Change client context allocation

test/cpp/microbenchmarks/callback_unary_ping_pong.h

@@ -37,26 +37,26 @@ namespace testing {
  */
 
 // Send next rpc when callback function is evoked.
-void SendCallbackUnaryPingPong(benchmark::State* state, EchoRequest* request,
-                               EchoResponse* response,
+void SendCallbackUnaryPingPong(benchmark::State* state, ClientContext* cli_ctx,
+                               EchoRequest* request, EchoResponse* response,
                                EchoTestService::Stub* stub_, bool* done,
                                std::mutex* mu, std::condition_variable* cv) {
   int response_msgs_size = state->range(1);
-  ClientContext* cli_ctx = new ClientContext();
   cli_ctx->AddMetadata(kServerMessageSize, grpc::to_string(response_msgs_size));
   stub_->experimental_async()->Echo(
       cli_ctx, request, response,
       [state, cli_ctx, request, response, stub_, done, mu, cv](Status s) {
         GPR_ASSERT(s.ok());
         if (state->KeepRunning()) {
-          SendCallbackUnaryPingPong(state, request, response, stub_, done, mu,
-                                    cv);
+          cli_ctx->~ClientContext();
+          new (cli_ctx) ClientContext();
+          SendCallbackUnaryPingPong(state, cli_ctx, request, response, stub_,
+                                    done, mu, cv);
         } else {
           std::lock_guard<std::mutex> l(*mu);
           *done = true;
           cv->notify_one();
         }
-        delete cli_ctx;
       });
 };
 
@@ -70,6 +70,7 @@ static void BM_CallbackUnaryPingPong(benchmark::State& state) {
       EchoTestService::NewStub(fixture->channel()));
   EchoRequest request;
   EchoResponse response;
+  ClientContext cli_ctx;
 
   if (request_msgs_size > 0) {
     request.set_message(std::string(request_msgs_size, 'a'));
@@ -82,7 +83,7 @@ static void BM_CallbackUnaryPingPong(benchmark::State& state) {
   bool done = false;
   if (state.KeepRunning()) {
     GPR_TIMER_SCOPE("BenchmarkCycle", 0);
-    SendCallbackUnaryPingPong(&state, &request, &response, stub_.get(), &done,
+    SendCallbackUnaryPingPong(&state, &cli_ctx, &request, &response, stub_.get(), &done,
                               &mu, &cv);
   }
   std::unique_lock<std::mutex> l(mu);