train因Deadline Exceeded连不上ps会core dump，程序应该平稳退出
Created by: kolinwei
End pass 4, train_loss 2.88446474075, train_acc1 0.378594011068, train_acc5 0.633796095848, test_loss 2.4196540374, test_acc1 0.44827724359, test_acc5 0.70953525641
F0628 11:17:58.649018 220 grpc_client.cc:248] var: name:[batch_norm_22.w_0] ep:[192.168.16.34:5002] grpc error:Deadline Exceeded
* Check failure stack trace: *
@ 0x7f1a1031d07d google::LogMessage::Fail()
@ 0x7f1a10320b2c google::LogMessage::SendToLog()
@ 0x7f1a1031cba3 google::LogMessage::Flush()
@ 0x7f1a1032203e google::LogMessageFatal::~LogMessageFatal()
@ 0x7f1a100d0db0 paddle::operators::distributed::GRPCClient::Proceed()
@ 0x7f1a21fafc80 (unknown)
@ 0x7f1a6312f6ba start_thread
@ 0x7f1a62e6541d clone
@ (nil) (unknown)
Aborted (core dumped)
程序应该平稳退出
