Created by: jacquesqiao

/Users/qiaolongfei/project/paddle/paddle/fluid/operators/detail/grpc_server.h:75:15: error: private field 'barrier_cond_step_' is not used [-Werror,-Wunused-private-field]
  mutable int barrier_cond_step_;

/Users/qiaolongfei/project/paddle/paddle/fluid/operators/listen_and_serv_op.cc:225:29: error: moving a temporary object prevents copy elision [-Werror,-Wpessimizing-move]
  h->SetPrefetchPreparedCtx(std::move(
                            ^
/Users/qiaolongfei/project/paddle/paddle/fluid/operators/listen_and_serv_op.cc:225:29: note: remove std::move call here
  h->SetPrefetchPreparedCtx(std::move(
                            ^~~~~~~~~~