+  size_t num_grpclb_addrs = 0;
+  for (size_t i = 0; i < addresses->num_addresses; ++i) {
+    if (addresses->addresses[i].is_balancer) ++num_grpclb_addrs;
+  }
+  if (num_grpclb_addrs == 0) return NULL;
+
+  glb_lb_policy *glb_policy = (glb_lb_policy *)gpr_zalloc(sizeof(*glb_policy));
+
+  /* Get server name. */
+  arg = grpc_channel_args_find(args->args, GRPC_ARG_SERVER_URI);
+  GPR_ASSERT(arg != NULL);
+  GPR_ASSERT(arg->type == GRPC_ARG_STRING);
+  grpc_uri *uri = grpc_uri_parse(exec_ctx, arg->value.string, true);
+  GPR_ASSERT(uri->path[0] != '\0');
+  glb_policy->server_name =
+      gpr_strdup(uri->path[0] == '/' ? uri->path + 1 : uri->path);
+  if (GRPC_TRACER_ON(grpc_lb_glb_trace)) {
+    gpr_log(GPR_INFO, "Will use '%s' as the server name for LB request.",
+            glb_policy->server_name);
+  }
+  grpc_uri_destroy(uri);
+
+  glb_policy->cc_factory = args->client_channel_factory;
+  GPR_ASSERT(glb_policy->cc_factory != NULL);
+
+  arg = grpc_channel_args_find(args->args, GRPC_ARG_GRPCLB_CALL_TIMEOUT_MS);
+  glb_policy->lb_call_timeout_ms =
+      grpc_channel_arg_get_integer(arg, (grpc_integer_options){0, 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 =
+      grpc_channel_arg_string_create(GRPC_ARG_LB_POLICY_NAME, "grpclb");
+  static const char *args_to_remove[] = {GRPC_ARG_LB_POLICY_NAME};
+  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);
+
+  /* Create a client channel over them to communicate with a LB service */
+  glb_policy->response_generator =
+      grpc_fake_resolver_response_generator_create();
+  grpc_channel_args *lb_channel_args = build_lb_channel_args(
+      exec_ctx, addresses, glb_policy->response_generator, args->args);
+  char *uri_str;
+  gpr_asprintf(&uri_str, "fake:///%s", glb_policy->server_name);
+  glb_policy->lb_channel = grpc_lb_policy_grpclb_create_lb_channel(
+      exec_ctx, uri_str, args->client_channel_factory, lb_channel_args);
+
+  /* Propagate initial resolution */
+  grpc_fake_resolver_response_generator_set_response(
+      exec_ctx, glb_policy->response_generator, lb_channel_args);
+  grpc_channel_args_destroy(exec_ctx, lb_channel_args);
+  gpr_free(uri_str);
+  if (glb_policy->lb_channel == NULL) {
+    gpr_free((void *)glb_policy->server_name);
+    grpc_channel_args_destroy(exec_ctx, glb_policy->args);
+    gpr_free(glb_policy);
+    return NULL;
+  }
+  grpc_subchannel_index_ref();
+  GRPC_CLOSURE_INIT(&glb_policy->lb_channel_on_connectivity_changed,
+                    glb_lb_channel_on_connectivity_changed_cb, glb_policy,
+                    grpc_combiner_scheduler(args->combiner));
+  grpc_lb_policy_init(&glb_policy->base, &glb_lb_policy_vtable, args->combiner);
+  grpc_connectivity_state_init(&glb_policy->state_tracker, GRPC_CHANNEL_IDLE,
+                               "grpclb");
+  return &glb_policy->base;
+}
+
 static void glb_factory_ref(grpc_lb_policy_factory *factory) {}
 
 static void glb_factory_unref(grpc_lb_policy_factory *factory) {}
diff --git a/src/core/ext/filters/client_channel/lb_policy/grpclb/load_balancer_api.c b/src/core/ext/filters/client_channel/lb_policy/grpclb/load_balancer_api.c
index 407bd18adb..8ef6dfc6f4 100644
--- a/src/core/ext/filters/client_channel/lb_policy/grpclb/load_balancer_api.c
+++ b/src/core/ext/filters/client_channel/lb_policy/grpclb/load_balancer_api.c
@@ -148,7 +148,8 @@ grpc_slice grpc_grpclb_request_encode(const grpc_grpclb_request *request) {
 void grpc_grpclb_request_destroy(grpc_grpclb_request *request) {
   if (request->has_client_stats) {
     grpc_grpclb_dropped_call_counts *drop_entries =
-        request->client_stats.calls_finished_with_drop.arg;
+        (grpc_grpclb_dropped_call_counts *)
+            request->client_stats.calls_finished_with_drop.arg;
     grpc_grpclb_dropped_call_counts_destroy(drop_entries);
   }
   gpr_free(request);
@@ -170,7 +171,8 @@ grpc_grpclb_initial_response *grpc_grpclb_initial_response_parse(
   if (!res.has_initial_response) return NULL;
 
   grpc_grpclb_initial_response *initial_res =
-      gpr_malloc(sizeof(grpc_grpclb_initial_response));
+      (grpc_grpclb_initial_response *)gpr_malloc(
+          sizeof(grpc_grpclb_initial_response));
   memcpy(initial_res, &res.initial_response,
          sizeof(grpc_grpclb_initial_response));
 
diff --git a/src/core/ext/filters/client_channel/lb_policy/pick_first/pick_first.c b/src/core/ext/filters/client_channel/lb_policy/pick_first/pick_first.c
index fab3073eb9..d20cbb8388 100644
--- a/src/core/ext/filters/client_channel/lb_policy/pick_first/pick_first.c
+++ b/src/core/ext/filters/client_channel/lb_policy/pick_first/pick_first.c
@@ -89,6 +89,7 @@ static void pf_destroy(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol) {
                                     "picked_first_destroy");
   }
   grpc_connectivity_state_destroy(exec_ctx, &p->state_tracker);
+  grpc_subchannel_index_unref();
   if (p->pending_update_args != NULL) {
     grpc_channel_args_destroy(exec_ctx, p->pending_update_args->args);
     gpr_free(p->pending_update_args);
@@ -330,8 +331,8 @@ static void pf_update_locked(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,
     gpr_log(GPR_INFO, "Pick First %p received update with %lu addresses",
             (void *)p, (unsigned long)addresses->num_addresses);
   }
-  grpc_subchannel_args *sc_args =
-      gpr_zalloc(sizeof(*sc_args) * addresses->num_addresses);
+  grpc_subchannel_args *sc_args = (grpc_subchannel_args *)gpr_zalloc(
+      sizeof(*sc_args) * addresses->num_addresses);
   /* We remove the following keys in order for subchannel keys belonging to
    * subchannels point to the same address to match. */
   static const char *keys_to_remove[] = {GRPC_ARG_SUBCHANNEL_ADDRESS,
@@ -403,7 +404,7 @@ static void pf_update_locked(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,
   }
   /* Create the subchannels for the new subchannel args/addresses. */
   grpc_subchannel **new_subchannels =
-      gpr_zalloc(sizeof(*new_subchannels) * sc_args_count);
+      (grpc_subchannel **)gpr_zalloc(sizeof(*new_subchannels) * sc_args_count);
   size_t num_new_subchannels = 0;
   for (size_t i = 0; i < sc_args_count; i++) {
     grpc_subchannel *subchannel = grpc_client_channel_factory_create_subchannel(
@@ -686,6 +687,7 @@ static grpc_lb_policy *create_pick_first(grpc_exec_ctx *exec_ctx,
   }
   pf_update_locked(exec_ctx, &p->base, args);
   grpc_lb_policy_init(&p->base, &pick_first_lb_policy_vtable, args->combiner);
+  grpc_subchannel_index_ref();
   GRPC_CLOSURE_INIT(&p->connectivity_changed, pf_connectivity_changed_locked, p,
                     grpc_combiner_scheduler(args->combiner));
   return &p->base;
diff --git a/src/core/ext/filters/client_channel/lb_policy/round_robin/round_robin.c b/src/core/ext/filters/client_channel/lb_policy/round_robin/round_robin.c
index be91d3d651..8ac1a46abd 100644
--- a/src/core/ext/filters/client_channel/lb_policy/round_robin/round_robin.c
+++ b/src/core/ext/filters/client_channel/lb_policy/round_robin/round_robin.c
@@ -30,6 +30,7 @@
 
 #include "src/core/ext/filters/client_channel/lb_policy_registry.h"
 #include "src/core/ext/filters/client_channel/subchannel.h"
+#include "src/core/ext/filters/client_channel/subchannel_index.h"
 #include "src/core/lib/channel/channel_args.h"
 #include "src/core/lib/debug/trace.h"
 #include "src/core/lib/iomgr/combiner.h"
@@ -310,6 +311,7 @@ static void rr_destroy(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol) {
             (void *)pol, (void *)pol);
   }
   grpc_connectivity_state_destroy(exec_ctx, &p->state_tracker);
+  grpc_subchannel_index_unref();
   gpr_free(p);
 }
 
@@ -890,6 +892,7 @@ static grpc_lb_policy *round_robin_create(grpc_exec_ctx *exec_ctx,
   GPR_ASSERT(args->client_channel_factory != NULL);
   round_robin_lb_policy *p = (round_robin_lb_policy *)gpr_zalloc(sizeof(*p));
   grpc_lb_policy_init(&p->base, &round_robin_lb_policy_vtable, args->combiner);
+  grpc_subchannel_index_ref();
   grpc_connectivity_state_init(&p->state_tracker, GRPC_CHANNEL_IDLE,
                                "round_robin");
   rr_update_locked(exec_ctx, &p->base, args);
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 918bab745c..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);
@@ -126,13 +126,14 @@ void grpc_lb_addresses_destroy(grpc_exec_ctx* exec_ctx,
 }
 
 static void* lb_addresses_copy(void* addresses) {
-  return grpc_lb_addresses_copy(addresses);
+  return grpc_lb_addresses_copy((grpc_lb_addresses*)addresses);
 }
 static void lb_addresses_destroy(grpc_exec_ctx* exec_ctx, void* addresses) {
-  grpc_lb_addresses_destroy(exec_ctx, addresses);
+  grpc_lb_addresses_destroy(exec_ctx, (grpc_lb_addresses*)addresses);
 }
 static int lb_addresses_cmp(void* addresses1, void* addresses2) {
-  return grpc_lb_addresses_cmp(addresses1, addresses2);
+  return grpc_lb_addresses_cmp((grpc_lb_addresses*)addresses1,
+                               (grpc_lb_addresses*)addresses2);
 }
 static const grpc_arg_pointer_vtable lb_addresses_arg_vtable = {
     lb_addresses_copy, lb_addresses_destroy, lb_addresses_cmp};
@@ -149,7 +150,7 @@ grpc_lb_addresses* grpc_lb_addresses_find_channel_arg(
       grpc_channel_args_find(channel_args, GRPC_ARG_LB_ADDRESSES);
   if (lb_addresses_arg == NULL || lb_addresses_arg->type != GRPC_ARG_POINTER)
     return NULL;
-  return lb_addresses_arg->value.pointer.p;
+  return (grpc_lb_addresses*)lb_addresses_arg->value.pointer.p;
 }
 
 void grpc_lb_policy_factory_ref(grpc_lb_policy_factory* factory) {
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/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_posix.c b/src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_posix.c
index 9747d39a16..7f1f57259a 100644
--- a/src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_posix.c
+++ b/src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_posix.c
@@ -38,7 +38,7 @@ typedef struct fd_node {
   /** the owner of this fd node */
   grpc_ares_ev_driver *ev_driver;
   /** the grpc_fd owned by this fd node */
-  grpc_fd *grpc_fd;
+  grpc_fd *fd;
   /** a closure wrapping on_readable_cb, which should be invoked when the
       grpc_fd in this node becomes readable. */
   grpc_closure read_closure;
@@ -96,15 +96,15 @@ static void grpc_ares_ev_driver_unref(grpc_ares_ev_driver *ev_driver) {
 }
 
 static void fd_node_destroy(grpc_exec_ctx *exec_ctx, fd_node *fdn) {
-  gpr_log(GPR_DEBUG, "delete fd: %d", grpc_fd_wrapped_fd(fdn->grpc_fd));
+  gpr_log(GPR_DEBUG, "delete fd: %d", grpc_fd_wrapped_fd(fdn->fd));
   GPR_ASSERT(!fdn->readable_registered);
   GPR_ASSERT(!fdn->writable_registered);
   gpr_mu_destroy(&fdn->mu);
-  grpc_pollset_set_del_fd(exec_ctx, fdn->ev_driver->pollset_set, fdn->grpc_fd);
+  grpc_pollset_set_del_fd(exec_ctx, fdn->ev_driver->pollset_set, fdn->fd);
   /* c-ares library has closed the fd inside grpc_fd. This fd may be picked up
      immediately by another thread, and should not be closed by the following
      grpc_fd_orphan. */
-  grpc_fd_orphan(exec_ctx, fdn->grpc_fd, NULL, NULL, true /* already_closed */,
+  grpc_fd_orphan(exec_ctx, fdn->fd, NULL, NULL, true /* already_closed */,
                  "c-ares query finished");
   gpr_free(fdn);
 }
@@ -150,9 +150,8 @@ void grpc_ares_ev_driver_shutdown(grpc_exec_ctx *exec_ctx,
   ev_driver->shutting_down = true;
   fd_node *fn = ev_driver->fds;
   while (fn != NULL) {
-    grpc_fd_shutdown(
-        exec_ctx, fn->grpc_fd,
-        GRPC_ERROR_CREATE_FROM_STATIC_STRING("grpc_ares_ev_driver_shutdown"));
+    grpc_fd_shutdown(exec_ctx, fn->fd, GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+                                           "grpc_ares_ev_driver_shutdown"));
     fn = fn->next;
   }
   gpr_mu_unlock(&ev_driver->mu);
@@ -165,7 +164,7 @@ static fd_node *pop_fd_node(fd_node **head, int fd) {
   dummy_head.next = *head;
   fd_node *node = &dummy_head;
   while (node->next != NULL) {
-    if (grpc_fd_wrapped_fd(node->next->grpc_fd) == fd) {
+    if (grpc_fd_wrapped_fd(node->next->fd) == fd) {
       fd_node *ret = node->next;
       node->next = node->next->next;
       *head = dummy_head.next;
@@ -184,9 +183,9 @@ static void on_readable_cb(grpc_exec_ctx *exec_ctx, void *arg,
   fdn->readable_registered = false;
   gpr_mu_unlock(&fdn->mu);
 
-  gpr_log(GPR_DEBUG, "readable on %d", grpc_fd_wrapped_fd(fdn->grpc_fd));
+  gpr_log(GPR_DEBUG, "readable on %d", grpc_fd_wrapped_fd(fdn->fd));
   if (error == GRPC_ERROR_NONE) {
-    ares_process_fd(ev_driver->channel, grpc_fd_wrapped_fd(fdn->grpc_fd),
+    ares_process_fd(ev_driver->channel, grpc_fd_wrapped_fd(fdn->fd),
                     ARES_SOCKET_BAD);
   } else {
     // If error is not GRPC_ERROR_NONE, it means the fd has been shutdown or
@@ -211,10 +210,10 @@ static void on_writable_cb(grpc_exec_ctx *exec_ctx, void *arg,
   fdn->writable_registered = false;
   gpr_mu_unlock(&fdn->mu);
 
-  gpr_log(GPR_DEBUG, "writable on %d", grpc_fd_wrapped_fd(fdn->grpc_fd));
+  gpr_log(GPR_DEBUG, "writable on %d", grpc_fd_wrapped_fd(fdn->fd));
   if (error == GRPC_ERROR_NONE) {
     ares_process_fd(ev_driver->channel, ARES_SOCKET_BAD,
-                    grpc_fd_wrapped_fd(fdn->grpc_fd));
+                    grpc_fd_wrapped_fd(fdn->fd));
   } else {
     // If error is not GRPC_ERROR_NONE, it means the fd has been shutdown or
     // timed out. The pending lookups made on this ev_driver will be cancelled
@@ -253,7 +252,7 @@ static void grpc_ares_notify_on_event_locked(grpc_exec_ctx *exec_ctx,
           gpr_asprintf(&fd_name, "ares_ev_driver-%" PRIuPTR, i);
           fdn = (fd_node *)gpr_malloc(sizeof(fd_node));
           gpr_log(GPR_DEBUG, "new fd: %d", socks[i]);
-          fdn->grpc_fd = grpc_fd_create(socks[i], fd_name);
+          fdn->fd = grpc_fd_create(socks[i], fd_name);
           fdn->ev_driver = ev_driver;
           fdn->readable_registered = false;
           fdn->writable_registered = false;
@@ -262,8 +261,7 @@ static void grpc_ares_notify_on_event_locked(grpc_exec_ctx *exec_ctx,
                             grpc_schedule_on_exec_ctx);
           GRPC_CLOSURE_INIT(&fdn->write_closure, on_writable_cb, fdn,
                             grpc_schedule_on_exec_ctx);
-          grpc_pollset_set_add_fd(exec_ctx, ev_driver->pollset_set,
-                                  fdn->grpc_fd);
+          grpc_pollset_set_add_fd(exec_ctx, ev_driver->pollset_set, fdn->fd);
           gpr_free(fd_name);
         }
         fdn->next = new_list;
@@ -274,9 +272,8 @@ static void grpc_ares_notify_on_event_locked(grpc_exec_ctx *exec_ctx,
         if (ARES_GETSOCK_READABLE(socks_bitmask, i) &&
             !fdn->readable_registered) {
           grpc_ares_ev_driver_ref(ev_driver);
-          gpr_log(GPR_DEBUG, "notify read on: %d",
-                  grpc_fd_wrapped_fd(fdn->grpc_fd));
-          grpc_fd_notify_on_read(exec_ctx, fdn->grpc_fd, &fdn->read_closure);
+          gpr_log(GPR_DEBUG, "notify read on: %d", grpc_fd_wrapped_fd(fdn->fd));
+          grpc_fd_notify_on_read(exec_ctx, fdn->fd, &fdn->read_closure);
           fdn->readable_registered = true;
         }
         // Register write_closure if the socket is writable and write_closure
@@ -284,9 +281,9 @@ static void grpc_ares_notify_on_event_locked(grpc_exec_ctx *exec_ctx,
         if (ARES_GETSOCK_WRITABLE(socks_bitmask, i) &&
             !fdn->writable_registered) {
           gpr_log(GPR_DEBUG, "notify write on: %d",
-                  grpc_fd_wrapped_fd(fdn->grpc_fd));
+                  grpc_fd_wrapped_fd(fdn->fd));
           grpc_ares_ev_driver_ref(ev_driver);
-          grpc_fd_notify_on_write(exec_ctx, fdn->grpc_fd, &fdn->write_closure);
+          grpc_fd_notify_on_write(exec_ctx, fdn->fd, &fdn->write_closure);
           fdn->writable_registered = true;
         }
         gpr_mu_unlock(&fdn->mu);
diff --git a/src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.c b/src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.c
index 2e2b411ab8..0ffb38518a 100644
--- a/src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.c
+++ b/src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.c
@@ -123,8 +123,8 @@ static void grpc_ares_request_unref(grpc_exec_ctx *exec_ctx,
 static grpc_ares_hostbyname_request *create_hostbyname_request(
     grpc_ares_request *parent_request, char *host, uint16_t port,
     bool is_balancer) {
-  grpc_ares_hostbyname_request *hr =
-      gpr_zalloc(sizeof(grpc_ares_hostbyname_request));
+  grpc_ares_hostbyname_request *hr = (grpc_ares_hostbyname_request *)gpr_zalloc(
+      sizeof(grpc_ares_hostbyname_request));
   hr->parent_request = parent_request;
   hr->host = gpr_strdup(host);
   hr->port = port;
@@ -527,7 +527,8 @@ static void grpc_resolve_address_ares_impl(grpc_exec_ctx *exec_ctx,
                                            grpc_closure *on_done,
                                            grpc_resolved_addresses **addrs) {
   grpc_resolve_address_ares_request *r =
-      gpr_zalloc(sizeof(grpc_resolve_address_ares_request));
+      (grpc_resolve_address_ares_request *)gpr_zalloc(
+          sizeof(grpc_resolve_address_ares_request));
   r->addrs_out = addrs;
   r->on_resolve_address_done = on_done;
   GRPC_CLOSURE_INIT(&r->on_dns_lookup_done, on_dns_lookup_done_cb, r,
diff --git a/src/core/ext/filters/client_channel/retry_throttle.c b/src/core/ext/filters/client_channel/retry_throttle.c
index 6cd6654b6f..09dcade089 100644
--- a/src/core/ext/filters/client_channel/retry_throttle.c
+++ b/src/core/ext/filters/client_channel/retry_throttle.c
@@ -99,7 +99,7 @@ static grpc_server_retry_throttle_data* grpc_server_retry_throttle_data_create(
     int max_milli_tokens, int milli_token_ratio,
     grpc_server_retry_throttle_data* old_throttle_data) {
   grpc_server_retry_throttle_data* throttle_data =
-      gpr_malloc(sizeof(*throttle_data));
+      (grpc_server_retry_throttle_data*)gpr_malloc(sizeof(*throttle_data));
   memset(throttle_data, 0, sizeof(*throttle_data));
   gpr_ref_init(&throttle_data->refs, 1);
   throttle_data->max_milli_tokens = max_milli_tokens;
@@ -131,11 +131,11 @@ static grpc_server_retry_throttle_data* grpc_server_retry_throttle_data_create(
 //
 
 static void* copy_server_name(void* key, void* unused) {
-  return gpr_strdup(key);
+  return gpr_strdup((const char*)key);
 }
 
 static long compare_server_name(void* key1, void* key2, void* unused) {
-  return strcmp(key1, key2);
+  return strcmp((const char*)key1, (const char*)key2);
 }
 
 static void destroy_server_retry_throttle_data(void* value, void* unused) {
@@ -177,7 +177,8 @@ grpc_server_retry_throttle_data* grpc_retry_throttle_map_get_data_for_server(
     const char* server_name, int max_milli_tokens, int milli_token_ratio) {
   gpr_mu_lock(&g_mu);
   grpc_server_retry_throttle_data* throttle_data =
-      gpr_avl_get(g_avl, (char*)server_name, NULL);
+      (grpc_server_retry_throttle_data*)gpr_avl_get(g_avl, (char*)server_name,
+                                                    NULL);
   if (throttle_data == NULL) {
     // Entry not found.  Create a new one.
     throttle_data = grpc_server_retry_throttle_data_create(
diff --git a/src/core/ext/filters/client_channel/subchannel.c b/src/core/ext/filters/client_channel/subchannel.c
index 05c55aaa89..bc9c3cc782 100644
--- a/src/core/ext/filters/client_channel/subchannel.c
+++ b/src/core/ext/filters/client_channel/subchannel.c
@@ -32,6 +32,7 @@
 #include "src/core/ext/filters/client_channel/uri_parser.h"
 #include "src/core/lib/channel/channel_args.h"
 #include "src/core/lib/channel/connected_channel.h"
+#include "src/core/lib/debug/stats.h"
 #include "src/core/lib/iomgr/sockaddr_utils.h"
 #include "src/core/lib/iomgr/timer.h"
 #include "src/core/lib/profiling/timers.h"
@@ -290,6 +291,7 @@ grpc_subchannel *grpc_subchannel_create(grpc_exec_ctx *exec_ctx,
     return c;
   }
 
