Merge pull request #14204 from yashykt/ssltestfix

Fix end2end test flake #13477

test/core/end2end/h2_ssl_cert_test.cc

@@ -272,6 +272,20 @@ static void drain_cq(grpc_completion_queue* cq) {
 
 static void shutdown_server(grpc_end2end_test_fixture* f) {
   if (!f->server) return;
+  /* Perform a completion queue next, so that any pending operations can be
+   * finished, and resources can be released. This is so that, shutdown does not
+   * hang. For example, the server might be stuck in the handshaking code, which
+   * keeps a ref to a listener. Unless, it is unref'd, shutdown won't be able
+   * to proceed.
+   *
+   * (If shutdown times out, it is probably because 100ms wasn't enough. In that
+   * case, the deadline can be increased. Or, we could simply have another
+   * thread for the server to poll the completion queue while the shutdown
+   * progresses.)
+   */
+  GPR_ASSERT(grpc_completion_queue_next(
+                 f->cq, grpc_timeout_milliseconds_to_deadline(100), nullptr)
+                 .type == GRPC_QUEUE_TIMEOUT);
   grpc_server_shutdown_and_notify(f->server, f->shutdown_cq, tag(1000));
   GPR_ASSERT(grpc_completion_queue_pluck(f->shutdown_cq, tag(1000),
                                          grpc_timeout_seconds_to_deadline(5),
@@ -288,8 +302,8 @@ static void shutdown_client(grpc_end2end_test_fixture* f) {
 }
 
 static void end_test(grpc_end2end_test_fixture* f) {
-  shutdown_server(f);
   shutdown_client(f);
+  shutdown_server(f);
 
   grpc_completion_queue_shutdown(f->cq);
   drain_cq(f->cq);