Created by: XipengY

版本、环境信息： 1）PaddlePaddle版本：1.5.0 2）GPU：GPU：k40， cuda：9.0 cudnn：7.0 4）系统环境：centos6.3，Python2.7

问题描述： data reader部分，如果use_multiprocess = False,能正常train；设置use_multiprocess = True，train报错，错误信息如下： Exception in thread Thread-1: Traceback (most recent call last): File "python2.7/threading.py", line 801, in __bootstrap_inner self.run() File "python2.7/threading.py", line 754, in run self.__target(*self.__args, **self.__kwargs) File "python2.7/site-packages/paddle/fluid/layers/io.py", line 593, in provider_thread raise ex TypeError: 'NoneType' object is not iterable