Fix shutdown problems with sync server

src/core/lib/surface/call.c

@@ -1551,6 +1551,10 @@ static grpc_call_error call_start_batch(grpc_exec_ctx *exec_ctx,
           error = GRPC_CALL_ERROR_TOO_MANY_OPERATIONS;
           goto done_with_error;
         }
+        /* IF this is a server, then GRPC_OP_RECV_INITIAL_METADATA *must* come
+           from server.c. In that case, it's coming from accept_stream, and in
+           that case we're not necessarily covered by a poller. */
+        stream_op->covered_by_poller = call->is_client;
         call->received_initial_metadata = 1;
         call->buffered_metadata[0] = op->data.recv_initial_metadata;
         grpc_closure_init(&call->receiving_initial_metadata_ready,

src/cpp/server/server_cc.cc

@@ -510,12 +510,6 @@ void Server::ShutdownInternal(gpr_timespec deadline) {
     ShutdownTag shutdown_tag;  // Dummy shutdown tag
     grpc_server_shutdown_and_notify(server_, shutdown_cq.cq(), &shutdown_tag);
 
-    // Shutdown all ThreadManagers. This will try to gracefully stop all the
-    // threads in the ThreadManagers (once they process any inflight requests)
-    for (auto it = sync_req_mgrs_.begin(); it != sync_req_mgrs_.end(); it++) {
-      (*it)->Shutdown();  // ThreadManager's Shutdown()
-    }
-
     shutdown_cq.Shutdown();
 
     void* tag;
@@ -531,6 +525,12 @@ void Server::ShutdownInternal(gpr_timespec deadline) {
     // Else in case of SHUTDOWN or GOT_EVENT, it means that the server has
     // successfully shutdown
 
+    // Shutdown all ThreadManagers. This will try to gracefully stop all the
+    // threads in the ThreadManagers (once they process any inflight requests)
+    for (auto it = sync_req_mgrs_.begin(); it != sync_req_mgrs_.end(); it++) {
+      (*it)->Shutdown();  // ThreadManager's Shutdown()
+    }
+
     // Wait for threads in all ThreadManagers to terminate
     for (auto it = sync_req_mgrs_.begin(); it != sync_req_mgrs_.end(); it++) {
       (*it)->Wait();