RuntimeError: An attempt has been made to start a new process before the current process（解决方案））

在使用pytorch训练模型时，遇到了这样的错误：

RuntimeError:
        An attempt has been made to start a new process before the
        current process has finished its bootstrapping phase.

        This probably means that you are not using fork to start your
        child processes and you have forgotten to use the proper idiom
        in the main module:

            if __name__ == '__main__':
                freeze_support()
                ...

        The "freeze_support()" line can be omitted if the program
        is not going to be frozen to produce an executable.
    ForkingPickler(file, protocol).dump(obj)
BrokenPipeError: [Errno 32] Broken pipe

报错原因：在linux系统中可以使用多个子进程加载数据，而在windows系统中不能。所以在windows中要将DataLoader中的num_workers设置为0或者采用默认为0的设置
例如下图将num_workers的默认值置0，即可解决此报错问题