+  GRPC_STATS_INC_CLIENT_SUBCHANNELS_CREATED(exec_ctx);
   c = (grpc_subchannel *)gpr_zalloc(sizeof(*c));
   c->key = key;
   gpr_atm_no_barrier_store(&c->ref_pair, 1 << INTERNAL_REF_BITS);
diff --git a/src/core/ext/filters/client_channel/subchannel_index.c b/src/core/ext/filters/client_channel/subchannel_index.c
index f57b631c41..d7a51f3899 100644
--- a/src/core/ext/filters/client_channel/subchannel_index.c
+++ b/src/core/ext/filters/client_channel/subchannel_index.c
@@ -34,6 +34,8 @@ static gpr_avl g_subchannel_index;
 
 static gpr_mu g_mu;
 
+static gpr_refcount g_refcount;
+
 struct grpc_subchannel_key {
   grpc_subchannel_args args;
 };
@@ -88,24 +90,26 @@ void grpc_subchannel_key_destroy(grpc_exec_ctx *exec_ctx,
 
 static void sck_avl_destroy(void *p, void *user_data) {
   grpc_exec_ctx *exec_ctx = (grpc_exec_ctx *)user_data;
-  grpc_subchannel_key_destroy(exec_ctx, p);
+  grpc_subchannel_key_destroy(exec_ctx, (grpc_subchannel_key *)p);
 }
 
 static void *sck_avl_copy(void *p, void *unused) {
-  return subchannel_key_copy(p);
+  return subchannel_key_copy((grpc_subchannel_key *)p);
 }
 
 static long sck_avl_compare(void *a, void *b, void *unused) {
-  return grpc_subchannel_key_compare(a, b);
+  return grpc_subchannel_key_compare((grpc_subchannel_key *)a,
+                                     (grpc_subchannel_key *)b);
 }
 
 static void scv_avl_destroy(void *p, void *user_data) {
   grpc_exec_ctx *exec_ctx = (grpc_exec_ctx *)user_data;
-  GRPC_SUBCHANNEL_WEAK_UNREF(exec_ctx, p, "subchannel_index");
+  GRPC_SUBCHANNEL_WEAK_UNREF(exec_ctx, (grpc_subchannel *)p,
+                             "subchannel_index");
 }
 
 static void *scv_avl_copy(void *p, void *unused) {
-  GRPC_SUBCHANNEL_WEAK_REF(p, "subchannel_index");
+  GRPC_SUBCHANNEL_WEAK_REF((grpc_subchannel *)p, "subchannel_index");
   return p;
 }
 
@@ -119,15 +123,27 @@ static const gpr_avl_vtable subchannel_avl_vtable = {
 void grpc_subchannel_index_init(void) {
   g_subchannel_index = gpr_avl_create(&subchannel_avl_vtable);
   gpr_mu_init(&g_mu);
+  gpr_ref_init(&g_refcount, 1);
 }
 
 void grpc_subchannel_index_shutdown(void) {
-  grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
-  gpr_mu_destroy(&g_mu);
-  gpr_avl_unref(g_subchannel_index, &exec_ctx);
-  grpc_exec_ctx_finish(&exec_ctx);
+  // TODO(juanlishen): This refcounting mechanism may lead to memory leackage.
+  // To solve that, we should force polling to flush any pending callbacks, then
+  // shutdown safely.
+  grpc_subchannel_index_unref();
+}
+
+void grpc_subchannel_index_unref(void) {
+  if (gpr_unref(&g_refcount)) {
+    grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
+    gpr_mu_destroy(&g_mu);
+    gpr_avl_unref(g_subchannel_index, &exec_ctx);
+    grpc_exec_ctx_finish(&exec_ctx);
+  }
 }
 
+void grpc_subchannel_index_ref(void) { gpr_ref_non_zero(&g_refcount); }
+
 grpc_subchannel *grpc_subchannel_index_find(grpc_exec_ctx *exec_ctx,
                                             grpc_subchannel_key *key) {
   // Lock, and take a reference to the subchannel index.
diff --git a/src/core/ext/filters/client_channel/subchannel_index.h b/src/core/ext/filters/client_channel/subchannel_index.h
index 98d882a453..92e36d5283 100644
--- a/src/core/ext/filters/client_channel/subchannel_index.h
+++ b/src/core/ext/filters/client_channel/subchannel_index.h
@@ -59,6 +59,13 @@ void grpc_subchannel_index_init(void);
 /** Shutdown the subchannel index (global) */
 void grpc_subchannel_index_shutdown(void);
 
+/** Increment the refcount (non-zero) of subchannel index (global). */
+void grpc_subchannel_index_ref(void);
+
+/** Decrement the refcount of subchannel index (global). If the refcount drops
+    to zero, unref the subchannel index and destroy its mutex. */
+void grpc_subchannel_index_unref(void);
+
 /** \em TEST ONLY.
  * If \a force_creation is true, all key comparisons will be false, resulting in
  * new subchannels always being created. Otherwise, the keys will be compared as
diff --git a/src/core/ext/filters/http/server/http_server_filter.c b/src/core/ext/filters/http/server/http_server_filter.c
index 554a7f530d..03958136b4 100644
--- a/src/core/ext/filters/http/server/http_server_filter.c
+++ b/src/core/ext/filters/http/server/http_server_filter.c
@@ -83,12 +83,12 @@ static grpc_error *server_filter_outgoing_metadata(grpc_exec_ctx *exec_ctx,
 }
 
 static void add_error(const char *error_name, grpc_error **cumulative,
-                      grpc_error *new) {
-  if (new == GRPC_ERROR_NONE) return;
+                      grpc_error *new_err) {
+  if (new_err == GRPC_ERROR_NONE) return;
   if (*cumulative == GRPC_ERROR_NONE) {
     *cumulative = GRPC_ERROR_CREATE_FROM_COPIED_STRING(error_name);
   }
-  *cumulative = grpc_error_add_child(*cumulative, new);
+  *cumulative = grpc_error_add_child(*cumulative, new_err);
 }
 
 static grpc_error *server_filter_incoming_metadata(grpc_exec_ctx *exec_ctx,
diff --git a/src/core/ext/filters/max_age/max_age_filter.c b/src/core/ext/filters/max_age/max_age_filter.c
index 450f67746f..0ac803ed41 100644
--- a/src/core/ext/filters/max_age/max_age_filter.c
+++ b/src/core/ext/filters/max_age/max_age_filter.c
@@ -402,7 +402,7 @@ static bool maybe_add_max_age_filter(grpc_exec_ctx* exec_ctx,
   bool enable =
       grpc_channel_arg_get_integer(
           grpc_channel_args_find(channel_args, GRPC_ARG_MAX_CONNECTION_AGE_MS),
-          MAX_CONNECTION_AGE_INTEGER_OPTIONS) != INT_MAX &&
+          MAX_CONNECTION_AGE_INTEGER_OPTIONS) != INT_MAX ||
       grpc_channel_arg_get_integer(
           grpc_channel_args_find(channel_args, GRPC_ARG_MAX_CONNECTION_IDLE_MS),
           MAX_CONNECTION_IDLE_INTEGER_OPTIONS) != INT_MAX;
diff --git a/src/core/ext/transport/chttp2/client/chttp2_connector.c b/src/core/ext/transport/chttp2/client/chttp2_connector.c
index 0ec9353c04..202bcd47f5 100644
--- a/src/core/ext/transport/chttp2/client/chttp2_connector.c
+++ b/src/core/ext/transport/chttp2/client/chttp2_connector.c
@@ -161,7 +161,7 @@ static void connected(grpc_exec_ctx *exec_ctx, void *arg, grpc_error *error) {
       grpc_endpoint_shutdown(exec_ctx, c->endpoint, GRPC_ERROR_REF(error));
     }
     gpr_mu_unlock(&c->mu);
-    chttp2_connector_unref(exec_ctx, arg);
+    chttp2_connector_unref(exec_ctx, (grpc_connector *)arg);
   } else {
     GPR_ASSERT(c->endpoint != NULL);
     start_handshake_locked(exec_ctx, c);
diff --git a/src/core/ext/transport/chttp2/server/chttp2_server.c b/src/core/ext/transport/chttp2/server/chttp2_server.c
index d7add0538b..f5a409a403 100644
--- a/src/core/ext/transport/chttp2/server/chttp2_server.c
+++ b/src/core/ext/transport/chttp2/server/chttp2_server.c
@@ -52,7 +52,7 @@ typedef struct {
 } server_state;
 
 typedef struct {
-  server_state *server_state;
+  server_state *svr_state;
   grpc_pollset *accepting_pollset;
   grpc_tcp_server_acceptor *acceptor;
   grpc_handshake_manager *handshake_mgr;
@@ -63,8 +63,8 @@ static void on_handshake_done(grpc_exec_ctx *exec_ctx, void *arg,
   grpc_handshaker_args *args = (grpc_handshaker_args *)arg;
   server_connection_state *connection_state =
       (server_connection_state *)args->user_data;
-  gpr_mu_lock(&connection_state->server_state->mu);
-  if (error != GRPC_ERROR_NONE || connection_state->server_state->shutdown) {
+  gpr_mu_lock(&connection_state->svr_state->mu);
+  if (error != GRPC_ERROR_NONE || connection_state->svr_state->shutdown) {
     const char *error_str = grpc_error_string(error);
     gpr_log(GPR_DEBUG, "Handshaking failed: %s", error_str);
 
@@ -89,7 +89,7 @@ static void on_handshake_done(grpc_exec_ctx *exec_ctx, void *arg,
       grpc_transport *transport =
           grpc_create_chttp2_transport(exec_ctx, args->args, args->endpoint, 0);
       grpc_server_setup_transport(
-          exec_ctx, connection_state->server_state->server, transport,
+          exec_ctx, connection_state->svr_state->server, transport,
           connection_state->accepting_pollset, args->args);
       grpc_chttp2_transport_start_reading(exec_ctx, transport,
                                           args->read_buffer);
@@ -97,11 +97,11 @@ static void on_handshake_done(grpc_exec_ctx *exec_ctx, void *arg,
     }
   }
   grpc_handshake_manager_pending_list_remove(
-      &connection_state->server_state->pending_handshake_mgrs,
+      &connection_state->svr_state->pending_handshake_mgrs,
       connection_state->handshake_mgr);
-  gpr_mu_unlock(&connection_state->server_state->mu);
+  gpr_mu_unlock(&connection_state->svr_state->mu);
   grpc_handshake_manager_destroy(exec_ctx, connection_state->handshake_mgr);
-  grpc_tcp_server_unref(exec_ctx, connection_state->server_state->tcp_server);
+  grpc_tcp_server_unref(exec_ctx, connection_state->svr_state->tcp_server);
   gpr_free(connection_state->acceptor);
   gpr_free(connection_state);
 }
@@ -124,8 +124,8 @@ static void on_accept(grpc_exec_ctx *exec_ctx, void *arg, grpc_endpoint *tcp,
   gpr_mu_unlock(&state->mu);
   grpc_tcp_server_ref(state->tcp_server);
   server_connection_state *connection_state =
-      gpr_malloc(sizeof(*connection_state));
-  connection_state->server_state = state;
+      (server_connection_state *)gpr_malloc(sizeof(*connection_state));
+  connection_state->svr_state = state;
   connection_state->accepting_pollset = accepting_pollset;
   connection_state->acceptor = acceptor;
   connection_state->handshake_mgr = handshake_mgr;
diff --git a/src/core/ext/transport/chttp2/transport/chttp2_transport.c b/src/core/ext/transport/chttp2/transport/chttp2_transport.c
index 3fd701fe2f..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(
@@ -2912,7 +3006,8 @@ grpc_chttp2_incoming_byte_stream *grpc_chttp2_incoming_byte_stream_create(
     grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t, grpc_chttp2_stream *s,
     uint32_t frame_size, uint32_t flags) {
   grpc_chttp2_incoming_byte_stream *incoming_byte_stream =
-      gpr_malloc(sizeof(*incoming_byte_stream));
+      (grpc_chttp2_incoming_byte_stream *)gpr_malloc(
+          sizeof(*incoming_byte_stream));
   incoming_byte_stream->base.length = frame_size;
   incoming_byte_stream->remaining_bytes = frame_size;
   incoming_byte_stream->base.flags = flags;
@@ -3016,6 +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/flow_control.c b/src/core/ext/transport/chttp2/transport/flow_control.c
index 0f078e79e9..569a6349d3 100644
--- a/src/core/ext/transport/chttp2/transport/flow_control.c
+++ b/src/core/ext/transport/chttp2/transport/flow_control.c
@@ -60,24 +60,24 @@ static void pretrace(shadow_flow_control* shadow_fc,
 
 #define TRACE_PADDING 30
 
-static char* fmt_int64_diff_str(int64_t old, int64_t new) {
+static char* fmt_int64_diff_str(int64_t old_val, int64_t new_val) {
   char* str;
-  if (old != new) {
-    gpr_asprintf(&str, "%" PRId64 " -> %" PRId64 "", old, new);
+  if (old_val != new_val) {
+    gpr_asprintf(&str, "%" PRId64 " -> %" PRId64 "", old_val, new_val);
   } else {
-    gpr_asprintf(&str, "%" PRId64 "", old);
+    gpr_asprintf(&str, "%" PRId64 "", old_val);
   }
   char* str_lp = gpr_leftpad(str, ' ', TRACE_PADDING);
   gpr_free(str);
   return str_lp;
 }
 
-static char* fmt_uint32_diff_str(uint32_t old, uint32_t new) {
+static char* fmt_uint32_diff_str(uint32_t old_val, uint32_t new_val) {
   char* str;
-  if (new > 0 && old != new) {
-    gpr_asprintf(&str, "%" PRIu32 " -> %" PRIu32 "", old, new);
+  if (new_val > 0 && old_val != new_val) {
+    gpr_asprintf(&str, "%" PRIu32 " -> %" PRIu32 "", old_val, new_val);
   } else {
-    gpr_asprintf(&str, "%" PRIu32 "", old);
+    gpr_asprintf(&str, "%" PRIu32 "", old_val);
   }
   char* str_lp = gpr_leftpad(str, ' ', TRACE_PADDING);
   gpr_free(str);
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_settings.c b/src/core/ext/transport/chttp2/transport/frame_settings.c
index 806100adaa..2995bf7310 100644
--- a/src/core/ext/transport/chttp2/transport/frame_settings.c
+++ b/src/core/ext/transport/chttp2/transport/frame_settings.c
@@ -44,7 +44,8 @@ static uint8_t *fill_header(uint8_t *out, uint32_t length, uint8_t flags) {
   return out;
 }
 
-grpc_slice grpc_chttp2_settings_create(uint32_t *old, const uint32_t *new,
+grpc_slice grpc_chttp2_settings_create(uint32_t *old_settings,
+                                       const uint32_t *new_settings,
                                        uint32_t force_mask, size_t count) {
   size_t i;
   uint32_t n = 0;
@@ -52,21 +53,21 @@ grpc_slice grpc_chttp2_settings_create(uint32_t *old, const uint32_t *new,
   uint8_t *p;
 
   for (i = 0; i < count; i++) {
-    n += (new[i] != old[i] || (force_mask & (1u << i)) != 0);
+    n += (new_settings[i] != old_settings[i] || (force_mask & (1u << i)) != 0);
   }
 
   output = GRPC_SLICE_MALLOC(9 + 6 * n);
   p = fill_header(GRPC_SLICE_START_PTR(output), 6 * n, 0);
 
   for (i = 0; i < count; i++) {
-    if (new[i] != old[i] || (force_mask & (1u << i)) != 0) {
+    if (new_settings[i] != old_settings[i] || (force_mask & (1u << i)) != 0) {
       *p++ = (uint8_t)(grpc_setting_id_to_wire_id[i] >> 8);
       *p++ = (uint8_t)(grpc_setting_id_to_wire_id[i]);
-      *p++ = (uint8_t)(new[i] >> 24);
-      *p++ = (uint8_t)(new[i] >> 16);
-      *p++ = (uint8_t)(new[i] >> 8);
-      *p++ = (uint8_t)(new[i]);
-      old[i] = new[i];
+      *p++ = (uint8_t)(new_settings[i] >> 24);
+      *p++ = (uint8_t)(new_settings[i] >> 16);
+      *p++ = (uint8_t)(new_settings[i] >> 8);
+      *p++ = (uint8_t)(new_settings[i]);
+      old_settings[i] = new_settings[i];
     }
   }
 
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/incoming_metadata.c b/src/core/ext/transport/chttp2/transport/incoming_metadata.c
index cf0a9ca920..ba680a89db 100644
--- a/src/core/ext/transport/chttp2/transport/incoming_metadata.c
+++ b/src/core/ext/transport/chttp2/transport/incoming_metadata.c
@@ -42,8 +42,9 @@ grpc_error *grpc_chttp2_incoming_metadata_buffer_add(
     grpc_mdelem elem) {
   buffer->size += GRPC_MDELEM_LENGTH(elem);
   return grpc_metadata_batch_add_tail(
-      exec_ctx, &buffer->batch,
-      gpr_arena_alloc(buffer->arena, sizeof(grpc_linked_mdelem)), elem);
+      exec_ctx, &buffer->batch, (grpc_linked_mdelem *)gpr_arena_alloc(
+                                    buffer->arena, sizeof(grpc_linked_mdelem)),
+      elem);
 }
 
 grpc_error *grpc_chttp2_incoming_metadata_buffer_replace_or_add(
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/stream_map.c b/src/core/ext/transport/chttp2/transport/stream_map.c
index 650090d8f0..d6079a9a33 100644
--- a/src/core/ext/transport/chttp2/transport/stream_map.c
+++ b/src/core/ext/transport/chttp2/transport/stream_map.c
@@ -72,8 +72,10 @@ void grpc_chttp2_stream_map_add(grpc_chttp2_stream_map *map, uint32_t key,
       /* resize when less than 25% of the table is free, because compaction
          won't help much */
       map->capacity = capacity = 3 * capacity / 2;
-      map->keys = keys = gpr_realloc(keys, capacity * sizeof(uint32_t));
-      map->values = values = gpr_realloc(values, capacity * sizeof(void *));
+      map->keys = keys =
+          (uint32_t *)gpr_realloc(keys, capacity * sizeof(uint32_t));
+      map->values = values =
+          (void **)gpr_realloc(values, capacity * sizeof(void *));
     }
   }
 
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/ext/transport/inproc/inproc_transport.c b/src/core/ext/transport/inproc/inproc_transport.c
index 036853a53b..cd3e76a0b5 100644
--- a/src/core/ext/transport/inproc/inproc_transport.c
+++ b/src/core/ext/transport/inproc/inproc_transport.c
@@ -37,7 +37,6 @@
     if (GRPC_TRACER_ON(grpc_inproc_trace)) gpr_log(__VA_ARGS__); \
   } while (0)
 
-static const grpc_transport_vtable inproc_vtable;
 static grpc_slice g_empty_slice;
 static grpc_slice g_fake_path_key;
 static grpc_slice g_fake_path_value;
@@ -1167,6 +1166,55 @@ static void destroy_transport(grpc_exec_ctx *exec_ctx, grpc_transport *gt) {
 }
 
 /*******************************************************************************
+ * INTEGRATION GLUE
+ */
+
+static void set_pollset(grpc_exec_ctx *exec_ctx, grpc_transport *gt,
+                        grpc_stream *gs, grpc_pollset *pollset) {
+  // Nothing to do here
+}
+
+static void set_pollset_set(grpc_exec_ctx *exec_ctx, grpc_transport *gt,
+                            grpc_stream *gs, grpc_pollset_set *pollset_set) {
+  // Nothing to do here
+}
+
+static grpc_endpoint *get_endpoint(grpc_exec_ctx *exec_ctx, grpc_transport *t) {
+  return NULL;
+}
+
+/*******************************************************************************
+ * GLOBAL INIT AND DESTROY
+ */
+static void do_nothing(grpc_exec_ctx *exec_ctx, void *arg, grpc_error *error) {}
+
+void grpc_inproc_transport_init(void) {
+  grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
+  GRPC_CLOSURE_INIT(&do_nothing_closure, do_nothing, NULL,
+                    grpc_schedule_on_exec_ctx);
+  g_empty_slice = grpc_slice_from_static_buffer(NULL, 0);
+
+  grpc_slice key_tmp = grpc_slice_from_static_string(":path");
+  g_fake_path_key = grpc_slice_intern(key_tmp);
+  grpc_slice_unref_internal(&exec_ctx, key_tmp);
+
+  g_fake_path_value = grpc_slice_from_static_string("/");
+
+  grpc_slice auth_tmp = grpc_slice_from_static_string(":authority");
+  g_fake_auth_key = grpc_slice_intern(auth_tmp);
+  grpc_slice_unref_internal(&exec_ctx, auth_tmp);
+
+  g_fake_auth_value = grpc_slice_from_static_string("inproc-fail");
+  grpc_exec_ctx_finish(&exec_ctx);
+}
+
+static const grpc_transport_vtable inproc_vtable = {
+    sizeof(inproc_stream), "inproc",        init_stream,
+    set_pollset,           set_pollset_set, perform_stream_op,
+    perform_transport_op,  destroy_stream,  destroy_transport,
+    get_endpoint};
+
+/*******************************************************************************
  * Main inproc transport functions
  */
 static void inproc_transports_create(grpc_exec_ctx *exec_ctx,
@@ -1178,7 +1226,7 @@ static void inproc_transports_create(grpc_exec_ctx *exec_ctx,
   inproc_transport *st = (inproc_transport *)gpr_zalloc(sizeof(*st));
   inproc_transport *ct = (inproc_transport *)gpr_zalloc(sizeof(*ct));
   // Share one lock between both sides since both sides get affected
-  st->mu = ct->mu = gpr_malloc(sizeof(*st->mu));
+  st->mu = ct->mu = (shared_mu *)gpr_malloc(sizeof(*st->mu));
   gpr_mu_init(&st->mu->mu);
   gpr_ref_init(&st->mu->refs, 2);
   st->base.vtable = &inproc_vtable;
@@ -1240,55 +1288,6 @@ grpc_channel *grpc_inproc_channel_create(grpc_server *server,
   return channel;
 }
 
