Better fix for flow control bug

src/core/ext/transport/chttp2/transport/internal.h

@@ -630,7 +630,7 @@ int grpc_chttp2_list_pop_check_read_ops(
 void grpc_chttp2_list_add_writing_stalled_by_transport(
     grpc_chttp2_transport_writing *transport_writing,
     grpc_chttp2_stream_writing *stream_writing);
-void grpc_chttp2_list_flush_writing_stalled_by_transport(
+bool grpc_chttp2_list_flush_writing_stalled_by_transport(
     grpc_exec_ctx *exec_ctx, grpc_chttp2_transport_writing *transport_writing);
 
 void grpc_chttp2_list_add_stalled_by_transport(

src/core/ext/transport/chttp2/transport/parsing.c

@@ -87,8 +87,8 @@ void grpc_chttp2_prepare_to_read(
          transport_global->settings[GRPC_SENT_SETTINGS],
          sizeof(transport_parsing->last_sent_settings));
   transport_parsing->max_frame_size =
-      transport_global->settings[GRPC_ACKED_SETTINGS]
+      transport_global
-                                [GRPC_CHTTP2_SETTINGS_MAX_FRAME_SIZE];
+          ->settings[GRPC_ACKED_SETTINGS][GRPC_CHTTP2_SETTINGS_MAX_FRAME_SIZE];
 
   /* update the parsing view of incoming window */
   while (grpc_chttp2_list_pop_unannounced_incoming_window_available(
@@ -154,11 +154,8 @@ void grpc_chttp2_publish_reads(
                                   transport_parsing, outgoing_window);
   is_zero = transport_global->outgoing_window <= 0;
   if (was_zero && !is_zero) {
-    while (grpc_chttp2_list_pop_stalled_by_transport(transport_global,
+    grpc_chttp2_initiate_write(exec_ctx, transport_global, false,
-                                                     &stream_global)) {
+                               "new_global_flow_control");
-      grpc_chttp2_become_writable(exec_ctx, transport_global, stream_global,
-                                  false, "transport.read_flow_control");
-    }
   }
 
   if (transport_parsing->incoming_window <
@@ -169,7 +166,8 @@ void grpc_chttp2_publish_reads(
                                       announce_incoming_window, announce_bytes);
     GRPC_CHTTP2_FLOW_CREDIT_TRANSPORT("parsed", transport_parsing,
                                       incoming_window, announce_bytes);
-    grpc_chttp2_initiate_write(exec_ctx, transport_global, false, "global incoming window");
+    grpc_chttp2_initiate_write(exec_ctx, transport_global, false,
+                               "global incoming window");
   }
 
   /* for each stream that saw an update, fixup global state */

src/core/ext/transport/chttp2/transport/stream_lists.c

@@ -329,6 +329,7 @@ void grpc_chttp2_list_add_writing_stalled_by_transport(
     grpc_chttp2_transport_writing *transport_writing,
     grpc_chttp2_stream_writing *stream_writing) {
   grpc_chttp2_stream *stream = STREAM_FROM_WRITING(stream_writing);
+  gpr_log(GPR_DEBUG, "writing stalled %d", stream->global.id);
   if (!stream->included[GRPC_CHTTP2_LIST_WRITING_STALLED_BY_TRANSPORT]) {
     GRPC_CHTTP2_STREAM_REF(&stream->global, "chttp2_writing_stalled");
   }
@@ -336,22 +337,28 @@ void grpc_chttp2_list_add_writing_stalled_by_transport(
                   GRPC_CHTTP2_LIST_WRITING_STALLED_BY_TRANSPORT);
 }
 
-void grpc_chttp2_list_flush_writing_stalled_by_transport(
+bool grpc_chttp2_list_flush_writing_stalled_by_transport(
     grpc_exec_ctx *exec_ctx, grpc_chttp2_transport_writing *transport_writing) {
   grpc_chttp2_stream *stream;
+  bool out = false;
   grpc_chttp2_transport *transport = TRANSPORT_FROM_WRITING(transport_writing);
   while (stream_list_pop(transport, &stream,
                          GRPC_CHTTP2_LIST_WRITING_STALLED_BY_TRANSPORT)) {
+    gpr_log(GPR_DEBUG, "move %d from writing stalled to just stalled",
+            stream->global.id);
     grpc_chttp2_list_add_stalled_by_transport(transport_writing,
                                               &stream->writing);
     GRPC_CHTTP2_STREAM_UNREF(exec_ctx, &stream->global,
                              "chttp2_writing_stalled");
+    out = true;
   }
+  return out;
 }
 
 void grpc_chttp2_list_add_stalled_by_transport(
     grpc_chttp2_transport_writing *transport_writing,
     grpc_chttp2_stream_writing *stream_writing) {
+  gpr_log(GPR_DEBUG, "stalled %d", stream_writing->id);
   stream_list_add(TRANSPORT_FROM_WRITING(transport_writing),
                   STREAM_FROM_WRITING(stream_writing),
                   GRPC_CHTTP2_LIST_STALLED_BY_TRANSPORT);

src/core/ext/transport/chttp2/transport/writing.c

@@ -75,6 +75,13 @@ int grpc_chttp2_unlocking_check_writes(
 
   GRPC_CHTTP2_FLOW_MOVE_TRANSPORT("write", transport_writing, outgoing_window,
                                   transport_global, outgoing_window);
+  if (transport_writing->outgoing_window > 0) {
+    while (grpc_chttp2_list_pop_stalled_by_transport(transport_global,
+                                                     &stream_global)) {
+      grpc_chttp2_become_writable(exec_ctx, transport_global, stream_global,
+                                  false, "transport.read_flow_control");
+    }
+  }
 
   /* for each grpc_chttp2_stream that's become writable, frame it's data
      (according to available window sizes) and add to the output buffer */
@@ -328,8 +335,11 @@ void grpc_chttp2_cleanup_writing(
   grpc_chttp2_stream_writing *stream_writing;
   grpc_chttp2_stream_global *stream_global;
 
-  grpc_chttp2_list_flush_writing_stalled_by_transport(exec_ctx,
+  if (grpc_chttp2_list_flush_writing_stalled_by_transport(exec_ctx,
-                                                      transport_writing);
+                                                          transport_writing)) {
+    grpc_chttp2_initiate_write(exec_ctx, transport_global, false,
+                               "resume_stalled_stream");
+  }
 
   while (grpc_chttp2_list_pop_written_stream(
       transport_global, transport_writing, &stream_global, &stream_writing)) {

test/cpp/end2end/end2end_test.cc

@@ -1166,6 +1166,9 @@ TEST_P(ProxyEnd2endTest, HugeResponse) {
   request.mutable_param()->set_response_message_length(kResponseSize);
 
   ClientContext context;
+  std::chrono::system_clock::time_point deadline =
+      std::chrono::system_clock::now() + std::chrono::seconds(20);
+  context.set_deadline(deadline);
   Status s = stub_->Echo(&context, request, &response);
   EXPECT_EQ(kResponseSize, response.message().size());
   EXPECT_TRUE(s.ok());