Created by: Yancey1989

After received enough batch barrier, listen_and_serv will execute listen_and_serv once again.

I0209 07:38:45.277182 12426 grpc_server.cc:178] Create RequestSend status:0
I0209 07:38:45.277454 12309 listen_and_serv_op.cc:132] received grad: emb@GRAD.block1 updating param: emb.block1
I0209 07:38:45.277521 12426 grpc_server.cc:231] cq_send status:1
I0209 07:38:45.279542 12309 listen_and_serv_op.cc:118] recv batch barrier message
I0209 07:38:45.279558 12309 listen_and_serv_op.cc:146] recv 120 parmeters for one barrier.
I0209 07:38:45.279664 12309 executor.cc:121] Op(listen_and_serv), inputs:{}, outputs:{}.
I0209 07:38:45.279845 12579 grpc_server.cc:137] Server listening on 127.0.0.1:7164
I0209 07:38:45.279980 12580 grpc_server.cc:178] Create RequestSend status:0
I0209 07:38:45.280047 12581 grpc_server.cc:188] Create RequestGet status:0