-/*******************************************************************************
- * INTEGRATION GLUE
- */
-
-static void set_pollset(grpc_exec_ctx *exec_ctx, grpc_transport *gt,
-                        grpc_stream *gs, grpc_pollset *pollset) {
-  // Nothing to do here
-}
-
-static void set_pollset_set(grpc_exec_ctx *exec_ctx, grpc_transport *gt,
-                            grpc_stream *gs, grpc_pollset_set *pollset_set) {
-  // Nothing to do here
-}
-
-static grpc_endpoint *get_endpoint(grpc_exec_ctx *exec_ctx, grpc_transport *t) {
-  return NULL;
-}
-
-static const grpc_transport_vtable inproc_vtable = {
-    sizeof(inproc_stream), "inproc",        init_stream,
-    set_pollset,           set_pollset_set, perform_stream_op,
-    perform_transport_op,  destroy_stream,  destroy_transport,
-    get_endpoint};
-
-/*******************************************************************************
- * GLOBAL INIT AND DESTROY
- */
-static void do_nothing(grpc_exec_ctx *exec_ctx, void *arg, grpc_error *error) {}
-
-void grpc_inproc_transport_init(void) {
-  grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
-  GRPC_CLOSURE_INIT(&do_nothing_closure, do_nothing, NULL,
-                    grpc_schedule_on_exec_ctx);
-  g_empty_slice = grpc_slice_from_static_buffer(NULL, 0);
-
-  grpc_slice key_tmp = grpc_slice_from_static_string(":path");
-  g_fake_path_key = grpc_slice_intern(key_tmp);
-  grpc_slice_unref_internal(&exec_ctx, key_tmp);
-
-  g_fake_path_value = grpc_slice_from_static_string("/");
-
-  grpc_slice auth_tmp = grpc_slice_from_static_string(":authority");
-  g_fake_auth_key = grpc_slice_intern(auth_tmp);
-  grpc_slice_unref_internal(&exec_ctx, auth_tmp);
-
-  g_fake_auth_value = grpc_slice_from_static_string("inproc-fail");
-  grpc_exec_ctx_finish(&exec_ctx);
-}
-
 void grpc_inproc_transport_shutdown(void) {
   grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
   grpc_slice_unref_internal(&exec_ctx, g_empty_slice);
diff --git a/src/core/lib/debug/stats_data.c b/src/core/lib/debug/stats_data.c
index 1a020a15c3..0f3e49522f 100644
--- a/src/core/lib/debug/stats_data.c
+++ b/src/core/lib/debug/stats_data.c
@@ -25,6 +25,10 @@
 const char *grpc_stats_counter_name[GRPC_STATS_COUNTER_COUNT] = {
     "client_calls_created",
     "server_calls_created",
+    "cqs_created",
+    "client_channels_created",
+    "client_subchannels_created",
+    "server_channels_created",
     "syscall_poll",
     "syscall_wait",
     "pollset_kick",
@@ -52,6 +56,27 @@ 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",
@@ -68,6 +93,8 @@ const char *grpc_stats_counter_name[GRPC_STATS_COUNTER_COUNT] = {
 const char *grpc_stats_counter_doc[GRPC_STATS_COUNTER_COUNT] = {
     "Number of client side calls created by this process",
     "Number of server side calls created by this process",
+    "Number of completion queues created", "Number of client channels created",
+    "Number of client subchannels created", "Number of server channels created",
     "Number of polling syscalls (epoll_wait, poll, etc) made by this process",
     "Number of sleeping syscalls made by this process",
     "How many polling wakeups were performed by the process (only valid for "
@@ -104,6 +131,30 @@ 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 48f60fc8c9..e7cb903053 100644
--- a/src/core/lib/debug/stats_data.h
+++ b/src/core/lib/debug/stats_data.h
@@ -27,6 +27,10 @@
 typedef enum {
   GRPC_STATS_COUNTER_CLIENT_CALLS_CREATED,
   GRPC_STATS_COUNTER_SERVER_CALLS_CREATED,
+  GRPC_STATS_COUNTER_CQS_CREATED,
+  GRPC_STATS_COUNTER_CLIENT_CHANNELS_CREATED,
+  GRPC_STATS_COUNTER_CLIENT_SUBCHANNELS_CREATED,
+  GRPC_STATS_COUNTER_SERVER_CHANNELS_CREATED,
   GRPC_STATS_COUNTER_SYSCALL_POLL,
   GRPC_STATS_COUNTER_SYSCALL_WAIT,
   GRPC_STATS_COUNTER_POLLSET_KICK,
@@ -54,6 +58,27 @@ 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,
@@ -121,6 +146,15 @@ typedef enum {
   GRPC_STATS_INC_COUNTER((exec_ctx), GRPC_STATS_COUNTER_CLIENT_CALLS_CREATED)
 #define GRPC_STATS_INC_SERVER_CALLS_CREATED(exec_ctx) \
   GRPC_STATS_INC_COUNTER((exec_ctx), GRPC_STATS_COUNTER_SERVER_CALLS_CREATED)
+#define GRPC_STATS_INC_CQS_CREATED(exec_ctx) \
+  GRPC_STATS_INC_COUNTER((exec_ctx), GRPC_STATS_COUNTER_CQS_CREATED)
+#define GRPC_STATS_INC_CLIENT_CHANNELS_CREATED(exec_ctx) \
+  GRPC_STATS_INC_COUNTER((exec_ctx), GRPC_STATS_COUNTER_CLIENT_CHANNELS_CREATED)
+#define GRPC_STATS_INC_CLIENT_SUBCHANNELS_CREATED(exec_ctx) \
+  GRPC_STATS_INC_COUNTER((exec_ctx),                        \
+                         GRPC_STATS_COUNTER_CLIENT_SUBCHANNELS_CREATED)
+#define GRPC_STATS_INC_SERVER_CHANNELS_CREATED(exec_ctx) \
+  GRPC_STATS_INC_COUNTER((exec_ctx), GRPC_STATS_COUNTER_SERVER_CHANNELS_CREATED)
 #define GRPC_STATS_INC_SYSCALL_POLL(exec_ctx) \
   GRPC_STATS_INC_COUNTER((exec_ctx), GRPC_STATS_COUNTER_SYSCALL_POLL)
 #define GRPC_STATS_INC_SYSCALL_WAIT(exec_ctx) \
@@ -181,6 +215,95 @@ 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 b43c466d4f..8ba07a4817 100644
--- a/src/core/lib/debug/stats_data.yaml
+++ b/src/core/lib/debug/stats_data.yaml
@@ -24,6 +24,14 @@
   max: 262144
   buckets: 64
   doc: Initial size of the grpc_call arena created at call start
+- counter: cqs_created
+  doc: Number of completion queues created
+- counter: client_channels_created
+  doc: Number of client channels created
+- counter: client_subchannels_created
+  doc: Number of client subchannels created
+- counter: server_channels_created
+  doc: Number of server channels created
 # polling
 - counter: syscall_poll
   doc: Number of polling syscalls (epoll_wait, poll, etc) made by this process
@@ -139,6 +147,48 @@
 - 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 4cf53f3f79..01c25cce9f 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,
 pollset_kick_per_iteration:FLOAT,
@@ -27,6 +31,27 @@ 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/ev_epoll1_linux.c b/src/core/lib/iomgr/ev_epoll1_linux.c
index aa861d3cc1..7058acca50 100644
--- a/src/core/lib/iomgr/ev_epoll1_linux.c
+++ b/src/core/lib/iomgr/ev_epoll1_linux.c
@@ -130,9 +130,9 @@ static void fd_global_shutdown(void);
  * Pollset Declarations
  */
 
-typedef enum { UNKICKED, KICKED, DESIGNATED_POLLER } kick_state_t;
+typedef enum { UNKICKED, KICKED, DESIGNATED_POLLER } kick_state;
 
-static const char *kick_state_string(kick_state_t st) {
+static const char *kick_state_string(kick_state st) {
   switch (st) {
     case UNKICKED:
       return "UNKICKED";
@@ -145,7 +145,7 @@ static const char *kick_state_string(kick_state_t st) {
 }
 
 struct grpc_pollset_worker {
-  kick_state_t kick_state;
+  kick_state state;
   int kick_state_mutator;  // which line of code last changed kick state
   bool initialized_cv;
   grpc_pollset_worker *next;
@@ -154,9 +154,9 @@ struct grpc_pollset_worker {
   grpc_closure_list schedule_on_end_work;
 };
 
-#define SET_KICK_STATE(worker, state)        \
+#define SET_KICK_STATE(worker, kick_state)   \
   do {                                       \
-    (worker)->kick_state = (state);          \
+    (worker)->state = (kick_state);          \
     (worker)->kick_state_mutator = __LINE__; \
   } while (false)
 
@@ -510,7 +510,7 @@ static grpc_error *pollset_kick_all(grpc_exec_ctx *exec_ctx,
     grpc_pollset_worker *worker = pollset->root_worker;
     do {
       GRPC_STATS_INC_POLLSET_KICK(exec_ctx);
-      switch (worker->kick_state) {
+      switch (worker->state) {
         case KICKED:
           GRPC_STATS_INC_POLLSET_KICKED_AGAIN(exec_ctx);
           break;
@@ -695,7 +695,7 @@ static bool begin_worker(grpc_pollset *pollset, grpc_pollset_worker *worker,
     gpr_mu_lock(&pollset->mu);
     if (GRPC_TRACER_ON(grpc_polling_trace)) {
       gpr_log(GPR_ERROR, "PS:%p BEGIN_REORG:%p kick_state=%s is_reassigning=%d",
-              pollset, worker, kick_state_string(worker->kick_state),
+              pollset, worker, kick_state_string(worker->state),
               is_reassigning);
     }
     if (pollset->seen_inactive) {
@@ -715,12 +715,12 @@ static bool begin_worker(grpc_pollset *pollset, grpc_pollset_worker *worker,
          at this point is if it were "kicked specifically". Since the worker has
          not added itself to the pollset yet (by calling worker_insert()), it is
          not visible in the "kick any" path yet */
-      if (worker->kick_state == UNKICKED) {
+      if (worker->state == UNKICKED) {
         pollset->seen_inactive = false;
         if (neighborhood->active_root == NULL) {
           neighborhood->active_root = pollset->next = pollset->prev = pollset;
           /* Make this the designated poller if there isn't one already */
-          if (worker->kick_state == UNKICKED &&
+          if (worker->state == UNKICKED &&
               gpr_atm_no_barrier_cas(&g_active_poller, 0, (gpr_atm)worker)) {
             SET_KICK_STATE(worker, DESIGNATED_POLLER);
           }
@@ -740,19 +740,19 @@ static bool begin_worker(grpc_pollset *pollset, grpc_pollset_worker *worker,
 
   worker_insert(pollset, worker);
   pollset->begin_refs--;
-  if (worker->kick_state == UNKICKED && !pollset->kicked_without_poller) {
+  if (worker->state == UNKICKED && !pollset->kicked_without_poller) {
     GPR_ASSERT(gpr_atm_no_barrier_load(&g_active_poller) != (gpr_atm)worker);
     worker->initialized_cv = true;
     gpr_cv_init(&worker->cv);
-    while (worker->kick_state == UNKICKED && !pollset->shutting_down) {
+    while (worker->state == UNKICKED && !pollset->shutting_down) {
       if (GRPC_TRACER_ON(grpc_polling_trace)) {
         gpr_log(GPR_ERROR, "PS:%p BEGIN_WAIT:%p kick_state=%s shutdown=%d",
-                pollset, worker, kick_state_string(worker->kick_state),
+                pollset, worker, kick_state_string(worker->state),
                 pollset->shutting_down);
       }
 
       if (gpr_cv_wait(&worker->cv, &pollset->mu, deadline) &&
-          worker->kick_state == UNKICKED) {
+          worker->state == UNKICKED) {
         /* If gpr_cv_wait returns true (i.e a timeout), pretend that the worker
            received a kick */
         SET_KICK_STATE(worker, KICKED);
@@ -765,7 +765,7 @@ static bool begin_worker(grpc_pollset *pollset, grpc_pollset_worker *worker,
     gpr_log(GPR_ERROR,
             "PS:%p BEGIN_DONE:%p kick_state=%s shutdown=%d "
             "kicked_without_poller: %d",
-            pollset, worker, kick_state_string(worker->kick_state),
+            pollset, worker, kick_state_string(worker->state),
             pollset->shutting_down, pollset->kicked_without_poller);
   }
 
@@ -785,7 +785,7 @@ static bool begin_worker(grpc_pollset *pollset, grpc_pollset_worker *worker,
   }
 
   GPR_TIMER_END("begin_worker", 0);
-  return worker->kick_state == DESIGNATED_POLLER && !pollset->shutting_down;
+  return worker->state == DESIGNATED_POLLER && !pollset->shutting_down;
 }
 
 static bool check_neighborhood_for_available_poller(
@@ -802,7 +802,7 @@ static bool check_neighborhood_for_available_poller(
     grpc_pollset_worker *inspect_worker = inspect->root_worker;
     if (inspect_worker != NULL) {
       do {
-        switch (inspect_worker->kick_state) {
+        switch (inspect_worker->state) {
           case UNKICKED:
             if (gpr_atm_no_barrier_cas(&g_active_poller, 0,
                                        (gpr_atm)inspect_worker)) {
@@ -866,7 +866,7 @@ static void end_worker(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset,
   grpc_closure_list_move(&worker->schedule_on_end_work,
                          &exec_ctx->closure_list);
   if (gpr_atm_no_barrier_load(&g_active_poller) == (gpr_atm)worker) {
-    if (worker->next != worker && worker->next->kick_state == UNKICKED) {
+    if (worker->next != worker && worker->next->state == UNKICKED) {
       if (GRPC_TRACER_ON(grpc_polling_trace)) {
         gpr_log(GPR_DEBUG, " .. choose next poller to be peer %p", worker);
       }
@@ -1005,14 +1005,14 @@ static grpc_error *pollset_kick(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset,
     gpr_strvec_add(&log, tmp);
     if (pollset->root_worker != NULL) {
       gpr_asprintf(&tmp, " {kick_state=%s next=%p {kick_state=%s}}",
-                   kick_state_string(pollset->root_worker->kick_state),
+                   kick_state_string(pollset->root_worker->state),
                    pollset->root_worker->next,
-                   kick_state_string(pollset->root_worker->next->kick_state));
+                   kick_state_string(pollset->root_worker->next->state));
       gpr_strvec_add(&log, tmp);
     }
     if (specific_worker != NULL) {
       gpr_asprintf(&tmp, " worker_kick_state=%s",
-                   kick_state_string(specific_worker->kick_state));
+                   kick_state_string(specific_worker->state));
       gpr_strvec_add(&log, tmp);
     }
     tmp = gpr_strvec_flatten(&log, NULL);
@@ -1033,14 +1033,14 @@ static grpc_error *pollset_kick(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset,
         goto done;
       }
       grpc_pollset_worker *next_worker = root_worker->next;
-      if (root_worker->kick_state == KICKED) {
+      if (root_worker->state == KICKED) {
         GRPC_STATS_INC_POLLSET_KICKED_AGAIN(exec_ctx);
         if (GRPC_TRACER_ON(grpc_polling_trace)) {
           gpr_log(GPR_ERROR, " .. already kicked %p", root_worker);
         }
         SET_KICK_STATE(root_worker, KICKED);
         goto done;
-      } else if (next_worker->kick_state == KICKED) {
+      } else if (next_worker->state == KICKED) {
         GRPC_STATS_INC_POLLSET_KICKED_AGAIN(exec_ctx);
         if (GRPC_TRACER_ON(grpc_polling_trace)) {
           gpr_log(GPR_ERROR, " .. already kicked %p", next_worker);
@@ -1059,7 +1059,7 @@ static grpc_error *pollset_kick(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset,
         SET_KICK_STATE(root_worker, KICKED);
         ret_err = grpc_wakeup_fd_wakeup(&global_wakeup_fd);
         goto done;
-      } else if (next_worker->kick_state == UNKICKED) {
+      } else if (next_worker->state == UNKICKED) {
         GRPC_STATS_INC_POLLSET_KICK_WAKEUP_CV(exec_ctx);
         if (GRPC_TRACER_ON(grpc_polling_trace)) {
           gpr_log(GPR_ERROR, " .. kicked %p", next_worker);
@@ -1068,8 +1068,8 @@ static grpc_error *pollset_kick(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset,
         SET_KICK_STATE(next_worker, KICKED);
         gpr_cv_signal(&next_worker->cv);
         goto done;
-      } else if (next_worker->kick_state == DESIGNATED_POLLER) {
-        if (root_worker->kick_state != DESIGNATED_POLLER) {
+      } else if (next_worker->state == DESIGNATED_POLLER) {
+        if (root_worker->state != DESIGNATED_POLLER) {
           if (GRPC_TRACER_ON(grpc_polling_trace)) {
             gpr_log(
                 GPR_ERROR,
@@ -1094,7 +1094,7 @@ static grpc_error *pollset_kick(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset,
         }
       } else {
         GRPC_STATS_INC_POLLSET_KICKED_AGAIN(exec_ctx);
-        GPR_ASSERT(next_worker->kick_state == KICKED);
+        GPR_ASSERT(next_worker->state == KICKED);
         SET_KICK_STATE(next_worker, KICKED);
         goto done;
       }
@@ -1109,7 +1109,7 @@ static grpc_error *pollset_kick(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset,
     GPR_UNREACHABLE_CODE(goto done);
   }
 
-  if (specific_worker->kick_state == KICKED) {
+  if (specific_worker->state == KICKED) {
     if (GRPC_TRACER_ON(grpc_polling_trace)) {
       gpr_log(GPR_ERROR, " .. specific worker already kicked");
     }
diff --git a/src/core/lib/iomgr/ev_epollex_linux.c b/src/core/lib/iomgr/ev_epollex_linux.c
index 4e5bed5016..2a276ca360 100644
--- a/src/core/lib/iomgr/ev_epollex_linux.c
+++ b/src/core/lib/iomgr/ev_epollex_linux.c
@@ -97,12 +97,12 @@ static void pg_join(grpc_exec_ctx *exec_ctx, polling_group *pg,
  * pollable Declarations
  */
 
-typedef struct pollable_t {
+typedef struct pollable {
   polling_obj po;
   int epfd;
   grpc_wakeup_fd wakeup;
   grpc_pollset_worker *root_worker;
-} pollable_t;
+} pollable;
 
 static const char *polling_obj_type_string(polling_obj_type t) {
   switch (t) {
@@ -122,7 +122,7 @@ static const char *polling_obj_type_string(polling_obj_type t) {
   return "<invalid>";
 }
 
-static char *pollable_desc(pollable_t *p) {
+static char *pollable_desc(pollable *p) {
   char *out;
   gpr_asprintf(&out, "type=%s group=%p epfd=%d wakeup=%d",
                polling_obj_type_string(p->po.type), p->po.group, p->epfd,
@@ -130,19 +130,19 @@ static char *pollable_desc(pollable_t *p) {
   return out;
 }
 
-static pollable_t g_empty_pollable;
+static pollable g_empty_pollable;
 
-static void pollable_init(pollable_t *p, polling_obj_type type);
-static void pollable_destroy(pollable_t *p);
+static void pollable_init(pollable *p, polling_obj_type type);
+static void pollable_destroy(pollable *p);
 /* ensure that p->epfd, p->wakeup are initialized; p->po.mu must be held */
-static grpc_error *pollable_materialize(pollable_t *p);
+static grpc_error *pollable_materialize(pollable *p);
 
 /*******************************************************************************
  * Fd Declarations
  */
 
 struct grpc_fd {
-  pollable_t pollable;
+  pollable pollable_obj;
   int fd;
   /* refst format:
        bit 0    : 1=Active / 0=Orphaned
@@ -193,15 +193,15 @@ struct grpc_pollset_worker {
   pollset_worker_link links[POLLSET_WORKER_LINK_COUNT];
   gpr_cv cv;
   grpc_pollset *pollset;
-  pollable_t *pollable;
+  pollable *pollable_obj;
 };
 
 #define MAX_EPOLL_EVENTS 100
 #define MAX_EPOLL_EVENTS_HANDLED_EACH_POLL_CALL 5
 
 struct grpc_pollset {
-  pollable_t pollable;
-  pollable_t *current_pollable;
+  pollable pollable_obj;
+  pollable *current_pollable_obj;
   int kick_alls_pending;
   bool kicked_without_poller;
   grpc_closure *shutdown_closure;
@@ -282,7 +282,7 @@ static void fd_destroy(grpc_exec_ctx *exec_ctx, void *arg, grpc_error *error) {
   grpc_fd *fd = (grpc_fd *)arg;
   /* Add the fd to the freelist */
   grpc_iomgr_unregister_object(&fd->iomgr_object);
-  pollable_destroy(&fd->pollable);
+  pollable_destroy(&fd->pollable_obj);
   gpr_mu_destroy(&fd->orphaned_mu);
   gpr_mu_lock(&fd_freelist_mu);
   fd->freelist_next = fd_freelist;
@@ -343,7 +343,7 @@ static grpc_fd *fd_create(int fd, const char *name) {
     new_fd = (grpc_fd *)gpr_malloc(sizeof(grpc_fd));
   }
 
-  pollable_init(&new_fd->pollable, PO_FD);
+  pollable_init(&new_fd->pollable_obj, PO_FD);
 
   gpr_atm_rel_store(&new_fd->refst, (gpr_atm)1);
   new_fd->fd = fd;
@@ -385,7 +385,7 @@ static void fd_orphan(grpc_exec_ctx *exec_ctx, grpc_fd *fd,
   bool is_fd_closed = already_closed;
   grpc_error *error = GRPC_ERROR_NONE;
 
-  gpr_mu_lock(&fd->pollable.po.mu);
+  gpr_mu_lock(&fd->pollable_obj.po.mu);
   gpr_mu_lock(&fd->orphaned_mu);
   fd->on_done_closure = on_done;
 
@@ -411,7 +411,7 @@ static void fd_orphan(grpc_exec_ctx *exec_ctx, grpc_fd *fd,
   GRPC_CLOSURE_SCHED(exec_ctx, fd->on_done_closure, GRPC_ERROR_REF(error));
 
   gpr_mu_unlock(&fd->orphaned_mu);
-  gpr_mu_unlock(&fd->pollable.po.mu);
+  gpr_mu_unlock(&fd->pollable_obj.po.mu);
   UNREF_BY(exec_ctx, fd, 2, reason); /* Drop the reference */
   GRPC_LOG_IF_ERROR("fd_orphan", GRPC_ERROR_REF(error));
   GRPC_ERROR_UNREF(error);
@@ -451,13 +451,13 @@ static void fd_notify_on_write(grpc_exec_ctx *exec_ctx, grpc_fd *fd,
  * Pollable Definitions
  */
 
-static void pollable_init(pollable_t *p, polling_obj_type type) {
+static void pollable_init(pollable *p, polling_obj_type type) {
   po_init(&p->po, type);
   p->root_worker = NULL;
   p->epfd = -1;
 }
 
-static void pollable_destroy(pollable_t *p) {
+static void pollable_destroy(pollable *p) {
   po_destroy(&p->po);
   if (p->epfd != -1) {
     close(p->epfd);
@@ -466,7 +466,7 @@ static void pollable_destroy(pollable_t *p) {
 }
 
 /* ensure that p->epfd, p->wakeup are initialized; p->po.mu must be held */
-static grpc_error *pollable_materialize(pollable_t *p) {
+static grpc_error *pollable_materialize(pollable *p) {
   if (p->epfd == -1) {
     int new_epfd = epoll_create1(EPOLL_CLOEXEC);
     if (new_epfd < 0) {
@@ -492,7 +492,7 @@ static grpc_error *pollable_materialize(pollable_t *p) {
 }
 
 /* pollable must be materialized */
-static grpc_error *pollable_add_fd(pollable_t *p, grpc_fd *fd) {
+static grpc_error *pollable_add_fd(pollable *p, grpc_fd *fd) {
   grpc_error *error = GRPC_ERROR_NONE;
   static const char *err_desc = "pollable_add_fd";
   const int epfd = p->epfd;
@@ -557,31 +557,34 @@ static void do_kick_all(grpc_exec_ctx *exec_ctx, void *arg,
                         grpc_error *error_unused) {
   grpc_error *error = GRPC_ERROR_NONE;
   grpc_pollset *pollset = (grpc_pollset *)arg;
-  gpr_mu_lock(&pollset->pollable.po.mu);
+  gpr_mu_lock(&pollset->pollable_obj.po.mu);
   if (pollset->root_worker != NULL) {
     grpc_pollset_worker *worker = pollset->root_worker;
     do {
       GRPC_STATS_INC_POLLSET_KICK(exec_ctx);
-      if (worker->pollable != &pollset->pollable) {
-        gpr_mu_lock(&worker->pollable->po.mu);
+      if (worker->pollable_obj != &pollset->pollable_obj) {
+        gpr_mu_lock(&worker->pollable_obj->po.mu);
       }
       if (worker->initialized_cv && worker != pollset->root_worker) {
         if (GRPC_TRACER_ON(grpc_polling_trace)) {
           gpr_log(GPR_DEBUG, "PS:%p kickall_via_cv %p (pollable %p vs %p)",
-                  pollset, worker, &pollset->pollable, worker->pollable);
+                  pollset, worker, &pollset->pollable_obj,
+                  worker->pollable_obj);
         }
         worker->kicked = true;
         gpr_cv_signal(&worker->cv);
       } else {
         if (GRPC_TRACER_ON(grpc_polling_trace)) {
           gpr_log(GPR_DEBUG, "PS:%p kickall_via_wakeup %p (pollable %p vs %p)",
-                  pollset, worker, &pollset->pollable, worker->pollable);
+                  pollset, worker, &pollset->pollable_obj,
+                  worker->pollable_obj);
         }
-        append_error(&error, grpc_wakeup_fd_wakeup(&worker->pollable->wakeup),
+        append_error(&error,
+                     grpc_wakeup_fd_wakeup(&worker->pollable_obj->wakeup),
                      "pollset_shutdown");
       }
-      if (worker->pollable != &pollset->pollable) {
-        gpr_mu_unlock(&worker->pollable->po.mu);
+      if (worker->pollable_obj != &pollset->pollable_obj) {
+        gpr_mu_unlock(&worker->pollable_obj->po.mu);
       }
 
       worker = worker->links[PWL_POLLSET].next;
@@ -589,7 +592,7 @@ static void do_kick_all(grpc_exec_ctx *exec_ctx, void *arg,
   }
   pollset->kick_alls_pending--;
   pollset_maybe_finish_shutdown(exec_ctx, pollset);
-  gpr_mu_unlock(&pollset->pollable.po.mu);
+  gpr_mu_unlock(&pollset->pollable_obj.po.mu);
   GRPC_LOG_IF_ERROR("kick_all", error);
 }
 
