Question

我在PyTorch网站上的“入门”部分中遵循了本教程：“使用PyTorch进行深度学习：60分钟的闪电战”，并在页面底部下载了"Training a Classifier"的代码，然后运行了该代码，而且对我不起作用。我正在使用PyTorch的CPU版本，如果有区别的话。我是Python的新手，基本上是为Pytorch学习的。这是错误消息，Control + K对我不起作用，因为我认为前几篇文章的编辑界面不同，Stack Overflow需要对其进行修复。或可能只是我的浏览器：

Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "C:\ProgramData\Anaconda3\lib\multiprocessing\spawn.py", line 105, in spawn_main
exitcode = _main(fd)
  File "C:\ProgramData\Anaconda3\lib\multiprocessing\spawn.py", line 114, in _main
prepare(preparation_data)
  File "C:\ProgramData\Anaconda3\lib\multiprocessing\spawn.py", line 225, in prepare
_fixup_main_from_path(data['init_main_from_path'])
  File "C:\ProgramData\Anaconda3\lib\multiprocessing\spawn.py", line 277, in _fixup_main_from_path
run_name="__mp_main__")
  File "C:\ProgramData\Anaconda3\lib\runpy.py", line 263, in run_path
pkg_name=pkg_name, script_name=fname)
  File "C:\ProgramData\Anaconda3\lib\runpy.py", line 96, in _run_module_code
mod_name, mod_spec, pkg_name, script_name)
  File "C:\ProgramData\Anaconda3\lib\runpy.py", line 85, in _run_code
exec(code, run_globals)
  File "C:\Users\Anonymous\PycharmProjects\pytorchHelloWorld\train_network.py", line 100, in <module>
dataiter = iter(trainloader)
  File "C:\ProgramData\Anaconda3\lib\site-packages\torch\utils\data\dataloader.py", line 819, in __iter__
return _DataLoaderIter(self)
  File "C:\ProgramData\Anaconda3\lib\site-packages\torch\utils\data\dataloader.py", line 560, in __init__
w.start()
  File "C:\ProgramData\Anaconda3\lib\multiprocessing\process.py", line 112, in start
self._popen = self._Popen(self)
  File "C:\ProgramData\Anaconda3\lib\multiprocessing\context.py", line 223, in _Popen
return _default_context.get_context().Process._Popen(process_obj)
  File "C:\ProgramData\Anaconda3\lib\multiprocessing\context.py", line 322, in _Popen
return Popen(process_obj)
  File "C:\ProgramData\Anaconda3\lib\multiprocessing\popen_spawn_win32.py", line 33, in __init__
prep_data = spawn.get_preparation_data(process_obj._name)
  File "C:\ProgramData\Anaconda3\lib\multiprocessing\spawn.py", line 143, in get_preparation_data
_check_not_importing_main()
  File "C:\ProgramData\Anaconda3\lib\multiprocessing\spawn.py", line 136, in _check_not_importing_main
is not going to be frozen to produce an executable.''')
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.
Traceback (most recent call last):
 File "C:/Users/Anonymous/PycharmProjects/pytorchHelloWorld/train_network.py", line 100, in <module>
dataiter = iter(trainloader)
  File "C:\ProgramData\Anaconda3\lib\site-packages\torch\utils\data\dataloader.py", line 819, in __iter__
return _DataLoaderIter(self)
  File "C:\ProgramData\Anaconda3\lib\site-packages\torch\utils\data\dataloader.py", line 560, in __init__
w.start()
  File "C:\ProgramData\Anaconda3\lib\multiprocessing\process.py", line 112, in start
self._popen = self._Popen(self)
  File "C:\ProgramData\Anaconda3\lib\multiprocessing\context.py", line 223, in _Popen
return _default_context.get_context().Process._Popen(process_obj)
  File "C:\ProgramData\Anaconda3\lib\multiprocessing\context.py", line 322, in _Popen
return Popen(process_obj)
  File "C:\ProgramData\Anaconda3\lib\multiprocessing\popen_spawn_win32.py", line 65, in __init__
reduction.dump(process_obj, to_child)
  File "C:\ProgramData\Anaconda3\lib\multiprocessing\reduction.py", line 60, in dump
ForkingPickler(file, protocol).dump(obj)
BrokenPipeError: [Errno 32] Broken pipe

Answer 1

由于本教程使用的是DataLoader，因此该错误很可能是由于num_workers=2和Windows中的多重处理所致。 Python3 documentation在此方面分享了一些准则：

确保可以通过新的Python解释器安全地导入主模块，而不会引起意外的副作用（例如，启动新进程）。

您可以设置num_workers=0或将代码包装在if __name__ == '__main__'内

# Safe DataLoader multiprocessing with Windows
if __name__ == '__main__':
    # Code to load the data with num_workers > 1

在PyTorch论坛上查看此reply，了解更多详细信息，在GitHub上查看此issue。

PyTorch入门示例不起作用

1 个答案: