add fake rpc to send

paddle/fluid/operators/distributed/communicator.cc

@@ -191,6 +191,7 @@ void Communicator::RecvThread() {
 
 void Communicator::Send(const std::string &var_name,
                         const framework::Scope &scope) {
+  if (!FLAGS_communicator_fake_rpc) {
     VLOG(3) << "communicator send " << var_name;
     // push var into send queue by var_name
     auto *grad_var = scope.FindVar(var_name);
@@ -200,6 +201,7 @@ void Communicator::Send(const std::string &var_name,
     auto &queue = send_varname_to_queue_.at(var_name);
     VLOG(3) << "send " << var_name << " queue size " << queue->Size();
     queue->Push(tmp_grad_var);
+  }
 }
 
 Communicator *Communicator::GetInstance() { return communicator_.get(); }