@@ -600,8 +603,7 @@ static void pollset_kick_all(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset) {
                      GRPC_ERROR_NONE);
 }
 
-static grpc_error *pollset_kick_inner(grpc_exec_ctx *exec_ctx,
-                                      grpc_pollset *pollset, pollable_t *p,
+static grpc_error *pollset_kick_inner(grpc_pollset *pollset, pollable *p,
                                       grpc_pollset_worker *specific_worker) {
   if (GRPC_TRACER_ON(grpc_polling_trace)) {
     gpr_log(GPR_DEBUG,
@@ -666,25 +668,25 @@ static grpc_error *pollset_kick_inner(grpc_exec_ctx *exec_ctx,
 /* p->po.mu must be held before calling this function */
 static grpc_error *pollset_kick(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset,
                                 grpc_pollset_worker *specific_worker) {
-  pollable_t *p = pollset->current_pollable;
+  pollable *p = pollset->current_pollable_obj;
   GRPC_STATS_INC_POLLSET_KICK(exec_ctx);
-  if (p != &pollset->pollable) {
+  if (p != &pollset->pollable_obj) {
     gpr_mu_lock(&p->po.mu);
   }
-  grpc_error *error = pollset_kick_inner(exec_ctx, pollset, p, specific_worker);
-  if (p != &pollset->pollable) {
+  grpc_error *error = pollset_kick_inner(pollset, p, specific_worker);
+  if (p != &pollset->pollable_obj) {
     gpr_mu_unlock(&p->po.mu);
   }
   return error;
 }
 
 static void pollset_init(grpc_pollset *pollset, gpr_mu **mu) {
-  pollable_init(&pollset->pollable, PO_POLLSET);
-  pollset->current_pollable = &g_empty_pollable;
+  pollable_init(&pollset->pollable_obj, PO_POLLSET);
+  pollset->current_pollable_obj = &g_empty_pollable;
   pollset->kicked_without_poller = false;
   pollset->shutdown_closure = NULL;
   pollset->root_worker = NULL;
-  *mu = &pollset->pollable.po.mu;
+  *mu = &pollset->pollable_obj.po.mu;
 }
 
 /* Convert a timespec to milliseconds:
@@ -732,8 +734,8 @@ static void fd_become_writable(grpc_exec_ctx *exec_ctx, grpc_fd *fd) {
 static grpc_error *fd_become_pollable_locked(grpc_fd *fd) {
   grpc_error *error = GRPC_ERROR_NONE;
   static const char *err_desc = "fd_become_pollable";
-  if (append_error(&error, pollable_materialize(&fd->pollable), err_desc)) {
-    append_error(&error, pollable_add_fd(&fd->pollable, fd), err_desc);
+  if (append_error(&error, pollable_materialize(&fd->pollable_obj), err_desc)) {
+    append_error(&error, pollable_add_fd(&fd->pollable_obj, fd), err_desc);
   }
   return error;
 }
@@ -747,8 +749,8 @@ static void pollset_shutdown(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset,
   pollset_maybe_finish_shutdown(exec_ctx, pollset);
 }
 
-static bool pollset_is_pollable_fd(grpc_pollset *pollset, pollable_t *p) {
-  return p != &g_empty_pollable && p != &pollset->pollable;
+static bool pollset_is_pollable_fd(grpc_pollset *pollset, pollable *p) {
+  return p != &g_empty_pollable && p != &pollset->pollable_obj;
 }
 
 static grpc_error *pollset_process_events(grpc_exec_ctx *exec_ctx,
@@ -794,9 +796,9 @@ static grpc_error *pollset_process_events(grpc_exec_ctx *exec_ctx,
 
 /* pollset_shutdown is guaranteed to be called before pollset_destroy. */
 static void pollset_destroy(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset) {
-  pollable_destroy(&pollset->pollable);
-  if (pollset_is_pollable_fd(pollset, pollset->current_pollable)) {
-    UNREF_BY(exec_ctx, (grpc_fd *)pollset->current_pollable, 2,
+  pollable_destroy(&pollset->pollable_obj);
+  if (pollset_is_pollable_fd(pollset, pollset->current_pollable_obj)) {
+    UNREF_BY(exec_ctx, (grpc_fd *)pollset->current_pollable_obj, 2,
              "pollset_pollable");
   }
   GRPC_LOG_IF_ERROR("pollset_process_events",
@@ -804,7 +806,7 @@ static void pollset_destroy(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset) {
 }
 
 static grpc_error *pollset_epoll(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset,
-                                 pollable_t *p, gpr_timespec now,
+                                 pollable *p, gpr_timespec now,
                                  gpr_timespec deadline) {
   int timeout = poll_deadline_to_millis_timeout(deadline, now);
 
@@ -886,68 +888,69 @@ static bool begin_worker(grpc_pollset *pollset, grpc_pollset_worker *worker,
   worker->initialized_cv = false;
   worker->kicked = false;
   worker->pollset = pollset;
-  worker->pollable = pollset->current_pollable;
+  worker->pollable_obj = pollset->current_pollable_obj;
 
-  if (pollset_is_pollable_fd(pollset, worker->pollable)) {
-    REF_BY((grpc_fd *)worker->pollable, 2, "one_poll");
+  if (pollset_is_pollable_fd(pollset, worker->pollable_obj)) {
+    REF_BY((grpc_fd *)worker->pollable_obj, 2, "one_poll");
   }
 
   worker_insert(&pollset->root_worker, PWL_POLLSET, worker);
-  if (!worker_insert(&worker->pollable->root_worker, PWL_POLLABLE, worker)) {
+  if (!worker_insert(&worker->pollable_obj->root_worker, PWL_POLLABLE,
+                     worker)) {
     worker->initialized_cv = true;
     gpr_cv_init(&worker->cv);
-    if (worker->pollable != &pollset->pollable) {
-      gpr_mu_unlock(&pollset->pollable.po.mu);
+    if (worker->pollable_obj != &pollset->pollable_obj) {
+      gpr_mu_unlock(&pollset->pollable_obj.po.mu);
     }
     if (GRPC_TRACER_ON(grpc_polling_trace) &&
-        worker->pollable->root_worker != worker) {
+        worker->pollable_obj->root_worker != worker) {
       gpr_log(GPR_DEBUG, "PS:%p wait %p w=%p for %dms", pollset,
-              worker->pollable, worker,
+              worker->pollable_obj, worker,
               poll_deadline_to_millis_timeout(deadline, *now));
     }
-    while (do_poll && worker->pollable->root_worker != worker) {
-      if (gpr_cv_wait(&worker->cv, &worker->pollable->po.mu, deadline)) {
+    while (do_poll && worker->pollable_obj->root_worker != worker) {
+      if (gpr_cv_wait(&worker->cv, &worker->pollable_obj->po.mu, deadline)) {
         if (GRPC_TRACER_ON(grpc_polling_trace)) {
           gpr_log(GPR_DEBUG, "PS:%p timeout_wait %p w=%p", pollset,
-                  worker->pollable, worker);
+                  worker->pollable_obj, worker);
         }
         do_poll = false;
       } else if (worker->kicked) {
         if (GRPC_TRACER_ON(grpc_polling_trace)) {
-          gpr_log(GPR_DEBUG, "PS:%p wakeup %p w=%p", pollset, worker->pollable,
-                  worker);
+          gpr_log(GPR_DEBUG, "PS:%p wakeup %p w=%p", pollset,
+                  worker->pollable_obj, worker);
         }
         do_poll = false;
       } else if (GRPC_TRACER_ON(grpc_polling_trace) &&
-                 worker->pollable->root_worker != worker) {
+                 worker->pollable_obj->root_worker != worker) {
         gpr_log(GPR_DEBUG, "PS:%p spurious_wakeup %p w=%p", pollset,
-                worker->pollable, worker);
+                worker->pollable_obj, worker);
       }
     }
-    if (worker->pollable != &pollset->pollable) {
-      gpr_mu_unlock(&worker->pollable->po.mu);
-      gpr_mu_lock(&pollset->pollable.po.mu);
-      gpr_mu_lock(&worker->pollable->po.mu);
+    if (worker->pollable_obj != &pollset->pollable_obj) {
+      gpr_mu_unlock(&worker->pollable_obj->po.mu);
+      gpr_mu_lock(&pollset->pollable_obj.po.mu);
+      gpr_mu_lock(&worker->pollable_obj->po.mu);
     }
     *now = gpr_now(now->clock_type);
   }
 
   return do_poll && pollset->shutdown_closure == NULL &&
-         pollset->current_pollable == worker->pollable;
+         pollset->current_pollable_obj == worker->pollable_obj;
 }
 
 static void end_worker(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset,
                        grpc_pollset_worker *worker,
                        grpc_pollset_worker **worker_hdl) {
   if (NEW_ROOT ==
-      worker_remove(&worker->pollable->root_worker, PWL_POLLABLE, worker)) {
-    gpr_cv_signal(&worker->pollable->root_worker->cv);
+      worker_remove(&worker->pollable_obj->root_worker, PWL_POLLABLE, worker)) {
+    gpr_cv_signal(&worker->pollable_obj->root_worker->cv);
   }
   if (worker->initialized_cv) {
     gpr_cv_destroy(&worker->cv);
   }
-  if (pollset_is_pollable_fd(pollset, worker->pollable)) {
-    UNREF_BY(exec_ctx, (grpc_fd *)worker->pollable, 2, "one_poll");
+  if (pollset_is_pollable_fd(pollset, worker->pollable_obj)) {
+    UNREF_BY(exec_ctx, (grpc_fd *)worker->pollable_obj, 2, "one_poll");
   }
   if (EMPTIED == worker_remove(&pollset->root_worker, PWL_POLLSET, worker)) {
     pollset_maybe_finish_shutdown(exec_ctx, pollset);
@@ -975,41 +978,41 @@ static grpc_error *pollset_work(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset,
     pollset->kicked_without_poller = false;
     return GRPC_ERROR_NONE;
   }
-  if (pollset->current_pollable != &pollset->pollable) {
-    gpr_mu_lock(&pollset->current_pollable->po.mu);
+  if (pollset->current_pollable_obj != &pollset->pollable_obj) {
+    gpr_mu_lock(&pollset->current_pollable_obj->po.mu);
   }
   if (begin_worker(pollset, &worker, worker_hdl, &now, deadline)) {
     gpr_tls_set(&g_current_thread_pollset, (intptr_t)pollset);
     gpr_tls_set(&g_current_thread_worker, (intptr_t)&worker);
     GPR_ASSERT(!pollset->shutdown_closure);
-    append_error(&error, pollable_materialize(worker.pollable), err_desc);
-    if (worker.pollable != &pollset->pollable) {
-      gpr_mu_unlock(&worker.pollable->po.mu);
+    append_error(&error, pollable_materialize(worker.pollable_obj), err_desc);
+    if (worker.pollable_obj != &pollset->pollable_obj) {
+      gpr_mu_unlock(&worker.pollable_obj->po.mu);
     }
-    gpr_mu_unlock(&pollset->pollable.po.mu);
+    gpr_mu_unlock(&pollset->pollable_obj.po.mu);
     if (pollset->event_cursor == pollset->event_count) {
-      append_error(&error, pollset_epoll(exec_ctx, pollset, worker.pollable,
+      append_error(&error, pollset_epoll(exec_ctx, pollset, worker.pollable_obj,
                                          now, deadline),
                    err_desc);
     }
     append_error(&error, pollset_process_events(exec_ctx, pollset, false),
                  err_desc);
-    gpr_mu_lock(&pollset->pollable.po.mu);
-    if (worker.pollable != &pollset->pollable) {
-      gpr_mu_lock(&worker.pollable->po.mu);
+    gpr_mu_lock(&pollset->pollable_obj.po.mu);
+    if (worker.pollable_obj != &pollset->pollable_obj) {
+      gpr_mu_lock(&worker.pollable_obj->po.mu);
     }
     gpr_tls_set(&g_current_thread_pollset, 0);
     gpr_tls_set(&g_current_thread_worker, 0);
     pollset_maybe_finish_shutdown(exec_ctx, pollset);
   }
   end_worker(exec_ctx, pollset, &worker, worker_hdl);
-  if (worker.pollable != &pollset->pollable) {
-    gpr_mu_unlock(&worker.pollable->po.mu);
+  if (worker.pollable_obj != &pollset->pollable_obj) {
+    gpr_mu_unlock(&worker.pollable_obj->po.mu);
   }
   if (grpc_exec_ctx_has_work(exec_ctx)) {
-    gpr_mu_unlock(&pollset->pollable.po.mu);
+    gpr_mu_unlock(&pollset->pollable_obj.po.mu);
     grpc_exec_ctx_flush(exec_ctx);
-    gpr_mu_lock(&pollset->pollable.po.mu);
+    gpr_mu_lock(&pollset->pollable_obj.po.mu);
   }
   return error;
 }
@@ -1026,27 +1029,27 @@ static grpc_error *pollset_add_fd_locked(grpc_exec_ctx *exec_ctx,
                                          bool fd_locked) {
   static const char *err_desc = "pollset_add_fd";
   grpc_error *error = GRPC_ERROR_NONE;
-  if (pollset->current_pollable == &g_empty_pollable) {
+  if (pollset->current_pollable_obj == &g_empty_pollable) {
     if (GRPC_TRACER_ON(grpc_polling_trace)) {
       gpr_log(GPR_DEBUG,
               "PS:%p add fd %p; transition pollable from empty to fd", pollset,
               fd);
     }
-    /* empty pollable --> single fd pollable_t */
+    /* empty pollable --> single fd pollable */
     pollset_kick_all(exec_ctx, pollset);
-    pollset->current_pollable = &fd->pollable;
-    if (!fd_locked) gpr_mu_lock(&fd->pollable.po.mu);
+    pollset->current_pollable_obj = &fd->pollable_obj;
+    if (!fd_locked) gpr_mu_lock(&fd->pollable_obj.po.mu);
     append_error(&error, fd_become_pollable_locked(fd), err_desc);
-    if (!fd_locked) gpr_mu_unlock(&fd->pollable.po.mu);
+    if (!fd_locked) gpr_mu_unlock(&fd->pollable_obj.po.mu);
     REF_BY(fd, 2, "pollset_pollable");
-  } else if (pollset->current_pollable == &pollset->pollable) {
+  } else if (pollset->current_pollable_obj == &pollset->pollable_obj) {
     if (GRPC_TRACER_ON(grpc_polling_trace)) {
       gpr_log(GPR_DEBUG, "PS:%p add fd %p; already multipolling", pollset, fd);
     }
-    append_error(&error, pollable_add_fd(pollset->current_pollable, fd),
+    append_error(&error, pollable_add_fd(pollset->current_pollable_obj, fd),
                  err_desc);
-  } else if (pollset->current_pollable != &fd->pollable) {
-    grpc_fd *had_fd = (grpc_fd *)pollset->current_pollable;
+  } else if (pollset->current_pollable_obj != &fd->pollable_obj) {
+    grpc_fd *had_fd = (grpc_fd *)pollset->current_pollable_obj;
     if (GRPC_TRACER_ON(grpc_polling_trace)) {
       gpr_log(GPR_DEBUG,
               "PS:%p add fd %p; transition pollable from fd %p to multipoller",
@@ -1058,11 +1061,11 @@ static grpc_error *pollset_add_fd_locked(grpc_exec_ctx *exec_ctx,
     grpc_lfev_set_ready(exec_ctx, &had_fd->read_closure, "read");
     grpc_lfev_set_ready(exec_ctx, &had_fd->write_closure, "write");
     pollset_kick_all(exec_ctx, pollset);
-    pollset->current_pollable = &pollset->pollable;
-    if (append_error(&error, pollable_materialize(&pollset->pollable),
+    pollset->current_pollable_obj = &pollset->pollable_obj;
+    if (append_error(&error, pollable_materialize(&pollset->pollable_obj),
                      err_desc)) {
-      pollable_add_fd(&pollset->pollable, had_fd);
-      pollable_add_fd(&pollset->pollable, fd);
+      pollable_add_fd(&pollset->pollable_obj, had_fd);
+      pollable_add_fd(&pollset->pollable_obj, fd);
     }
     GRPC_CLOSURE_SCHED(exec_ctx,
                        GRPC_CLOSURE_CREATE(unref_fd_no_longer_poller, had_fd,
@@ -1074,9 +1077,9 @@ static grpc_error *pollset_add_fd_locked(grpc_exec_ctx *exec_ctx,
 
 static void pollset_add_fd(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset,
                            grpc_fd *fd) {
-  gpr_mu_lock(&pollset->pollable.po.mu);
+  gpr_mu_lock(&pollset->pollable_obj.po.mu);
   grpc_error *error = pollset_add_fd_locked(exec_ctx, pollset, fd, false);
-  gpr_mu_unlock(&pollset->pollable.po.mu);
+  gpr_mu_unlock(&pollset->pollable_obj.po.mu);
   GRPC_LOG_IF_ERROR("pollset_add_fd", error);
 }
 
@@ -1098,7 +1101,7 @@ static void pollset_set_destroy(grpc_exec_ctx *exec_ctx,
 
 static void pollset_set_add_fd(grpc_exec_ctx *exec_ctx, grpc_pollset_set *pss,
                                grpc_fd *fd) {
-  po_join(exec_ctx, &pss->po, &fd->pollable.po);
+  po_join(exec_ctx, &pss->po, &fd->pollable_obj.po);
 }
 
 static void pollset_set_del_fd(grpc_exec_ctx *exec_ctx, grpc_pollset_set *pss,
@@ -1106,7 +1109,7 @@ static void pollset_set_del_fd(grpc_exec_ctx *exec_ctx, grpc_pollset_set *pss,
 
 static void pollset_set_add_pollset(grpc_exec_ctx *exec_ctx,
                                     grpc_pollset_set *pss, grpc_pollset *ps) {
-  po_join(exec_ctx, &pss->po, &ps->pollable.po);
+  po_join(exec_ctx, &pss->po, &ps->pollable_obj.po);
 }
 
 static void pollset_set_del_pollset(grpc_exec_ctx *exec_ctx,
diff --git a/src/core/lib/iomgr/ev_poll_posix.c b/src/core/lib/iomgr/ev_poll_posix.c
index 15968d23ba..b8482b9d3a 100644
--- a/src/core/lib/iomgr/ev_poll_posix.c
+++ b/src/core/lib/iomgr/ev_poll_posix.c
@@ -1543,7 +1543,7 @@ static int cvfd_poll(struct pollfd *fds, nfds_t nfds, int timeout) {
   for (i = 0; i < nfds; i++) {
     fds[i].revents = 0;
     if (fds[i].fd < 0 && (fds[i].events & POLLIN)) {
-      idx = FD_TO_IDX(fds[i].fd);
+      idx = GRPC_FD_TO_IDX(fds[i].fd);
       fd_cvs[i].cv = &pollcv_cv;
       fd_cvs[i].prev = NULL;
       fd_cvs[i].next = g_cvfds.cvfds[idx].cvs;
@@ -1606,8 +1606,8 @@ static int cvfd_poll(struct pollfd *fds, nfds_t nfds, int timeout) {
   idx = 0;
   for (i = 0; i < nfds; i++) {
     if (fds[i].fd < 0 && (fds[i].events & POLLIN)) {
-      remove_cvn(&g_cvfds.cvfds[FD_TO_IDX(fds[i].fd)].cvs, &(fd_cvs[i]));
-      if (g_cvfds.cvfds[FD_TO_IDX(fds[i].fd)].is_set) {
+      remove_cvn(&g_cvfds.cvfds[GRPC_FD_TO_IDX(fds[i].fd)].cvs, &(fd_cvs[i]));
+      if (g_cvfds.cvfds[GRPC_FD_TO_IDX(fds[i].fd)].is_set) {
         fds[i].revents = POLLIN;
         if (res >= 0) res++;
       }
diff --git a/src/core/lib/iomgr/wakeup_fd_cv.c b/src/core/lib/iomgr/wakeup_fd_cv.c
index 5e0b1d1704..268e0175dd 100644
--- a/src/core/lib/iomgr/wakeup_fd_cv.c
+++ b/src/core/lib/iomgr/wakeup_fd_cv.c
@@ -57,7 +57,7 @@ static grpc_error* cv_fd_init(grpc_wakeup_fd* fd_info) {
   g_cvfds.free_fds = g_cvfds.free_fds->next_free;
   g_cvfds.cvfds[idx].cvs = NULL;
   g_cvfds.cvfds[idx].is_set = 0;
-  fd_info->read_fd = IDX_TO_FD(idx);
+  fd_info->read_fd = GRPC_IDX_TO_FD(idx);
   fd_info->write_fd = -1;
   gpr_mu_unlock(&g_cvfds.mu);
   return GRPC_ERROR_NONE;
@@ -66,8 +66,8 @@ static grpc_error* cv_fd_init(grpc_wakeup_fd* fd_info) {
 static grpc_error* cv_fd_wakeup(grpc_wakeup_fd* fd_info) {
   cv_node* cvn;
   gpr_mu_lock(&g_cvfds.mu);
-  g_cvfds.cvfds[FD_TO_IDX(fd_info->read_fd)].is_set = 1;
-  cvn = g_cvfds.cvfds[FD_TO_IDX(fd_info->read_fd)].cvs;
+  g_cvfds.cvfds[GRPC_FD_TO_IDX(fd_info->read_fd)].is_set = 1;
+  cvn = g_cvfds.cvfds[GRPC_FD_TO_IDX(fd_info->read_fd)].cvs;
   while (cvn) {
     gpr_cv_signal(cvn->cv);
     cvn = cvn->next;
@@ -78,7 +78,7 @@ static grpc_error* cv_fd_wakeup(grpc_wakeup_fd* fd_info) {
 
 static grpc_error* cv_fd_consume(grpc_wakeup_fd* fd_info) {
   gpr_mu_lock(&g_cvfds.mu);
-  g_cvfds.cvfds[FD_TO_IDX(fd_info->read_fd)].is_set = 0;
+  g_cvfds.cvfds[GRPC_FD_TO_IDX(fd_info->read_fd)].is_set = 0;
   gpr_mu_unlock(&g_cvfds.mu);
   return GRPC_ERROR_NONE;
 }
@@ -89,9 +89,9 @@ static void cv_fd_destroy(grpc_wakeup_fd* fd_info) {
   }
   gpr_mu_lock(&g_cvfds.mu);
   // Assert that there are no active pollers
-  GPR_ASSERT(!g_cvfds.cvfds[FD_TO_IDX(fd_info->read_fd)].cvs);
-  g_cvfds.cvfds[FD_TO_IDX(fd_info->read_fd)].next_free = g_cvfds.free_fds;
-  g_cvfds.free_fds = &g_cvfds.cvfds[FD_TO_IDX(fd_info->read_fd)];
+  GPR_ASSERT(!g_cvfds.cvfds[GRPC_FD_TO_IDX(fd_info->read_fd)].cvs);
+  g_cvfds.cvfds[GRPC_FD_TO_IDX(fd_info->read_fd)].next_free = g_cvfds.free_fds;
+  g_cvfds.free_fds = &g_cvfds.cvfds[GRPC_FD_TO_IDX(fd_info->read_fd)];
   gpr_mu_unlock(&g_cvfds.mu);
 }
 
diff --git a/src/core/lib/iomgr/wakeup_fd_cv.h b/src/core/lib/iomgr/wakeup_fd_cv.h
index 46e84f5843..dc170ad5b4 100644
--- a/src/core/lib/iomgr/wakeup_fd_cv.h
+++ b/src/core/lib/iomgr/wakeup_fd_cv.h
@@ -37,8 +37,8 @@
 
