Make sure to poll cq

test/cpp/end2end/server_builder_plugin_test.cc

@@ -37,6 +37,7 @@
 #include <grpc++/impl/server_builder_option.h>
 #include <grpc++/impl/server_builder_plugin.h>
 #include <grpc++/impl/server_initializer.h>
+#include <grpc++/impl/thd.h>
 #include <grpc++/security/credentials.h>
 #include <grpc++/security/server_credentials.h>
 #include <grpc++/server.h>
@@ -188,6 +189,7 @@ class ServerBuilderPluginTest : public ::testing::TestWithParam<bool> {
     grpc::string server_address = "localhost:" + to_string(port_);
     builder_->AddListeningPort(server_address, InsecureServerCredentials());
     cq_ = builder_->AddCompletionQueue();
+    cq_thread_ = grpc::thread(std::bind(&ServerBuilderPluginTest::RunCQ, this));
     server_ = builder_->BuildAndStart();
     EXPECT_TRUE(CheckPresent());
   }
@@ -204,11 +206,8 @@ class ServerBuilderPluginTest : public ::testing::TestWithParam<bool> {
     EXPECT_TRUE(plugin->init_server_is_called());
     EXPECT_TRUE(plugin->finish_is_called());
     server_->Shutdown();
-    void* tag;
-    bool ok;
     cq_->Shutdown();
-    while (cq_->Next(&tag, &ok))
-      ;
+    cq_thread_.join();
   }
 
   string to_string(const int number) {
@@ -223,6 +222,7 @@ class ServerBuilderPluginTest : public ::testing::TestWithParam<bool> {
   std::unique_ptr<grpc::testing::EchoTestService::Stub> stub_;
   std::unique_ptr<ServerCompletionQueue> cq_;
   std::unique_ptr<Server> server_;
+  grpc::thread cq_thread_;
   TestServiceImpl service_;
   int port_;
 
@@ -238,6 +238,13 @@ class ServerBuilderPluginTest : public ::testing::TestWithParam<bool> {
       return nullptr;
     }
   }
+
+  void RunCQ() {
+    void* tag;
+    bool ok;
+    while (cq_->Next(&tag, &ok))
+      ;
+  }
 };
 
 TEST_P(ServerBuilderPluginTest, PluginWithoutServiceTest) {