 #include "src/core/lib/iomgr/ev_posix.h"
 
-#define FD_TO_IDX(fd) (-(fd)-1)
-#define IDX_TO_FD(idx) (-(idx)-1)
+#define GRPC_FD_TO_IDX(fd) (-(fd)-1)
+#define GRPC_IDX_TO_FD(idx) (-(idx)-1)
 
 typedef struct cv_node {
   gpr_cv* cv;
diff --git a/src/core/lib/security/transport/security_handshaker.c b/src/core/lib/security/transport/security_handshaker.c
index 975d599523..3d19605617 100644
--- a/src/core/lib/security/transport/security_handshaker.c
+++ b/src/core/lib/security/transport/security_handshaker.c
@@ -137,7 +137,7 @@ static void on_peer_checked_inner(grpc_exec_ctx *exec_ctx,
   // Create zero-copy frame protector, if implemented.
   tsi_zero_copy_grpc_protector *zero_copy_protector = NULL;
   tsi_result result = tsi_handshaker_result_create_zero_copy_grpc_protector(
-      h->handshaker_result, NULL, &zero_copy_protector);
+      exec_ctx, h->handshaker_result, NULL, &zero_copy_protector);
   if (result != TSI_OK && result != TSI_UNIMPLEMENTED) {
     error = grpc_set_tsi_error_result(
         GRPC_ERROR_CREATE_FROM_STATIC_STRING(
diff --git a/src/core/lib/surface/call.c b/src/core/lib/surface/call.c
index bb5b57a8bc..135257c1ac 100644
--- a/src/core/lib/surface/call.c
+++ b/src/core/lib/surface/call.c
@@ -135,7 +135,7 @@ typedef struct batch_control {
 typedef struct {
   gpr_mu child_list_mu;
   grpc_call *first_child;
-} parent_call_t;
+} parent_call;
 
 typedef struct {
   grpc_call *parent;
@@ -144,7 +144,7 @@ typedef struct {
       parent->mu */
   grpc_call *sibling_next;
   grpc_call *sibling_prev;
-} child_call_t;
+} child_call;
 
 #define RECV_NONE ((gpr_atm)0)
 #define RECV_INITIAL_METADATA_FIRST ((gpr_atm)1)
@@ -157,8 +157,8 @@ struct grpc_call {
   grpc_polling_entity pollent;
   grpc_channel *channel;
   gpr_timespec start_time;
-  /* parent_call_t* */ gpr_atm parent_call_atm;
-  child_call_t *child_call;
+  /* parent_call* */ gpr_atm parent_call_atm;
+  child_call *child;
 
   /* client or server call */
   bool is_client;
@@ -304,21 +304,21 @@ void *grpc_call_arena_alloc(grpc_call *call, size_t size) {
   return gpr_arena_alloc(call->arena, size);
 }
 
-static parent_call_t *get_or_create_parent_call(grpc_call *call) {
-  parent_call_t *p = (parent_call_t *)gpr_atm_acq_load(&call->parent_call_atm);
+static parent_call *get_or_create_parent_call(grpc_call *call) {
+  parent_call *p = (parent_call *)gpr_atm_acq_load(&call->parent_call_atm);
   if (p == NULL) {
-    p = (parent_call_t *)gpr_arena_alloc(call->arena, sizeof(*p));
+    p = (parent_call *)gpr_arena_alloc(call->arena, sizeof(*p));
     gpr_mu_init(&p->child_list_mu);
     if (!gpr_atm_rel_cas(&call->parent_call_atm, (gpr_atm)NULL, (gpr_atm)p)) {
       gpr_mu_destroy(&p->child_list_mu);
-      p = (parent_call_t *)gpr_atm_acq_load(&call->parent_call_atm);
+      p = (parent_call *)gpr_atm_acq_load(&call->parent_call_atm);
     }
   }
   return p;
 }
 
-static parent_call_t *get_parent_call(grpc_call *call) {
-  return (parent_call_t *)gpr_atm_acq_load(&call->parent_call_atm);
+static parent_call *get_parent_call(grpc_call *call) {
+  return (parent_call *)gpr_atm_acq_load(&call->parent_call_atm);
 }
 
 grpc_error *grpc_call_create(grpc_exec_ctx *exec_ctx,
@@ -378,24 +378,24 @@ grpc_error *grpc_call_create(grpc_exec_ctx *exec_ctx,
 
   bool immediately_cancel = false;
 
-  if (args->parent_call != NULL) {
-    child_call_t *cc = call->child_call =
-        (child_call_t *)gpr_arena_alloc(arena, sizeof(child_call_t));
-    call->child_call->parent = args->parent_call;
+  if (args->parent != NULL) {
+    child_call *cc = call->child =
+        (child_call *)gpr_arena_alloc(arena, sizeof(child_call));
+    call->child->parent = args->parent;
 
-    GRPC_CALL_INTERNAL_REF(args->parent_call, "child");
+    GRPC_CALL_INTERNAL_REF(args->parent, "child");
     GPR_ASSERT(call->is_client);
-    GPR_ASSERT(!args->parent_call->is_client);
+    GPR_ASSERT(!args->parent->is_client);
 
-    parent_call_t *pc = get_or_create_parent_call(args->parent_call);
+    parent_call *pc = get_or_create_parent_call(args->parent);
 
     gpr_mu_lock(&pc->child_list_mu);
 
     if (args->propagation_mask & GRPC_PROPAGATE_DEADLINE) {
       send_deadline = gpr_time_min(
           gpr_convert_clock_type(send_deadline,
-                                 args->parent_call->send_deadline.clock_type),
-          args->parent_call->send_deadline);
+                                 args->parent->send_deadline.clock_type),
+          args->parent->send_deadline);
     }
     /* for now GRPC_PROPAGATE_TRACING_CONTEXT *MUST* be passed with
      * GRPC_PROPAGATE_STATS_CONTEXT */
@@ -407,9 +407,9 @@ grpc_error *grpc_call_create(grpc_exec_ctx *exec_ctx,
                                    "Census tracing propagation requested "
                                    "without Census context propagation"));
       }
-      grpc_call_context_set(
-          call, GRPC_CONTEXT_TRACING,
-          args->parent_call->context[GRPC_CONTEXT_TRACING].value, NULL);
+      grpc_call_context_set(call, GRPC_CONTEXT_TRACING,
+                            args->parent->context[GRPC_CONTEXT_TRACING].value,
+                            NULL);
     } else if (args->propagation_mask & GRPC_PROPAGATE_CENSUS_STATS_CONTEXT) {
       add_init_error(&error, GRPC_ERROR_CREATE_FROM_STATIC_STRING(
                                  "Census context propagation requested "
@@ -417,7 +417,7 @@ grpc_error *grpc_call_create(grpc_exec_ctx *exec_ctx,
     }
     if (args->propagation_mask & GRPC_PROPAGATE_CANCELLATION) {
       call->cancellation_is_inherited = 1;
-      if (gpr_atm_acq_load(&args->parent_call->received_final_op_atm)) {
+      if (gpr_atm_acq_load(&args->parent->received_final_op_atm)) {
         immediately_cancel = true;
       }
     }
@@ -427,9 +427,9 @@ grpc_error *grpc_call_create(grpc_exec_ctx *exec_ctx,
       cc->sibling_next = cc->sibling_prev = call;
     } else {
       cc->sibling_next = pc->first_child;
-      cc->sibling_prev = pc->first_child->child_call->sibling_prev;
-      cc->sibling_next->child_call->sibling_prev =
-          cc->sibling_prev->child_call->sibling_next = call;
+      cc->sibling_prev = pc->first_child->child->sibling_prev;
+      cc->sibling_next->child->sibling_prev =
+          cc->sibling_prev->child->sibling_next = call;
     }
 
     gpr_mu_unlock(&pc->child_list_mu);
@@ -534,7 +534,7 @@ static void destroy_call(grpc_exec_ctx *exec_ctx, void *call,
   if (c->receiving_stream != NULL) {
     grpc_byte_stream_destroy(exec_ctx, c->receiving_stream);
   }
-  parent_call_t *pc = get_parent_call(c);
+  parent_call *pc = get_parent_call(c);
   if (pc != NULL) {
     gpr_mu_destroy(&pc->child_list_mu);
   }
@@ -571,14 +571,14 @@ void grpc_call_ref(grpc_call *c) { gpr_ref(&c->ext_ref); }
 void grpc_call_unref(grpc_call *c) {
   if (!gpr_unref(&c->ext_ref)) return;
 
-  child_call_t *cc = c->child_call;
+  child_call *cc = c->child;
   grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
 
   GPR_TIMER_BEGIN("grpc_call_unref", 0);
   GRPC_API_TRACE("grpc_call_unref(c=%p)", 1, (c));
 
   if (cc) {
-    parent_call_t *pc = get_parent_call(cc->parent);
+    parent_call *pc = get_parent_call(cc->parent);
     gpr_mu_lock(&pc->child_list_mu);
     if (c == pc->first_child) {
       pc->first_child = cc->sibling_next;
@@ -586,8 +586,8 @@ void grpc_call_unref(grpc_call *c) {
         pc->first_child = NULL;
       }
     }
-    cc->sibling_prev->child_call->sibling_next = cc->sibling_next;
-    cc->sibling_next->child_call->sibling_prev = cc->sibling_prev;
+    cc->sibling_prev->child->sibling_next = cc->sibling_next;
+    cc->sibling_next->child->sibling_prev = cc->sibling_prev;
     gpr_mu_unlock(&pc->child_list_mu);
     GRPC_CALL_INTERNAL_UNREF(&exec_ctx, cc->parent, "child");
   }
@@ -1310,14 +1310,14 @@ static void post_batch_completion(grpc_exec_ctx *exec_ctx,
 
     /* propagate cancellation to any interested children */
     gpr_atm_rel_store(&call->received_final_op_atm, 1);
-    parent_call_t *pc = get_parent_call(call);
+    parent_call *pc = get_parent_call(call);
     if (pc != NULL) {
       grpc_call *child;
       gpr_mu_lock(&pc->child_list_mu);
       child = pc->first_child;
       if (child != NULL) {
         do {
-          next_child_call = child->child_call->sibling_next;
+          next_child_call = child->child->sibling_next;
           if (child->cancellation_is_inherited) {
             GRPC_CALL_INTERNAL_REF(child, "propagate_cancel");
             cancel_with_error(exec_ctx, child, STATUS_FROM_API_OVERRIDE,
diff --git a/src/core/lib/surface/call.h b/src/core/lib/surface/call.h
index d537637cbb..c680139cf6 100644
--- a/src/core/lib/surface/call.h
+++ b/src/core/lib/surface/call.h
@@ -37,7 +37,7 @@ typedef void (*grpc_ioreq_completion_func)(grpc_exec_ctx *exec_ctx,
 typedef struct grpc_call_create_args {
   grpc_channel *channel;
 
-  grpc_call *parent_call;
+  grpc_call *parent;
   uint32_t propagation_mask;
 
   grpc_completion_queue *cq;
diff --git a/src/core/lib/surface/channel.c b/src/core/lib/surface/channel.c
index 34548dac26..48962e5e45 100644
--- a/src/core/lib/surface/channel.c
+++ b/src/core/lib/surface/channel.c
@@ -27,6 +27,7 @@
 #include <grpc/support/string_util.h>
 
 #include "src/core/lib/channel/channel_args.h"
+#include "src/core/lib/debug/stats.h"
 #include "src/core/lib/iomgr/iomgr.h"
 #include "src/core/lib/slice/slice_internal.h"
 #include "src/core/lib/support/string.h"
@@ -77,6 +78,11 @@ grpc_channel *grpc_channel_create_with_builder(
   grpc_channel_args *args = grpc_channel_args_copy(
       grpc_channel_stack_builder_get_channel_arguments(builder));
   grpc_channel *channel;
+  if (channel_stack_type == GRPC_SERVER_CHANNEL) {
+    GRPC_STATS_INC_SERVER_CHANNELS_CREATED(exec_ctx);
+  } else {
+    GRPC_STATS_INC_CLIENT_CHANNELS_CREATED(exec_ctx);
+  }
   grpc_error *error = grpc_channel_stack_builder_finish(
       exec_ctx, builder, sizeof(grpc_channel), 1, destroy_channel, NULL,
       (void **)&channel);
@@ -276,7 +282,7 @@ static grpc_call *grpc_channel_create_call_internal(
   grpc_call_create_args args;
   memset(&args, 0, sizeof(args));
   args.channel = channel;
-  args.parent_call = parent_call;
+  args.parent = parent_call;
   args.propagation_mask = propagation_mask;
   args.cq = cq;
   args.pollset_set_alternative = pollset_set_alternative;
diff --git a/src/core/lib/surface/completion_queue.c b/src/core/lib/surface/completion_queue.c
index bc57c6136b..13fb6cccf8 100644
--- a/src/core/lib/surface/completion_queue.c
+++ b/src/core/lib/surface/completion_queue.c
@@ -26,6 +26,7 @@
 #include <grpc/support/string_util.h>
 #include <grpc/support/time.h>
 
+#include "src/core/lib/debug/stats.h"
 #include "src/core/lib/iomgr/pollset.h"
 #include "src/core/lib/iomgr/timer.h"
 #include "src/core/lib/profiling/timers.h"
@@ -421,6 +422,10 @@ grpc_completion_queue *grpc_completion_queue_create_internal(
   const cq_poller_vtable *poller_vtable =
       &g_poller_vtable_by_poller_type[polling_type];
 
+  grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
+  GRPC_STATS_INC_CQS_CREATED(&exec_ctx);
+  grpc_exec_ctx_finish(&exec_ctx);
+
   cq = (grpc_completion_queue *)gpr_zalloc(sizeof(grpc_completion_queue) +
                                            vtable->data_size +
                                            poller_vtable->size());
@@ -576,12 +581,12 @@ static bool atm_inc_if_nonzero(gpr_atm *counter) {
 }
 
 static bool cq_begin_op_for_next(grpc_completion_queue *cq, void *tag) {
-  cq_next_data *cqd = DATA_FROM_CQ(cq);
+  cq_next_data *cqd = (cq_next_data *)DATA_FROM_CQ(cq);
   return atm_inc_if_nonzero(&cqd->pending_events);
 }
 
 static bool cq_begin_op_for_pluck(grpc_completion_queue *cq, void *tag) {
-  cq_pluck_data *cqd = DATA_FROM_CQ(cq);
+  cq_pluck_data *cqd = (cq_pluck_data *)DATA_FROM_CQ(cq);
   return atm_inc_if_nonzero(&cqd->pending_events);
 }
 
@@ -626,7 +631,7 @@ static void cq_end_op_for_next(grpc_exec_ctx *exec_ctx,
     }
   }
 
-  cq_next_data *cqd = DATA_FROM_CQ(cq);
+  cq_next_data *cqd = (cq_next_data *)DATA_FROM_CQ(cq);
   int is_success = (error == GRPC_ERROR_NONE);
 
   storage->tag = tag;
@@ -687,7 +692,7 @@ static void cq_end_op_for_pluck(grpc_exec_ctx *exec_ctx,
                                              void *done_arg,
                                              grpc_cq_completion *storage),
                                 void *done_arg, grpc_cq_completion *storage) {
-  cq_pluck_data *cqd = DATA_FROM_CQ(cq);
+  cq_pluck_data *cqd = (cq_pluck_data *)DATA_FROM_CQ(cq);
   int is_success = (error == GRPC_ERROR_NONE);
 
   GPR_TIMER_BEGIN("cq_end_op_for_pluck", 0);
@@ -770,7 +775,7 @@ typedef struct {
 static bool cq_is_next_finished(grpc_exec_ctx *exec_ctx, void *arg) {
   cq_is_finished_arg *a = (cq_is_finished_arg *)arg;
   grpc_completion_queue *cq = a->cq;
-  cq_next_data *cqd = DATA_FROM_CQ(cq);
+  cq_next_data *cqd = (cq_next_data *)DATA_FROM_CQ(cq);
   GPR_ASSERT(a->stolen_completion == NULL);
 
   gpr_atm current_last_seen_things_queued_ever =
@@ -821,7 +826,7 @@ static grpc_event cq_next(grpc_completion_queue *cq, gpr_timespec deadline,
                           void *reserved) {
   grpc_event ret;
   gpr_timespec now;
-  cq_next_data *cqd = DATA_FROM_CQ(cq);
+  cq_next_data *cqd = (cq_next_data *)DATA_FROM_CQ(cq);
 
   GPR_TIMER_BEGIN("grpc_completion_queue_next", 0);
 
@@ -954,7 +959,7 @@ static grpc_event cq_next(grpc_completion_queue *cq, gpr_timespec deadline,
    this function */
 static void cq_finish_shutdown_next(grpc_exec_ctx *exec_ctx,
                                     grpc_completion_queue *cq) {
-  cq_next_data *cqd = DATA_FROM_CQ(cq);
+  cq_next_data *cqd = (cq_next_data *)DATA_FROM_CQ(cq);
 
   GPR_ASSERT(cqd->shutdown_called);
   GPR_ASSERT(gpr_atm_no_barrier_load(&cqd->pending_events) == 0);
@@ -965,7 +970,7 @@ static void cq_finish_shutdown_next(grpc_exec_ctx *exec_ctx,
 
 static void cq_shutdown_next(grpc_exec_ctx *exec_ctx,
                              grpc_completion_queue *cq) {
-  cq_next_data *cqd = DATA_FROM_CQ(cq);
+  cq_next_data *cqd = (cq_next_data *)DATA_FROM_CQ(cq);
 
   /* Need an extra ref for cq here because:
    * We call cq_finish_shutdown_next() below, that would call pollset shutdown.
@@ -995,7 +1000,7 @@ grpc_event grpc_completion_queue_next(grpc_completion_queue *cq,
 
 static int add_plucker(grpc_completion_queue *cq, void *tag,
                        grpc_pollset_worker **worker) {
-  cq_pluck_data *cqd = DATA_FROM_CQ(cq);
+  cq_pluck_data *cqd = (cq_pluck_data *)DATA_FROM_CQ(cq);
   if (cqd->num_pluckers == GRPC_MAX_COMPLETION_QUEUE_PLUCKERS) {
     return 0;
   }
@@ -1007,7 +1012,7 @@ static int add_plucker(grpc_completion_queue *cq, void *tag,
 
 static void del_plucker(grpc_completion_queue *cq, void *tag,
                         grpc_pollset_worker **worker) {
-  cq_pluck_data *cqd = DATA_FROM_CQ(cq);
+  cq_pluck_data *cqd = (cq_pluck_data *)DATA_FROM_CQ(cq);
   for (int i = 0; i < cqd->num_pluckers; i++) {
     if (cqd->pluckers[i].tag == tag && cqd->pluckers[i].worker == worker) {
       cqd->num_pluckers--;
@@ -1021,7 +1026,7 @@ static void del_plucker(grpc_completion_queue *cq, void *tag,
 static bool cq_is_pluck_finished(grpc_exec_ctx *exec_ctx, void *arg) {
   cq_is_finished_arg *a = (cq_is_finished_arg *)arg;
   grpc_completion_queue *cq = a->cq;
-  cq_pluck_data *cqd = DATA_FROM_CQ(cq);
+  cq_pluck_data *cqd = (cq_pluck_data *)DATA_FROM_CQ(cq);
 
   GPR_ASSERT(a->stolen_completion == NULL);
   gpr_atm current_last_seen_things_queued_ever =
@@ -1058,7 +1063,7 @@ static grpc_event cq_pluck(grpc_completion_queue *cq, void *tag,
   grpc_cq_completion *prev;
   grpc_pollset_worker *worker = NULL;
   gpr_timespec now;
-  cq_pluck_data *cqd = DATA_FROM_CQ(cq);
+  cq_pluck_data *cqd = (cq_pluck_data *)DATA_FROM_CQ(cq);
 
   GPR_TIMER_BEGIN("grpc_completion_queue_pluck", 0);
 
@@ -1182,7 +1187,7 @@ grpc_event grpc_completion_queue_pluck(grpc_completion_queue *cq, void *tag,
 
 static void cq_finish_shutdown_pluck(grpc_exec_ctx *exec_ctx,
                                      grpc_completion_queue *cq) {
-  cq_pluck_data *cqd = DATA_FROM_CQ(cq);
+  cq_pluck_data *cqd = (cq_pluck_data *)DATA_FROM_CQ(cq);
 
   GPR_ASSERT(cqd->shutdown_called);
   GPR_ASSERT(!gpr_atm_no_barrier_load(&cqd->shutdown));
@@ -1196,7 +1201,7 @@ static void cq_finish_shutdown_pluck(grpc_exec_ctx *exec_ctx,
  * merging them is a bit tricky and probably not worth it */
 static void cq_shutdown_pluck(grpc_exec_ctx *exec_ctx,
                               grpc_completion_queue *cq) {
-  cq_pluck_data *cqd = DATA_FROM_CQ(cq);
+  cq_pluck_data *cqd = (cq_pluck_data *)DATA_FROM_CQ(cq);
 
   /* Need an extra ref for cq here because:
    * We call cq_finish_shutdown_pluck() below, that would call pollset shutdown.
diff --git a/src/core/lib/surface/init.c b/src/core/lib/surface/init.c
index 280315036f..b089da2c54 100644
--- a/src/core/lib/surface/init.c
+++ b/src/core/lib/surface/init.c
@@ -36,6 +36,7 @@
 #include "src/core/lib/iomgr/executor.h"
 #include "src/core/lib/iomgr/iomgr.h"
 #include "src/core/lib/iomgr/resource_quota.h"
+#include "src/core/lib/iomgr/timer_manager.h"
 #include "src/core/lib/profiling/timers.h"
 #include "src/core/lib/slice/slice_internal.h"
 #include "src/core/lib/surface/alarm_internal.h"
@@ -179,14 +180,16 @@ void grpc_shutdown(void) {
       GRPC_EXEC_CTX_INITIALIZER(0, grpc_never_ready_to_finish, NULL);
   gpr_mu_lock(&g_init_mu);
   if (--g_initializations == 0) {
-    grpc_iomgr_shutdown(&exec_ctx);
-    gpr_timers_global_destroy();
-    grpc_tracer_shutdown();
+    grpc_executor_shutdown(&exec_ctx);
+    grpc_timer_manager_set_threading(false);  // shutdown timer_manager thread
     for (i = g_number_of_plugins; i >= 0; i--) {
       if (g_all_of_the_plugins[i].destroy != NULL) {
         g_all_of_the_plugins[i].destroy();
       }
     }
+    grpc_iomgr_shutdown(&exec_ctx);
+    gpr_timers_global_destroy();
+    grpc_tracer_shutdown();
     grpc_mdctx_global_shutdown(&exec_ctx);
     grpc_handshaker_factory_registry_shutdown(&exec_ctx);
     grpc_slice_intern_shutdown();
diff --git a/src/core/lib/surface/server.c b/src/core/lib/surface/server.c
index 13ecc915ec..1d0fd472d0 100644
--- a/src/core/lib/surface/server.c
+++ b/src/core/lib/surface/server.c
@@ -76,7 +76,7 @@ typedef struct requested_call {
       grpc_call_details *details;
     } batch;
     struct {
-      registered_method *registered_method;
+      registered_method *method;
       gpr_timespec *deadline;
       grpc_byte_buffer **optional_payload;
     } registered;
@@ -145,7 +145,7 @@ struct call_data {
   uint32_t recv_initial_metadata_flags;
   grpc_metadata_array initial_metadata;
 
-  request_matcher *request_matcher;
+  request_matcher *matcher;
   grpc_byte_buffer *payload;
 
   grpc_closure got_initial_metadata;
@@ -171,7 +171,7 @@ struct registered_method {
   grpc_server_register_method_payload_handling payload_handling;
   uint32_t flags;
   /* one request matcher per method */
-  request_matcher request_matcher;
+  request_matcher matcher;
   registered_method *next;
 };
 
@@ -334,7 +334,7 @@ static void request_matcher_destroy(request_matcher *rm) {
 
 static void kill_zombie(grpc_exec_ctx *exec_ctx, void *elem,
                         grpc_error *error) {
-  grpc_call_unref(grpc_call_from_top_element(elem));
+  grpc_call_unref(grpc_call_from_top_element((grpc_call_element *)elem));
 }
 
 static void request_matcher_zombify_all_pending_calls(grpc_exec_ctx *exec_ctx,
@@ -387,7 +387,7 @@ static void server_delete(grpc_exec_ctx *exec_ctx, grpc_server *server) {
   while ((rm = server->registered_methods) != NULL) {
     server->registered_methods = rm->next;
     if (server->started) {
-      request_matcher_destroy(&rm->request_matcher);
+      request_matcher_destroy(&rm->matcher);
     }
     gpr_free(rm->method);
     gpr_free(rm->host);
@@ -519,7 +519,7 @@ static void publish_new_rpc(grpc_exec_ctx *exec_ctx, void *arg,
   grpc_call_element *call_elem = (grpc_call_element *)arg;
   call_data *calld = (call_data *)call_elem->call_data;
   channel_data *chand = (channel_data *)call_elem->channel_data;
-  request_matcher *rm = calld->request_matcher;
+  request_matcher *rm = calld->matcher;
   grpc_server *server = rm->server;
 
   if (error != GRPC_ERROR_NONE || gpr_atm_acq_load(&server->shutdown_flag)) {
@@ -583,7 +583,7 @@ static void finish_start_new_rpc(
     return;
   }
 
-  calld->request_matcher = rm;
+  calld->matcher = rm;
 
   switch (payload_handling) {
     case GRPC_SRM_PAYLOAD_NONE:
@@ -629,7 +629,7 @@ static void start_new_rpc(grpc_exec_ctx *exec_ctx, grpc_call_element *elem) {
         continue;
       }
       finish_start_new_rpc(exec_ctx, server, elem,
-                           &rm->server_registered_method->request_matcher,
+                           &rm->server_registered_method->matcher,
                            rm->server_registered_method->payload_handling);
       return;
     }
@@ -647,7 +647,7 @@ static void start_new_rpc(grpc_exec_ctx *exec_ctx, grpc_call_element *elem) {
         continue;
       }
       finish_start_new_rpc(exec_ctx, server, elem,
-                           &rm->server_registered_method->request_matcher,
+                           &rm->server_registered_method->matcher,
                            rm->server_registered_method->payload_handling);
       return;
     }
@@ -668,7 +668,7 @@ static int num_listeners(grpc_server *server) {
 
 static void done_shutdown_event(grpc_exec_ctx *exec_ctx, void *server,
                                 grpc_cq_completion *completion) {
-  server_unref(exec_ctx, server);
+  server_unref(exec_ctx, (grpc_server *)server);
 }
 
 static int num_channels(grpc_server *server) {
@@ -691,9 +691,9 @@ static void kill_pending_work_locked(grpc_exec_ctx *exec_ctx,
         exec_ctx, &server->unregistered_request_matcher);
     for (registered_method *rm = server->registered_methods; rm;
          rm = rm->next) {
-      request_matcher_kill_requests(exec_ctx, server, &rm->request_matcher,
+      request_matcher_kill_requests(exec_ctx, server, &rm->matcher,
                                     GRPC_ERROR_REF(error));
-      request_matcher_zombify_all_pending_calls(exec_ctx, &rm->request_matcher);
+      request_matcher_zombify_all_pending_calls(exec_ctx, &rm->matcher);
     }
   }
   GRPC_ERROR_UNREF(error);
@@ -1114,7 +1114,7 @@ void grpc_server_start(grpc_server *server) {
   request_matcher_init(&server->unregistered_request_matcher,
                        (size_t)server->max_requested_calls_per_cq, server);
   for (registered_method *rm = server->registered_methods; rm; rm = rm->next) {
-    request_matcher_init(&rm->request_matcher,
+    request_matcher_init(&rm->matcher,
                          (size_t)server->max_requested_calls_per_cq, server);
   }
 
@@ -1267,8 +1267,9 @@ void grpc_server_shutdown_and_notify(grpc_server *server,
   /* stay locked, and gather up some stuff to do */
   GPR_ASSERT(grpc_cq_begin_op(cq, tag));
   if (server->shutdown_published) {
-    grpc_cq_end_op(&exec_ctx, cq, tag, GRPC_ERROR_NONE, done_published_shutdown,
-                   NULL, gpr_malloc(sizeof(grpc_cq_completion)));
+    grpc_cq_end_op(
+        &exec_ctx, cq, tag, GRPC_ERROR_NONE, done_published_shutdown, NULL,
+        (grpc_cq_completion *)gpr_malloc(sizeof(grpc_cq_completion)));
     gpr_mu_unlock(&server->mu_global);
     goto done;
   }
@@ -1390,7 +1391,7 @@ static grpc_call_error queue_call_request(grpc_exec_ctx *exec_ctx,
       rm = &server->unregistered_request_matcher;
       break;
     case REGISTERED_CALL:
-      rm = &rc->data.registered.registered_method->request_matcher;
+      rm = &rc->data.registered.method->matcher;
       break;
   }
   server->requested_calls_per_cq[cq_idx][request_id] = *rc;
@@ -1519,7 +1520,7 @@ grpc_call_error grpc_server_request_registered_call(
   rc->tag = tag;
   rc->cq_bound_to_call = cq_bound_to_call;
   rc->call = call;
-  rc->data.registered.registered_method = rm;
+  rc->data.registered.method = rm;
   rc->data.registered.deadline = deadline;
   rc->initial_metadata = initial_metadata;
   rc->data.registered.optional_payload = optional_payload;
diff --git a/src/core/lib/transport/metadata_batch.c b/src/core/lib/transport/metadata_batch.c
index a077052561..54388bdcda 100644
--- a/src/core/lib/transport/metadata_batch.c
+++ b/src/core/lib/transport/metadata_batch.c
@@ -233,32 +233,32 @@ void grpc_metadata_batch_remove(grpc_exec_ctx *exec_ctx,
 void grpc_metadata_batch_set_value(grpc_exec_ctx *exec_ctx,
                                    grpc_linked_mdelem *storage,
                                    grpc_slice value) {
-  grpc_mdelem old = storage->md;
-  grpc_mdelem new = grpc_mdelem_from_slices(
-      exec_ctx, grpc_slice_ref_internal(GRPC_MDKEY(old)), value);
-  storage->md = new;
-  GRPC_MDELEM_UNREF(exec_ctx, old);
+  grpc_mdelem old_mdelem = storage->md;
+  grpc_mdelem new_mdelem = grpc_mdelem_from_slices(
+      exec_ctx, grpc_slice_ref_internal(GRPC_MDKEY(old_mdelem)), value);
+  storage->md = new_mdelem;
+  GRPC_MDELEM_UNREF(exec_ctx, old_mdelem);
 }
 
 grpc_error *grpc_metadata_batch_substitute(grpc_exec_ctx *exec_ctx,
                                            grpc_metadata_batch *batch,
                                            grpc_linked_mdelem *storage,
-                                           grpc_mdelem new) {
+                                           grpc_mdelem new_mdelem) {
   assert_valid_callouts(exec_ctx, batch);
   grpc_error *error = GRPC_ERROR_NONE;
-  grpc_mdelem old = storage->md;
-  if (!grpc_slice_eq(GRPC_MDKEY(new), GRPC_MDKEY(old))) {
+  grpc_mdelem old_mdelem = storage->md;
+  if (!grpc_slice_eq(GRPC_MDKEY(new_mdelem), GRPC_MDKEY(old_mdelem))) {
     maybe_unlink_callout(batch, storage);
-    storage->md = new;
+    storage->md = new_mdelem;
     error = maybe_link_callout(batch, storage);
     if (error != GRPC_ERROR_NONE) {
       unlink_storage(&batch->list, storage);
       GRPC_MDELEM_UNREF(exec_ctx, storage->md);
     }
   } else {
-    storage->md = new;
+    storage->md = new_mdelem;
   }
-  GRPC_MDELEM_UNREF(exec_ctx, old);
+  GRPC_MDELEM_UNREF(exec_ctx, old_mdelem);
   assert_valid_callouts(exec_ctx, batch);
   return error;
 }
@@ -302,12 +302,12 @@ grpc_error *grpc_metadata_batch_filter(grpc_exec_ctx *exec_ctx,
   grpc_error *error = GRPC_ERROR_NONE;
   while (l) {
     grpc_linked_mdelem *next = l->next;
-    grpc_filtered_mdelem new = func(exec_ctx, user_data, l->md);
-    add_error(&error, new.error, composite_error_string);
-    if (GRPC_MDISNULL(new.md)) {
+    grpc_filtered_mdelem new_mdelem = func(exec_ctx, user_data, l->md);
+    add_error(&error, new_mdelem.error, composite_error_string);
+    if (GRPC_MDISNULL(new_mdelem.md)) {
       grpc_metadata_batch_remove(exec_ctx, batch, l);
-    } else if (new.md.payload != l->md.payload) {
-      grpc_metadata_batch_substitute(exec_ctx, batch, l, new.md);
+    } else if (new_mdelem.md.payload != l->md.payload) {
+      grpc_metadata_batch_substitute(exec_ctx, batch, l, new_mdelem.md);
     }
     l = next;
   }
diff --git a/src/core/lib/transport/transport.c b/src/core/lib/transport/transport.c
index caa11a956e..ae705195f3 100644
--- a/src/core/lib/transport/transport.c
+++ b/src/core/lib/transport/transport.c
@@ -102,8 +102,9 @@ static void slice_stream_unref(grpc_exec_ctx *exec_ctx, void *p) {
 grpc_slice grpc_slice_from_stream_owned_buffer(grpc_stream_refcount *refcount,
                                                void *buffer, size_t length) {
   slice_stream_ref(&refcount->slice_refcount);
-  return (grpc_slice){.refcount = &refcount->slice_refcount,
-                      .data.refcounted = {.bytes = buffer, .length = length}};
+  return (grpc_slice){
+      .refcount = &refcount->slice_refcount,
+      .data.refcounted = {.bytes = (uint8_t *)buffer, .length = length}};
 }
 
 static const grpc_slice_refcount_vtable stream_ref_slice_vtable = {
diff --git a/src/core/tsi/fake_transport_security.c b/src/core/tsi/fake_transport_security.c
index e7b3be3d86..64043fea08 100644
--- a/src/core/tsi/fake_transport_security.c
+++ b/src/core/tsi/fake_transport_security.c
@@ -493,7 +493,8 @@ static tsi_result fake_handshaker_result_extract_peer(
 }
 
 static tsi_result fake_handshaker_result_create_zero_copy_grpc_protector(
-    const tsi_handshaker_result *self, size_t *max_output_protected_frame_size,
+    void *exec_ctx, const tsi_handshaker_result *self,
+    size_t *max_output_protected_frame_size,
     tsi_zero_copy_grpc_protector **protector) {
   *protector =
       tsi_create_fake_zero_copy_grpc_protector(max_output_protected_frame_size);
diff --git a/src/core/tsi/transport_security.h b/src/core/tsi/transport_security.h
index b0d7039850..3bba38149c 100644
--- a/src/core/tsi/transport_security.h
+++ b/src/core/tsi/transport_security.h
@@ -84,11 +84,17 @@ struct tsi_handshaker {
 };
 
 /* Base for tsi_handshaker_result implementations.
-   See transport_security_interface.h for documentation. */
+   See transport_security_interface.h for documentation.
+   The exec_ctx parameter in create_zero_copy_grpc_protector is supposed to be
+   of type grpc_exec_ctx*, but we're using void* instead to avoid making the TSI
+   API depend on grpc. The create_zero_copy_grpc_protector() method is only used
+   in grpc, where we do need the exec_ctx passed through, but the API still
+   needs to compile in other applications, where grpc_exec_ctx is not defined.
+*/
 typedef struct {
   tsi_result (*extract_peer)(const tsi_handshaker_result *self, tsi_peer *peer);
   tsi_result (*create_zero_copy_grpc_protector)(
-      const tsi_handshaker_result *self,
+      void *exec_ctx, const tsi_handshaker_result *self,
       size_t *max_output_protected_frame_size,
       tsi_zero_copy_grpc_protector **protector);
   tsi_result (*create_frame_protector)(const tsi_handshaker_result *self,
diff --git a/src/core/tsi/transport_security_grpc.c b/src/core/tsi/transport_security_grpc.c
index 773b35e717..affd995230 100644
--- a/src/core/tsi/transport_security_grpc.c
+++ b/src/core/tsi/transport_security_grpc.c
@@ -20,16 +20,18 @@
 
 /* This method creates a tsi_zero_copy_grpc_protector object.  */
 tsi_result tsi_handshaker_result_create_zero_copy_grpc_protector(
-    const tsi_handshaker_result *self, size_t *max_output_protected_frame_size,
+    grpc_exec_ctx *exec_ctx, const tsi_handshaker_result *self,
+    size_t *max_output_protected_frame_size,
     tsi_zero_copy_grpc_protector **protector) {
-  if (self == NULL || self->vtable == NULL || protector == NULL) {
+  if (exec_ctx == NULL || self == NULL || self->vtable == NULL ||
+      protector == NULL) {
     return TSI_INVALID_ARGUMENT;
   }
   if (self->vtable->create_zero_copy_grpc_protector == NULL) {
     return TSI_UNIMPLEMENTED;
   }
   return self->vtable->create_zero_copy_grpc_protector(
-      self, max_output_protected_frame_size, protector);
+      exec_ctx, self, max_output_protected_frame_size, protector);
 }
 
 /* --- tsi_zero_copy_grpc_protector common implementation. ---
diff --git a/src/core/tsi/transport_security_grpc.h b/src/core/tsi/transport_security_grpc.h
index 375a758888..ca6755c12f 100644
--- a/src/core/tsi/transport_security_grpc.h
+++ b/src/core/tsi/transport_security_grpc.h
@@ -30,7 +30,8 @@ extern "C" {
    assuming there is no fatal error.
    The caller is responsible for destroying the protector.  */
 tsi_result tsi_handshaker_result_create_zero_copy_grpc_protector(
-    const tsi_handshaker_result *self, size_t *max_output_protected_frame_size,
+    grpc_exec_ctx *exec_ctx, const tsi_handshaker_result *self,
+    size_t *max_output_protected_frame_size,
     tsi_zero_copy_grpc_protector **protector);
 
 /* -- tsi_zero_copy_grpc_protector object --  */
diff --git a/src/cpp/client/generic_stub.cc b/src/cpp/client/generic_stub.cc
index 66b1ef0e39..de2e449fe8 100644
--- a/src/cpp/client/generic_stub.cc
+++ b/src/cpp/client/generic_stub.cc
@@ -22,14 +22,29 @@
 
 namespace grpc {
 
+namespace {
+std::unique_ptr<GenericClientAsyncReaderWriter> CallInternal(
+    ChannelInterface* channel, ClientContext* context,
+    const grpc::string& method, CompletionQueue* cq, bool start, void* tag) {
+  return std::unique_ptr<GenericClientAsyncReaderWriter>(
+      GenericClientAsyncReaderWriter::Create(
+          channel, cq, RpcMethod(method.c_str(), RpcMethod::BIDI_STREAMING),
+          context, start, tag));
+}
+
+}  // namespace
+
 // begin a call to a named method
 std::unique_ptr<GenericClientAsyncReaderWriter> GenericStub::Call(
     ClientContext* context, const grpc::string& method, CompletionQueue* cq,
     void* tag) {
-  return std::unique_ptr<GenericClientAsyncReaderWriter>(
-      GenericClientAsyncReaderWriter::Create(
-          channel_.get(), cq,
-          RpcMethod(method.c_str(), RpcMethod::BIDI_STREAMING), context, tag));
+  return CallInternal(channel_.get(), context, method, cq, true, tag);
+}
+
+// setup a call to a named method
+std::unique_ptr<GenericClientAsyncReaderWriter> GenericStub::PrepareCall(
+    ClientContext* context, const grpc::string& method, CompletionQueue* cq) {
+  return CallInternal(channel_.get(), context, method, cq, false, nullptr);
 }
 
 }  // namespace grpc
diff --git a/src/cpp/common/channel_arguments.cc b/src/cpp/common/channel_arguments.cc
index f89f5f1f03..f130aecd4b 100644
--- a/src/cpp/common/channel_arguments.cc
+++ b/src/cpp/common/channel_arguments.cc
@@ -86,10 +86,6 @@ void ChannelArguments::SetCompressionAlgorithm(
   SetInt(GRPC_COMPRESSION_CHANNEL_DEFAULT_ALGORITHM, algorithm);
 }
 
-void ChannelArguments::SetGrpclbFallbackTimeout(int fallback_timeout) {
-  SetInt(GRPC_ARG_GRPCLB_FALLBACK_TIMEOUT_MS, fallback_timeout);
-}
-
 void ChannelArguments::SetSocketMutator(grpc_socket_mutator* mutator) {
   if (!mutator) {
     return;
diff --git a/src/objective-c/GRPCClient/GRPCCall.h b/src/objective-c/GRPCClient/GRPCCall.h
index 4d90cfd384..df563ca36c 100644
--- a/src/objective-c/GRPCClient/GRPCCall.h
+++ b/src/objective-c/GRPCClient/GRPCCall.h
@@ -170,6 +170,13 @@ extern id const kGRPCTrailersKey;
 @property (atomic, copy, readwrite) NSString *serverName;
 
 /**
+ * The timeout for the RPC call in seconds. If set to 0, the call will not timeout. If set to
+ * positive, the gRPC call returns with status GRPCErrorCodeDeadlineExceeded if it is not completed
+ * within \a timeout seconds. A negative value is not allowed.
+ */
+@property NSTimeInterval timeout;
+
+/**
  * The container of the request headers of an RPC conforms to this protocol, which is a subset of
  * NSMutableDictionary's interface. It will become a NSMutableDictionary later on.
  * The keys of this container are the header names, which per the HTTP standard are case-
diff --git a/src/objective-c/GRPCClient/GRPCCall.m b/src/objective-c/GRPCClient/GRPCCall.m
index 436c19e354..d6c3a3c165 100644
--- a/src/objective-c/GRPCClient/GRPCCall.m
+++ b/src/objective-c/GRPCClient/GRPCCall.m
@@ -423,7 +423,8 @@ static NSString * const kBearerPrefix = @"Bearer ";
 
   _wrappedCall = [[GRPCWrappedCall alloc] initWithHost:_host
                                             serverName:_serverName
-                                                  path:_path];
+                                                  path:_path
+                                               timeout:_timeout];
   NSAssert(_wrappedCall, @"Error allocating RPC objects. Low memory?");
 
   [self sendHeaders:_requestHeaders];
diff --git a/src/objective-c/GRPCClient/private/GRPCChannel.h b/src/objective-c/GRPCClient/private/GRPCChannel.h
index e2aa5bd036..d37182f754 100644
--- a/src/objective-c/GRPCClient/private/GRPCChannel.h
+++ b/src/objective-c/GRPCClient/private/GRPCChannel.h
@@ -63,5 +63,6 @@ struct grpc_channel_credentials;
 
 - (nullable grpc_call *)unmanagedCallWithPath:(nonnull NSString *)path
                                    serverName:(nonnull NSString *)serverName
+                                      timeout:(NSTimeInterval)timeout
                               completionQueue:(nonnull GRPCCompletionQueue *)queue;
 @end
diff --git a/src/objective-c/GRPCClient/private/GRPCChannel.m b/src/objective-c/GRPCClient/private/GRPCChannel.m
index 52dbc70b99..b78b14f2af 100644
--- a/src/objective-c/GRPCClient/private/GRPCChannel.m
+++ b/src/objective-c/GRPCClient/private/GRPCChannel.m
@@ -182,18 +182,28 @@ static grpc_channel_args *BuildChannelArgs(NSDictionary *dictionary) {
 
 - (grpc_call *)unmanagedCallWithPath:(NSString *)path
                           serverName:(NSString *)serverName
+                             timeout:(NSTimeInterval)timeout
                      completionQueue:(GRPCCompletionQueue *)queue {
+  GPR_ASSERT(timeout >= 0);
+  if (timeout < 0) {
+    timeout = 0;
+  }
   grpc_slice host_slice;
   if (serverName) {
     host_slice = grpc_slice_from_copied_string(serverName.UTF8String);
   }
   grpc_slice path_slice = grpc_slice_from_copied_string(path.UTF8String);
+  gpr_timespec deadline_ms = timeout == 0 ?
+                                gpr_inf_future(GPR_CLOCK_REALTIME) :
+                                gpr_time_add(
+                                    gpr_now(GPR_CLOCK_MONOTONIC),
+                                    gpr_time_from_millis((int64_t)(timeout * 1000), GPR_TIMESPAN));
   grpc_call *call = grpc_channel_create_call(_unmanagedChannel,
                                              NULL, GRPC_PROPAGATE_DEFAULTS,
                                              queue.unmanagedQueue,
                                              path_slice,
                                              serverName ? &host_slice : NULL,
-                                             gpr_inf_future(GPR_CLOCK_REALTIME), NULL);
+                                             deadline_ms, NULL);
   if (serverName) {
     grpc_slice_unref(host_slice);
   }
diff --git a/src/objective-c/GRPCClient/private/GRPCHost.h b/src/objective-c/GRPCClient/private/GRPCHost.h
index 0c1d715240..58171211b0 100644
--- a/src/objective-c/GRPCClient/private/GRPCHost.h
+++ b/src/objective-c/GRPCClient/private/GRPCHost.h
@@ -55,6 +55,7 @@ struct grpc_channel_credentials;
 /** Create a grpc_call object to the provided path on this host. */
 - (nullable struct grpc_call *)unmanagedCallWithPath:(NSString *)path
                                           serverName:(NSString *)serverName
+                                             timeout:(NSTimeInterval)timeout
                                      completionQueue:(GRPCCompletionQueue *)queue;
 
 // TODO: There's a race when a new RPC is coming through just as an existing one is getting
diff --git a/src/objective-c/GRPCClient/private/GRPCHost.m b/src/objective-c/GRPCClient/private/GRPCHost.m
index 23794c1fed..f73e9cbc50 100644
--- a/src/objective-c/GRPCClient/private/GRPCHost.m
+++ b/src/objective-c/GRPCClient/private/GRPCHost.m
@@ -121,6 +121,7 @@ static GRPCConnectivityMonitor *connectivityMonitor = nil;
 
 - (nullable grpc_call *)unmanagedCallWithPath:(NSString *)path
                                    serverName:(NSString *)serverName
+                                      timeout:(NSTimeInterval)timeout
                               completionQueue:(GRPCCompletionQueue *)queue {
   GRPCChannel *channel;
   // This is racing -[GRPCHost disconnect].
@@ -130,7 +131,10 @@ static GRPCConnectivityMonitor *connectivityMonitor = nil;
     }
     channel = _channel;
   }
-  return [channel unmanagedCallWithPath:path serverName:serverName completionQueue:queue];
+  return [channel unmanagedCallWithPath:path
+                             serverName:serverName
+                                timeout:timeout
+                        completionQueue:queue];
 }
 
 - (BOOL)setTLSPEMRootCerts:(nullable NSString *)pemRootCerts
diff --git a/src/objective-c/GRPCClient/private/GRPCWrappedCall.h b/src/objective-c/GRPCClient/private/GRPCWrappedCall.h
index 64075591a3..1cd9da8f3e 100644
--- a/src/objective-c/GRPCClient/private/GRPCWrappedCall.h
+++ b/src/objective-c/GRPCClient/private/GRPCWrappedCall.h
@@ -76,7 +76,8 @@
 
 - (instancetype)initWithHost:(NSString *)host
                   serverName:(NSString *)serverName
-                        path:(NSString *)path NS_DESIGNATED_INITIALIZER;
+                        path:(NSString *)path
+                     timeout:(NSTimeInterval)timeout NS_DESIGNATED_INITIALIZER;
 
 - (void)startBatchWithOperations:(NSArray *)ops errorHandler:(void(^)())errorHandler;
 
diff --git a/src/objective-c/GRPCClient/private/GRPCWrappedCall.m b/src/objective-c/GRPCClient/private/GRPCWrappedCall.m
index 87dc33af88..b0b1223b64 100644
--- a/src/objective-c/GRPCClient/private/GRPCWrappedCall.m
+++ b/src/objective-c/GRPCClient/private/GRPCWrappedCall.m
@@ -238,12 +238,13 @@
 }
 
 - (instancetype)init {
-  return [self initWithHost:nil serverName:nil path:nil];
+  return [self initWithHost:nil serverName:nil path:nil timeout:0];
 }
 
 - (instancetype)initWithHost:(NSString *)host
                   serverName:(NSString *)serverName
-                        path:(NSString *)path {
+                        path:(NSString *)path
+                     timeout:(NSTimeInterval)timeout {
   if (!path || !host) {
     [NSException raise:NSInvalidArgumentException
                 format:@"path and host cannot be nil."];
@@ -255,7 +256,10 @@
     // queue. Currently we use a singleton queue.
     _queue = [GRPCCompletionQueue completionQueue];
 
-    _call = [[GRPCHost hostWithAddress:host] unmanagedCallWithPath:path serverName:serverName completionQueue:_queue];
+    _call = [[GRPCHost hostWithAddress:host] unmanagedCallWithPath:path
+                                                        serverName:serverName
+                                                           timeout:timeout
+                                                   completionQueue:_queue];
     if (_call == NULL) {
       return nil;
     }
diff --git a/src/objective-c/tests/GRPCClientTests.m b/src/objective-c/tests/GRPCClientTests.m
index 9afe507121..82ac2600fa 100644
--- a/src/objective-c/tests/GRPCClientTests.m
+++ b/src/objective-c/tests/GRPCClientTests.m
@@ -28,6 +28,7 @@
 #import <RemoteTest/Messages.pbobjc.h>
 #import <RxLibrary/GRXWriteable.h>
 #import <RxLibrary/GRXWriter+Immediate.h>
+#import <RxLibrary/GRXBufferedPipe.h>
 
 #define TEST_TIMEOUT 16
 
@@ -39,6 +40,7 @@ static NSString * const kRemoteSSLHost = @"grpc-test.sandbox.googleapis.com";
 static GRPCProtoMethod *kInexistentMethod;
 static GRPCProtoMethod *kEmptyCallMethod;
 static GRPCProtoMethod *kUnaryCallMethod;
+static GRPCProtoMethod *kFullDuplexCallMethod;
 
 /** Observer class for testing that responseMetadata is KVO-compliant */
 @interface PassthroughObserver : NSObject
@@ -106,6 +108,9 @@ static GRPCProtoMethod *kUnaryCallMethod;
   kUnaryCallMethod = [[GRPCProtoMethod alloc] initWithPackage:kPackage
                                                       service:kService
                                                        method:@"UnaryCall"];
+  kFullDuplexCallMethod = [[GRPCProtoMethod alloc] initWithPackage:kPackage
+                                                           service:kService
+                                                            method:@"FullDuplexCall"];
 }
 
 - (void)testConnectionToRemoteServer {
@@ -422,4 +427,26 @@ static GRPCProtoMethod *kUnaryCallMethod;
   [self waitForExpectationsWithTimeout:TEST_TIMEOUT handler:nil];
 }
 
+- (void)testTimeout {
+  __weak XCTestExpectation *completion = [self expectationWithDescription:@"RPC completed."];
+
+  GRXBufferedPipe *pipe = [GRXBufferedPipe pipe];
+  GRPCCall *call = [[GRPCCall alloc] initWithHost:kHostAddress
+                                             path:kFullDuplexCallMethod.HTTPPath
+                                   requestsWriter:pipe];
+
+  id<GRXWriteable> responsesWriteable = [[GRXWriteable alloc] initWithValueHandler:^(NSData *value) {
+    XCTAssert(0, @"Failure: response received; Expect: no response received.");
+  } completionHandler:^(NSError *errorOrNil) {
+    XCTAssertNotNil(errorOrNil, @"Failure: no error received; Expect: receive deadline exceeded.");
+    XCTAssertEqual(errorOrNil.code, GRPCErrorCodeDeadlineExceeded);
+    [completion fulfill];
+  }];
+
+  call.timeout = 0.001;
+  [call startWithWriteable:responsesWriteable];
+
+  [self waitForExpectationsWithTimeout:TEST_TIMEOUT handler:nil];
+}
+
 @end
diff --git a/src/objective-c/tests/run_tests.sh b/src/objective-c/tests/run_tests.sh
index 5b7a2d104a..608ae6884b 100755
--- a/src/objective-c/tests/run_tests.sh
+++ b/src/objective-c/tests/run_tests.sh
@@ -49,7 +49,8 @@ xcodebuild \
     HOST_PORT_REMOTE=grpc-test.sandbox.googleapis.com \
     test \
     | egrep -v "$XCODEBUILD_FILTER" \
-    | egrep -v '^$' -
+    | egrep -v '^$' \
+    | egrep -v "(GPBDictionary|GPBArray)" -
 
 echo "TIME:  $(date)"
 xcodebuild \
@@ -57,7 +58,8 @@ xcodebuild \
     -scheme CoreCronetEnd2EndTests \
     -destination name="iPhone 6" \
     test \
-    | egrep "$XCODEBUILD_FILTER" \
+    | egrep -v "$XCODEBUILD_FILTER" \
+    | egrep -v '^$' \
     | egrep -v "(GPBDictionary|GPBArray)" -
 
 echo "TIME:  $(date)"
@@ -65,7 +67,10 @@ xcodebuild \
     -workspace Tests.xcworkspace \
     -scheme CronetUnitTests \
     -destination name="iPhone 6" \
-    test | xcpretty
+    test \
+    | egrep -v "$XCODEBUILD_FILTER" \
+    | egrep -v '^$' \
+    | egrep -v "(GPBDictionary|GPBArray)" -
 
 echo "TIME:  $(date)"
 xcodebuild \
@@ -74,5 +79,6 @@ xcodebuild \
     -destination name="iPhone 6" \
     HOST_PORT_REMOTE=grpc-test.sandbox.googleapis.com \
     test \
-    | egrep "$XCODEBUILD_FILTER" \
+    | egrep -v "$XCODEBUILD_FILTER" \
+    | egrep -v '^$' \
     | egrep -v "(GPBDictionary|GPBArray)" -
diff --git a/src/python/grpcio_tests/commands.py b/src/python/grpcio_tests/commands.py
index 162200112a..93f84572b7 100644
--- a/src/python/grpcio_tests/commands.py
+++ b/src/python/grpcio_tests/commands.py
@@ -67,55 +67,6 @@ class GatherProto(setuptools.Command):
             open(path, 'a').close()
 
 
-class BuildProtoModules(setuptools.Command):
-    """Command to generate project *_pb2.py modules from proto files."""
-
-    description = 'build protobuf modules'
-    user_options = [
-        ('include=', None, 'path patterns to include in protobuf generation'),
-        ('exclude=', None, 'path patterns to exclude from protobuf generation')
-    ]
-
-    def initialize_options(self):
-        self.exclude = None
-        self.include = r'.*\.proto$'
-
-    def finalize_options(self):
-        pass
-
-    def run(self):
-        import grpc_tools.protoc as protoc
-
-        include_regex = re.compile(self.include)
-        exclude_regex = re.compile(self.exclude) if self.exclude else None
-        paths = []
-        for walk_root, directories, filenames in os.walk(PROTO_STEM):
-            for filename in filenames:
-                path = os.path.join(walk_root, filename)
-                if include_regex.match(path) and not (
-                        exclude_regex and exclude_regex.match(path)):
-                    paths.append(path)
-
-        # TODO(kpayson): It would be nice to do this in a batch command,
-        # but we currently have name conflicts in src/proto
-        for path in paths:
-            command = [
-                'grpc_tools.protoc',
-                '-I {}'.format(PROTO_STEM),
-                '--python_out={}'.format(PROTO_STEM),
-                '--grpc_python_out={}'.format(PROTO_STEM),
-            ] + [path]
-            if protoc.main(command) != 0:
-                sys.stderr.write(
-                    'warning: Command:\n{}\nFailed'.format(command))
-
-        # Generated proto directories dont include __init__.py, but
-        # these are needed for python package resolution
-        for walk_root, _, _ in os.walk(PROTO_STEM):
-            path = os.path.join(walk_root, '__init__.py')
-            open(path, 'a').close()
-
-
 class BuildPy(build_py.build_py):
     """Custom project build command."""
 
diff --git a/src/python/grpcio_tests/tests/protoc_plugin/protos/invocation_testing/split_messages/__init__.py b/src/python/grpcio_tests/tests/_sanity/__init__.py
index 5772620b60..5772620b60 100644
--- a/src/python/grpcio_tests/tests/protoc_plugin/protos/invocation_testing/split_messages/__init__.py
+++ b/src/python/grpcio_tests/tests/_sanity/__init__.py
diff --git a/src/python/grpcio_tests/tests/unit/_sanity/_sanity_test.py b/src/python/grpcio_tests/tests/_sanity/_sanity_test.py
index 19bc8801eb..b4079850ff 100644
--- a/src/python/grpcio_tests/tests/unit/_sanity/_sanity_test.py
+++ b/src/python/grpcio_tests/tests/_sanity/_sanity_test.py
@@ -21,24 +21,25 @@ import six
 import tests
 
 
-class Sanity(unittest.TestCase):
+class SanityTest(unittest.TestCase):
+
+    maxDiff = 32768
 
     def testTestsJsonUpToDate(self):
         """Autodiscovers all test suites and checks that tests.json is up to date"""
         loader = tests.Loader()
         loader.loadTestsFromNames(['tests'])
-        test_suite_names = [
+        test_suite_names = sorted({
             test_case_class.id().rsplit('.', 1)[0]
             for test_case_class in tests._loader.iterate_suite_cases(
                 loader.suite)
-        ]
-        test_suite_names = sorted(set(test_suite_names))
+        })
 
         tests_json_string = pkg_resources.resource_string('tests', 'tests.json')
-        if six.PY3:
-            tests_json_string = tests_json_string.decode()
-        tests_json = json.loads(tests_json_string)
-        self.assertListEqual(test_suite_names, tests_json)
+        tests_json = json.loads(tests_json_string.decode()
+                                if six.PY3 else tests_json_string)
+
+        self.assertSequenceEqual(tests_json, test_suite_names)
 
 
 if __name__ == '__main__':
diff --git a/src/python/grpcio_tests/tests/protoc_plugin/_python_plugin_test.py b/src/python/grpcio_tests/tests/protoc_plugin/_python_plugin_test.py
index 71493bfec6..5b84001aab 100644
--- a/src/python/grpcio_tests/tests/protoc_plugin/_python_plugin_test.py
+++ b/src/python/grpcio_tests/tests/protoc_plugin/_python_plugin_test.py
@@ -33,7 +33,7 @@ from tests.unit.framework.common import test_constants
 import tests.protoc_plugin.protos.payload.test_payload_pb2 as payload_pb2
 import tests.protoc_plugin.protos.requests.r.test_requests_pb2 as request_pb2
 import tests.protoc_plugin.protos.responses.test_responses_pb2 as response_pb2
-import tests.protoc_plugin.protos.service.test_service_pb2 as service_pb2
+import tests.protoc_plugin.protos.service.test_service_pb2_grpc as service_pb2_grpc
 
 # Identifiers of entities we expect to find in the generated module.
 STUB_IDENTIFIER = 'TestServiceStub'
@@ -138,7 +138,7 @@ def _CreateService():
   """
     servicer_methods = _ServicerMethods()
 
-    class Servicer(getattr(service_pb2, SERVICER_IDENTIFIER)):
+    class Servicer(getattr(service_pb2_grpc, SERVICER_IDENTIFIER)):
 
         def UnaryCall(self, request, context):
             return servicer_methods.UnaryCall(request, context)
@@ -157,11 +157,12 @@ def _CreateService():
 
     server = grpc.server(
         futures.ThreadPoolExecutor(max_workers=test_constants.POOL_SIZE))
-    getattr(service_pb2, ADD_SERVICER_TO_SERVER_IDENTIFIER)(Servicer(), server)
+    getattr(service_pb2_grpc, ADD_SERVICER_TO_SERVER_IDENTIFIER)(Servicer(),
+                                                                 server)
     port = server.add_insecure_port('[::]:0')
     server.start()
     channel = grpc.insecure_channel('localhost:{}'.format(port))
-    stub = getattr(service_pb2, STUB_IDENTIFIER)(channel)
+    stub = getattr(service_pb2_grpc, STUB_IDENTIFIER)(channel)
     return _Service(servicer_methods, server, stub)
 
 
@@ -173,16 +174,17 @@ def _CreateIncompleteService():
       servicer_methods implements none of the methods required of it.
   """
 
-    class Servicer(getattr(service_pb2, SERVICER_IDENTIFIER)):
+    class Servicer(getattr(service_pb2_grpc, SERVICER_IDENTIFIER)):
         pass
 
     server = grpc.server(
         futures.ThreadPoolExecutor(max_workers=test_constants.POOL_SIZE))
-    getattr(service_pb2, ADD_SERVICER_TO_SERVER_IDENTIFIER)(Servicer(), server)
+    getattr(service_pb2_grpc, ADD_SERVICER_TO_SERVER_IDENTIFIER)(Servicer(),
+                                                                 server)
     port = server.add_insecure_port('[::]:0')
     server.start()
     channel = grpc.insecure_channel('localhost:{}'.format(port))
-    stub = getattr(service_pb2, STUB_IDENTIFIER)(channel)
+    stub = getattr(service_pb2_grpc, STUB_IDENTIFIER)(channel)
     return _Service(None, server, stub)
 
 
@@ -223,10 +225,11 @@ class PythonPluginTest(unittest.TestCase):
 
     def testImportAttributes(self):
         # check that we can access the generated module and its members.
-        self.assertIsNotNone(getattr(service_pb2, STUB_IDENTIFIER, None))
-        self.assertIsNotNone(getattr(service_pb2, SERVICER_IDENTIFIER, None))
+        self.assertIsNotNone(getattr(service_pb2_grpc, STUB_IDENTIFIER, None))
         self.assertIsNotNone(
-            getattr(service_pb2, ADD_SERVICER_TO_SERVER_IDENTIFIER, None))
+            getattr(service_pb2_grpc, SERVICER_IDENTIFIER, None))
+        self.assertIsNotNone(
+            getattr(service_pb2_grpc, ADD_SERVICER_TO_SERVER_IDENTIFIER, None))
 
     def testUpDown(self):
         service = _CreateService()
diff --git a/src/python/grpcio_tests/tests/protoc_plugin/_split_definitions_test.py b/src/python/grpcio_tests/tests/protoc_plugin/_split_definitions_test.py
index 1aeb62a7c5..7868cdbfb3 100644
--- a/src/python/grpcio_tests/tests/protoc_plugin/_split_definitions_test.py
+++ b/src/python/grpcio_tests/tests/protoc_plugin/_split_definitions_test.py
@@ -12,22 +12,20 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import collections
+import abc
 from concurrent import futures
 import contextlib
-import distutils.spawn
-import errno
 import importlib
 import os
-import os.path
+from os import path
 import pkgutil
+import platform
 import shutil
-import subprocess
 import sys
 import tempfile
-import threading
 import unittest
-import platform
+
+import six
 
 import grpc
 from grpc_tools import protoc
@@ -37,292 +35,285 @@ _MESSAGES_IMPORT = b'import "messages.proto";'
 _SPLIT_NAMESPACE = b'package grpc_protoc_plugin.invocation_testing.split;'
 _COMMON_NAMESPACE = b'package grpc_protoc_plugin.invocation_testing;'
 
+_RELATIVE_PROTO_PATH = 'relative_proto_path'
+_RELATIVE_PYTHON_OUT = 'relative_python_out'
+
 
 @contextlib.contextmanager
-def _system_path(path):
+def _system_path(path_insertion):
     old_system_path = sys.path[:]
-    sys.path = sys.path[0:1] + path + sys.path[1:]
+    sys.path = sys.path[0:1] + path_insertion + sys.path[1:]
     yield
     sys.path = old_system_path
 
 
-class DummySplitServicer(object):
+# NOTE(nathaniel): https://twitter.com/exoplaneteer/status/677259364256747520
+# Life lesson "just always default to idempotence" reinforced.
+def _create_directory_tree(root, path_components_sequence):
+    created = set()
+    for path_components in path_components_sequence:
+        thus_far = ''
+        for path_component in path_components:
+            relative_path = path.join(thus_far, path_component)
+            if relative_path not in created:
+                os.makedirs(path.join(root, relative_path))
+                created.add(relative_path)
+            thus_far = path.join(thus_far, path_component)
+
+
+def _massage_proto_content(proto_content, test_name_bytes,
+                           messages_proto_relative_file_name_bytes):
+    package_substitution = (b'package grpc_protoc_plugin.invocation_testing.' +
+                            test_name_bytes + b';')
+    common_namespace_substituted = proto_content.replace(_COMMON_NAMESPACE,
+                                                         package_substitution)
+    split_namespace_substituted = common_namespace_substituted.replace(
+        _SPLIT_NAMESPACE, package_substitution)
+    message_import_replaced = split_namespace_substituted.replace(
+        _MESSAGES_IMPORT,
+        b'import "' + messages_proto_relative_file_name_bytes + b'";')
+    return message_import_replaced
+
+
+def _packagify(directory):
+    for subdirectory, _, _ in os.walk(directory):
+        init_file_name = path.join(subdirectory, '__init__.py')
+        with open(init_file_name, 'wb') as init_file:
+            init_file.write(b'')
 
-    def __init__(self, request_class, response_class):
-        self.request_class = request_class
-        self.response_class = response_class
+
+class _Servicer(object):
+
+    def __init__(self, response_class):
+        self._response_class = response_class
 
     def Call(self, request, context):
-        return self.response_class()
+        return self._response_class()
 
 
-class SeparateTestMixin(object):
+def _protoc(proto_path, python_out, grpc_python_out_flag, grpc_python_out,
+            absolute_proto_file_names):
+    args = [
+        '',
+        '--proto_path={}'.format(proto_path),
+    ]
+    if python_out is not None:
+        args.append('--python_out={}'.format(python_out))
+    if grpc_python_out is not None:
+        args.append('--grpc_python_out={}:{}'.format(grpc_python_out_flag,
+                                                     grpc_python_out))
+    args.extend(absolute_proto_file_names)
+    return protoc.main(args)
 
-    def testImportAttributes(self):
-        with _system_path([self.python_out_directory]):
-            pb2 = importlib.import_module(self.pb2_import)
-        pb2.Request
-        pb2.Response
-        if self.should_find_services_in_pb2:
-            pb2.TestServiceServicer
-        else:
-            with self.assertRaises(AttributeError):
-                pb2.TestServiceServicer
-
-        with _system_path([self.grpc_python_out_directory]):
-            pb2_grpc = importlib.import_module(self.pb2_grpc_import)
-        pb2_grpc.TestServiceServicer
-        with self.assertRaises(AttributeError):
-            pb2_grpc.Request
-        with self.assertRaises(AttributeError):
-            pb2_grpc.Response
-
-    def testCall(self):
-        with _system_path([self.python_out_directory]):
-            pb2 = importlib.import_module(self.pb2_import)
-        with _system_path([self.grpc_python_out_directory]):
-            pb2_grpc = importlib.import_module(self.pb2_grpc_import)
-        server = grpc.server(
-            futures.ThreadPoolExecutor(max_workers=test_constants.POOL_SIZE))
-        pb2_grpc.add_TestServiceServicer_to_server(
-            DummySplitServicer(pb2.Request, pb2.Response), server)
-        port = server.add_insecure_port('[::]:0')
-        server.start()
-        channel = grpc.insecure_channel('localhost:{}'.format(port))
-        stub = pb2_grpc.TestServiceStub(channel)
-        request = pb2.Request()
-        expected_response = pb2.Response()
-        response = stub.Call(request)
-        self.assertEqual(expected_response, response)
-
-
-class CommonTestMixin(object):
-
-    def testImportAttributes(self):
-        with _system_path([self.python_out_directory]):
-            pb2 = importlib.import_module(self.pb2_import)
-        pb2.Request
-        pb2.Response
-        if self.should_find_services_in_pb2:
-            pb2.TestServiceServicer
-        else:
-            with self.assertRaises(AttributeError):
-                pb2.TestServiceServicer
-
-        with _system_path([self.grpc_python_out_directory]):
-            pb2_grpc = importlib.import_module(self.pb2_grpc_import)
-        pb2_grpc.TestServiceServicer
-        with self.assertRaises(AttributeError):
-            pb2_grpc.Request
-        with self.assertRaises(AttributeError):
-            pb2_grpc.Response
-
-    def testCall(self):
-        with _system_path([self.python_out_directory]):
-            pb2 = importlib.import_module(self.pb2_import)
-        with _system_path([self.grpc_python_out_directory]):
-            pb2_grpc = importlib.import_module(self.pb2_grpc_import)
-        server = grpc.server(
-            futures.ThreadPoolExecutor(max_workers=test_constants.POOL_SIZE))
-        pb2_grpc.add_TestServiceServicer_to_server(
-            DummySplitServicer(pb2.Request, pb2.Response), server)
-        port = server.add_insecure_port('[::]:0')
-        server.start()
-        channel = grpc.insecure_channel('localhost:{}'.format(port))
-        stub = pb2_grpc.TestServiceStub(channel)
-        request = pb2.Request()
-        expected_response = pb2.Response()
-        response = stub.Call(request)
-        self.assertEqual(expected_response, response)
-
-
-@unittest.skipIf(platform.python_implementation() == "PyPy",
-                 "Skip test if run with PyPy")
-class SameSeparateTest(unittest.TestCase, SeparateTestMixin):
 
-    def setUp(self):
-        same_proto_contents = pkgutil.get_data(
-            'tests.protoc_plugin.protos.invocation_testing', 'same.proto')
-        self.directory = tempfile.mkdtemp(suffix='same_separate', dir='.')
-        self.proto_directory = os.path.join(self.directory, 'proto_path')
-        self.python_out_directory = os.path.join(self.directory, 'python_out')
-        self.grpc_python_out_directory = os.path.join(self.directory,
-                                                      'grpc_python_out')
-        os.makedirs(self.proto_directory)
-        os.makedirs(self.python_out_directory)
-        os.makedirs(self.grpc_python_out_directory)
-        same_proto_file = os.path.join(self.proto_directory,
-                                       'same_separate.proto')
-        open(same_proto_file, 'wb').write(
-            same_proto_contents.replace(
-                _COMMON_NAMESPACE,
-                b'package grpc_protoc_plugin.invocation_testing.same_separate;'))
-        protoc_result = protoc.main([
-            '',
-            '--proto_path={}'.format(self.proto_directory),
-            '--python_out={}'.format(self.python_out_directory),
-            '--grpc_python_out=grpc_2_0:{}'.format(
-                self.grpc_python_out_directory),
-            same_proto_file,
-        ])
-        if protoc_result != 0:
-            raise Exception("unexpected protoc error")
-        open(os.path.join(self.grpc_python_out_directory, '__init__.py'),
-             'w').write('')
-        open(os.path.join(self.python_out_directory, '__init__.py'),
-             'w').write('')
-        self.pb2_import = 'same_separate_pb2'
-        self.pb2_grpc_import = 'same_separate_pb2_grpc'
-        self.should_find_services_in_pb2 = False
+class _Mid2016ProtocStyle(object):
 
-    def tearDown(self):
-        shutil.rmtree(self.directory)
+    def name(self):
+        return 'Mid2016ProtocStyle'
 
+    def grpc_in_pb2_expected(self):
+        return True
 
-@unittest.skipIf(platform.python_implementation() == "PyPy",
-                 "Skip test if run with PyPy")
-class SameCommonTest(unittest.TestCase, CommonTestMixin):
+    def protoc(self, proto_path, python_out, absolute_proto_file_names):
+        return (_protoc(proto_path, python_out, 'grpc_1_0', python_out,
+                        absolute_proto_file_names),)
 
-    def setUp(self):
-        same_proto_contents = pkgutil.get_data(
-            'tests.protoc_plugin.protos.invocation_testing', 'same.proto')
-        self.directory = tempfile.mkdtemp(suffix='same_common', dir='.')
-        self.proto_directory = os.path.join(self.directory, 'proto_path')
-        self.python_out_directory = os.path.join(self.directory, 'python_out')
-        self.grpc_python_out_directory = self.python_out_directory
-        os.makedirs(self.proto_directory)
-        os.makedirs(self.python_out_directory)
-        same_proto_file = os.path.join(self.proto_directory,
-                                       'same_common.proto')
-        open(same_proto_file, 'wb').write(
-            same_proto_contents.replace(
-                _COMMON_NAMESPACE,
-                b'package grpc_protoc_plugin.invocation_testing.same_common;'))
-
-        protoc_result = protoc.main([
-            '',
-            '--proto_path={}'.format(self.proto_directory),
-            '--python_out={}'.format(self.python_out_directory),
-            '--grpc_python_out={}'.format(self.grpc_python_out_directory),
-            same_proto_file,
-        ])
-        if protoc_result != 0:
-            raise Exception("unexpected protoc error")
-        open(os.path.join(self.python_out_directory, '__init__.py'),
-             'w').write('')
-        self.pb2_import = 'same_common_pb2'
-        self.pb2_grpc_import = 'same_common_pb2_grpc'
-        self.should_find_services_in_pb2 = True
 
-    def tearDown(self):
-        shutil.rmtree(self.directory)
+class _SingleProtocExecutionProtocStyle(object):
 
+    def name(self):
+        return 'SingleProtocExecutionProtocStyle'
 
-@unittest.skipIf(platform.python_implementation() == "PyPy",
-                 "Skip test if run with PyPy")
-class SplitCommonTest(unittest.TestCase, CommonTestMixin):
+    def grpc_in_pb2_expected(self):
+        return False
 
-    def setUp(self):
-        services_proto_contents = pkgutil.get_data(
-            'tests.protoc_plugin.protos.invocation_testing.split_services',
-            'services.proto')
-        messages_proto_contents = pkgutil.get_data(
-            'tests.protoc_plugin.protos.invocation_testing.split_messages',
-            'messages.proto')
-        self.directory = tempfile.mkdtemp(suffix='split_common', dir='.')
-        self.proto_directory = os.path.join(self.directory, 'proto_path')
-        self.python_out_directory = os.path.join(self.directory, 'python_out')
-        self.grpc_python_out_directory = self.python_out_directory
-        os.makedirs(self.proto_directory)
-        os.makedirs(self.python_out_directory)
-        services_proto_file = os.path.join(self.proto_directory,
-                                           'split_common_services.proto')
-        messages_proto_file = os.path.join(self.proto_directory,
-                                           'split_common_messages.proto')
-        open(services_proto_file, 'wb').write(
-            services_proto_contents.replace(
-                _MESSAGES_IMPORT, b'import "split_common_messages.proto";')
-            .replace(
-                _SPLIT_NAMESPACE,
-                b'package grpc_protoc_plugin.invocation_testing.split_common;'))
-        open(messages_proto_file, 'wb').write(
-            messages_proto_contents.replace(
-                _SPLIT_NAMESPACE,
-                b'package grpc_protoc_plugin.invocation_testing.split_common;'))
-        protoc_result = protoc.main([
-            '',
-            '--proto_path={}'.format(self.proto_directory),
-            '--python_out={}'.format(self.python_out_directory),
-            '--grpc_python_out={}'.format(self.grpc_python_out_directory),
-            services_proto_file,
-            messages_proto_file,
-        ])
-        if protoc_result != 0:
-            raise Exception("unexpected protoc error")
-        open(os.path.join(self.python_out_directory, '__init__.py'),
-             'w').write('')
-        self.pb2_import = 'split_common_messages_pb2'
-        self.pb2_grpc_import = 'split_common_services_pb2_grpc'
-        self.should_find_services_in_pb2 = False
+    def protoc(self, proto_path, python_out, absolute_proto_file_names):
+        return (_protoc(proto_path, python_out, 'grpc_2_0', python_out,
+                        absolute_proto_file_names),)
+
+
+class _ProtoBeforeGrpcProtocStyle(object):
+
+    def name(self):
+        return 'ProtoBeforeGrpcProtocStyle'
+
+    def grpc_in_pb2_expected(self):
+        return False
+
+    def protoc(self, proto_path, python_out, absolute_proto_file_names):
+        pb2_protoc_exit_code = _protoc(proto_path, python_out, None, None,
+                                       absolute_proto_file_names)
+        pb2_grpc_protoc_exit_code = _protoc(
+            proto_path, None, 'grpc_2_0', python_out, absolute_proto_file_names)
+        return pb2_protoc_exit_code, pb2_grpc_protoc_exit_code,
 
-    def tearDown(self):
-        shutil.rmtree(self.directory)
 
+class _GrpcBeforeProtoProtocStyle(object):
 
-@unittest.skipIf(platform.python_implementation() == "PyPy",
-                 "Skip test if run with PyPy")
-class SplitSeparateTest(unittest.TestCase, SeparateTestMixin):
+    def name(self):
+        return 'GrpcBeforeProtoProtocStyle'
+
+    def grpc_in_pb2_expected(self):
+        return False
+
+    def protoc(self, proto_path, python_out, absolute_proto_file_names):
+        pb2_grpc_protoc_exit_code = _protoc(
+            proto_path, None, 'grpc_2_0', python_out, absolute_proto_file_names)
+        pb2_protoc_exit_code = _protoc(proto_path, python_out, None, None,
+                                       absolute_proto_file_names)
+        return pb2_grpc_protoc_exit_code, pb2_protoc_exit_code,
+
+
+_PROTOC_STYLES = (_Mid2016ProtocStyle(), _SingleProtocExecutionProtocStyle(),
+                  _ProtoBeforeGrpcProtocStyle(), _GrpcBeforeProtoProtocStyle(),)
+
+
+@unittest.skipIf(platform.python_implementation() == 'PyPy',
+                 'Skip test if run with PyPy!')
+class _Test(six.with_metaclass(abc.ABCMeta, unittest.TestCase)):
 
     def setUp(self):
-        services_proto_contents = pkgutil.get_data(
-            'tests.protoc_plugin.protos.invocation_testing.split_services',
-            'services.proto')
-        messages_proto_contents = pkgutil.get_data(
-            'tests.protoc_plugin.protos.invocation_testing.split_messages',
-            'messages.proto')
-        self.directory = tempfile.mkdtemp(suffix='split_separate', dir='.')
-        self.proto_directory = os.path.join(self.directory, 'proto_path')
-        self.python_out_directory = os.path.join(self.directory, 'python_out')
-        self.grpc_python_out_directory = os.path.join(self.directory,
-                                                      'grpc_python_out')
-        os.makedirs(self.proto_directory)
-        os.makedirs(self.python_out_directory)
-        os.makedirs(self.grpc_python_out_directory)
-        services_proto_file = os.path.join(self.proto_directory,
-                                           'split_separate_services.proto')
-        messages_proto_file = os.path.join(self.proto_directory,
-                                           'split_separate_messages.proto')
-        open(services_proto_file, 'wb').write(
-            services_proto_contents.replace(
-                _MESSAGES_IMPORT, b'import "split_separate_messages.proto";')
-            .replace(
-                _SPLIT_NAMESPACE,
-                b'package grpc_protoc_plugin.invocation_testing.split_separate;'
-            ))
-        open(messages_proto_file, 'wb').write(
-            messages_proto_contents.replace(
-                _SPLIT_NAMESPACE,
-                b'package grpc_protoc_plugin.invocation_testing.split_separate;'
-            ))
-        protoc_result = protoc.main([
-            '',
-            '--proto_path={}'.format(self.proto_directory),
-            '--python_out={}'.format(self.python_out_directory),
-            '--grpc_python_out=grpc_2_0:{}'.format(
-                self.grpc_python_out_directory),
-            services_proto_file,
-            messages_proto_file,
-        ])
-        if protoc_result != 0:
-            raise Exception("unexpected protoc error")
-        open(os.path.join(self.python_out_directory, '__init__.py'),
-             'w').write('')
-        self.pb2_import = 'split_separate_messages_pb2'
-        self.pb2_grpc_import = 'split_separate_services_pb2_grpc'
-        self.should_find_services_in_pb2 = False
+        self._directory = tempfile.mkdtemp(suffix=self.NAME, dir='.')
+        self._proto_path = path.join(self._directory, _RELATIVE_PROTO_PATH)
+        self._python_out = path.join(self._directory, _RELATIVE_PYTHON_OUT)
+
+        os.makedirs(self._proto_path)
+        os.makedirs(self._python_out)
+
+        proto_directories_and_names = {
+            (self.MESSAGES_PROTO_RELATIVE_DIRECTORY_NAMES,
+             self.MESSAGES_PROTO_FILE_NAME,),
+            (self.SERVICES_PROTO_RELATIVE_DIRECTORY_NAMES,
+             self.SERVICES_PROTO_FILE_NAME,),
+        }
+        messages_proto_relative_file_name_forward_slashes = '/'.join(
+            self.MESSAGES_PROTO_RELATIVE_DIRECTORY_NAMES + (
+                self.MESSAGES_PROTO_FILE_NAME,))
+        _create_directory_tree(self._proto_path, (
+            relative_proto_directory_names
+            for relative_proto_directory_names, _ in proto_directories_and_names
+        ))
+        self._absolute_proto_file_names = set()
+        for relative_directory_names, file_name in proto_directories_and_names:
+            absolute_proto_file_name = path.join(
+                self._proto_path, *relative_directory_names + (file_name,))
+            raw_proto_content = pkgutil.get_data(
+                'tests.protoc_plugin.protos.invocation_testing',
+                path.join(*relative_directory_names + (file_name,)))
+            massaged_proto_content = _massage_proto_content(
+                raw_proto_content,
+                self.NAME.encode(),
+                messages_proto_relative_file_name_forward_slashes.encode())
+            with open(absolute_proto_file_name, 'wb') as proto_file:
+                proto_file.write(massaged_proto_content)
+            self._absolute_proto_file_names.add(absolute_proto_file_name)
 
     def tearDown(self):
-        shutil.rmtree(self.directory)
+        shutil.rmtree(self._directory)
+
+    def _protoc(self):
+        protoc_exit_codes = self.PROTOC_STYLE.protoc(
+            self._proto_path, self._python_out, self._absolute_proto_file_names)
+        for protoc_exit_code in protoc_exit_codes:
+            self.assertEqual(0, protoc_exit_code)
+
+        _packagify(self._python_out)
+
+        generated_modules = {}
+        expected_generated_full_module_names = {
+            self.EXPECTED_MESSAGES_PB2,
+            self.EXPECTED_SERVICES_PB2,
+            self.EXPECTED_SERVICES_PB2_GRPC,
+        }
+        with _system_path([self._python_out]):
+            for full_module_name in expected_generated_full_module_names:
+                module = importlib.import_module(full_module_name)
+                generated_modules[full_module_name] = module
+
+        self._messages_pb2 = generated_modules[self.EXPECTED_MESSAGES_PB2]
+        self._services_pb2 = generated_modules[self.EXPECTED_SERVICES_PB2]
+        self._services_pb2_grpc = generated_modules[
+            self.EXPECTED_SERVICES_PB2_GRPC]
+
+    def _services_modules(self):
+        if self.PROTOC_STYLE.grpc_in_pb2_expected():
+            return self._services_pb2, self._services_pb2_grpc,
+        else:
+            return self._services_pb2_grpc,
+
+    def test_imported_attributes(self):
+        self._protoc()
+
+        self._messages_pb2.Request
+        self._messages_pb2.Response
+        self._services_pb2.DESCRIPTOR.services_by_name['TestService']
+        for services_module in self._services_modules():
+            services_module.TestServiceStub
+            services_module.TestServiceServicer
+            services_module.add_TestServiceServicer_to_server
+
+    def test_call(self):
+        self._protoc()
+
+        for services_module in self._services_modules():
+            server = grpc.server(
+                futures.ThreadPoolExecutor(
+                    max_workers=test_constants.POOL_SIZE))
+            services_module.add_TestServiceServicer_to_server(
+                _Servicer(self._messages_pb2.Response), server)
+            port = server.add_insecure_port('[::]:0')
+            server.start()
+            channel = grpc.insecure_channel('localhost:{}'.format(port))
+            stub = services_module.TestServiceStub(channel)
+            response = stub.Call(self._messages_pb2.Request())
+            self.assertEqual(self._messages_pb2.Response(), response)
+
+
+def _create_test_case_class(split_proto, protoc_style):
+    attributes = {}
+
+    name = '{}{}'.format('SplitProto' if split_proto else 'SameProto',
+                         protoc_style.name())
+    attributes['NAME'] = name
+
+    if split_proto:
+        attributes['MESSAGES_PROTO_RELATIVE_DIRECTORY_NAMES'] = (
+            'split_messages', 'sub',)
+        attributes['MESSAGES_PROTO_FILE_NAME'] = 'messages.proto'
+        attributes['SERVICES_PROTO_RELATIVE_DIRECTORY_NAMES'] = (
+            'split_services',)
+        attributes['SERVICES_PROTO_FILE_NAME'] = 'services.proto'
+        attributes['EXPECTED_MESSAGES_PB2'] = 'split_messages.sub.messages_pb2'
+        attributes['EXPECTED_SERVICES_PB2'] = 'split_services.services_pb2'
+        attributes['EXPECTED_SERVICES_PB2_GRPC'] = (
+            'split_services.services_pb2_grpc')
+    else:
+        attributes['MESSAGES_PROTO_RELATIVE_DIRECTORY_NAMES'] = ()
+        attributes['MESSAGES_PROTO_FILE_NAME'] = 'same.proto'
+        attributes['SERVICES_PROTO_RELATIVE_DIRECTORY_NAMES'] = ()
+        attributes['SERVICES_PROTO_FILE_NAME'] = 'same.proto'
+        attributes['EXPECTED_MESSAGES_PB2'] = 'same_pb2'
+        attributes['EXPECTED_SERVICES_PB2'] = 'same_pb2'
+        attributes['EXPECTED_SERVICES_PB2_GRPC'] = 'same_pb2_grpc'
+
+    attributes['PROTOC_STYLE'] = protoc_style
+
+    attributes['__module__'] = _Test.__module__
+
+    return type('{}Test'.format(name), (_Test,), attributes)
+
+
+def _create_test_case_classes():
+    for split_proto in (False, True,):
+        for protoc_style in _PROTOC_STYLES:
+            yield _create_test_case_class(split_proto, protoc_style)
+
+
+def load_tests(loader, tests, pattern):
+    tests = tuple(
+        loader.loadTestsFromTestCase(test_case_class)
+        for test_case_class in _create_test_case_classes())
+    return unittest.TestSuite(tests=tests)
 
 
 if __name__ == '__main__':
diff --git a/src/python/grpcio_tests/tests/protoc_plugin/protos/invocation_testing/split_messages/messages.proto b/src/python/grpcio_tests/tests/protoc_plugin/protos/invocation_testing/split_messages/sub/messages.proto
index 1b780c69ba..1b780c69ba 100644
--- a/src/python/grpcio_tests/tests/protoc_plugin/protos/invocation_testing/split_messages/messages.proto
+++ b/src/python/grpcio_tests/tests/protoc_plugin/protos/invocation_testing/split_messages/sub/messages.proto
diff --git a/src/python/grpcio_tests/tests/protoc_plugin/protos/invocation_testing/split_services/__init__.py b/src/python/grpcio_tests/tests/protoc_plugin/protos/invocation_testing/split_services/__init__.py
deleted file mode 100644
index 5772620b60..0000000000
--- a/src/python/grpcio_tests/tests/protoc_plugin/protos/invocation_testing/split_services/__init__.py
+++ /dev/null
@@ -1,13 +0,0 @@
-# Copyright 2016 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.
diff --git a/src/python/grpcio_tests/tests/qps/benchmark_server.py b/src/python/grpcio_tests/tests/qps/benchmark_server.py
index 05101fdc6d..bb07844491 100644
--- a/src/python/grpcio_tests/tests/qps/benchmark_server.py
+++ b/src/python/grpcio_tests/tests/qps/benchmark_server.py
@@ -13,10 +13,10 @@
 # limitations under the License.
 
 from src.proto.grpc.testing import messages_pb2
-from src.proto.grpc.testing import services_pb2
+from src.proto.grpc.testing import services_pb2_grpc
 
 
-class BenchmarkServer(services_pb2.BenchmarkServiceServicer):
+class BenchmarkServer(services_pb2_grpc.BenchmarkServiceServicer):
     """Synchronous Server implementation for the Benchmark service."""
 
     def UnaryCall(self, request, context):
@@ -29,7 +29,7 @@ class BenchmarkServer(services_pb2.BenchmarkServiceServicer):
             yield messages_pb2.SimpleResponse(payload=payload)
 
 
-class GenericBenchmarkServer(services_pb2.BenchmarkServiceServicer):
+class GenericBenchmarkServer(services_pb2_grpc.BenchmarkServiceServicer):
     """Generic Server implementation for the Benchmark service."""
 
     def __init__(self, resp_size):
diff --git a/src/python/grpcio_tests/tests/stress/metrics_server.py b/src/python/grpcio_tests/tests/stress/metrics_server.py
index 11ab6c3f4e..33a74b4a38 100644
--- a/src/python/grpcio_tests/tests/stress/metrics_server.py
+++ b/src/python/grpcio_tests/tests/stress/metrics_server.py
@@ -16,11 +16,12 @@
 import time
 
 from src.proto.grpc.testing import metrics_pb2
+from src.proto.grpc.testing import metrics_pb2_grpc
 
 GAUGE_NAME = 'python_overall_qps'
 
 
-class MetricsServer(metrics_pb2.MetricsServiceServicer):
+class MetricsServer(metrics_pb2_grpc.MetricsServiceServicer):
 
     def __init__(self, histogram):
         self._start_time = time.time()
diff --git a/src/python/grpcio_tests/tests/tests.json b/src/python/grpcio_tests/tests/tests.json
index 4c078e6c22..8512d5b96f 100644
--- a/src/python/grpcio_tests/tests/tests.json
+++ b/src/python/grpcio_tests/tests/tests.json
@@ -1,12 +1,17 @@
 [
+  "_sanity._sanity_test.SanityTest",
   "health_check._health_servicer_test.HealthServicerTest",
   "interop._insecure_intraop_test.InsecureIntraopTest",
   "interop._secure_intraop_test.SecureIntraopTest",
   "protoc_plugin._python_plugin_test.PythonPluginTest",
-  "protoc_plugin._split_definitions_test.SameCommonTest",
-  "protoc_plugin._split_definitions_test.SameSeparateTest",
-  "protoc_plugin._split_definitions_test.SplitCommonTest",
-  "protoc_plugin._split_definitions_test.SplitSeparateTest",
+  "protoc_plugin._split_definitions_test.SameProtoGrpcBeforeProtoProtocStyleTest",
+  "protoc_plugin._split_definitions_test.SameProtoMid2016ProtocStyleTest",
+  "protoc_plugin._split_definitions_test.SameProtoProtoBeforeGrpcProtocStyleTest",
+  "protoc_plugin._split_definitions_test.SameProtoSingleProtocExecutionProtocStyleTest",
+  "protoc_plugin._split_definitions_test.SplitProtoGrpcBeforeProtoProtocStyleTest",
+  "protoc_plugin._split_definitions_test.SplitProtoMid2016ProtocStyleTest",
+  "protoc_plugin._split_definitions_test.SplitProtoProtoBeforeGrpcProtocStyleTest",
+  "protoc_plugin._split_definitions_test.SplitProtoSingleProtocExecutionProtocStyleTest",
   "protoc_plugin.beta_python_plugin_test.PythonPluginTest",
   "reflection._reflection_servicer_test.ReflectionServicerTest",
   "testing._client_test.ClientTest",
@@ -41,7 +46,6 @@
   "unit._reconnect_test.ReconnectTest",
   "unit._resource_exhausted_test.ResourceExhaustedTest",
   "unit._rpc_test.RPCTest",
-  "unit._sanity._sanity_test.Sanity",
   "unit._thread_cleanup_test.CleanupThreadTest",
   "unit.beta._beta_features_test.BetaFeaturesTest",
   "unit.beta._beta_features_test.ContextManagementAndLifecycleTest",
diff --git a/src/python/grpcio_tests/tests/unit/_sanity/__init__.py b/src/python/grpcio_tests/tests/unit/_sanity/__init__.py
deleted file mode 100644
index 5772620b60..0000000000
--- a/src/python/grpcio_tests/tests/unit/_sanity/__init__.py
+++ /dev/null
@@ -1,13 +0,0 @@
-# Copyright 2016 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.
diff --git a/src/ruby/qps/proxy-worker.rb b/src/ruby/qps/proxy-worker.rb
index d7a9f114bd..488610ae74 100755
--- a/src/ruby/qps/proxy-worker.rb
+++ b/src/ruby/qps/proxy-worker.rb
@@ -41,7 +41,7 @@ class ProxyBenchmarkClientServiceImpl < Grpc::Testing::ProxyClientService::Servi
     @histogram = Histogram.new(@histres, @histmax)
     @start_time = Time.now
     # TODO(vjpai): Support multiple client channels by spawning off a PHP client per channel
-    command = "php " + File.expand_path(File.dirname(__FILE__)) + "/../../php/tests/qps/client.php " + @mytarget
+    command = "php -d extension=" + File.expand_path(File.dirname(__FILE__)) + "/../../php/ext/grpc/modules/grpc.so " + File.expand_path(File.dirname(__FILE__)) + "/../../php/tests/qps/client.php " + @mytarget
     puts "Starting command: " + command
     @php_pid = spawn(command)
   end