Question

您好我正在尝试在keras中使用fit_generator（Windows 10，最新的keras版本，gtx 1060）但是当我将use_multiprocessing切换为true时，程序会冻结并且会弹出此错误：

Epoch 1/1
Exception in thread Thread-1:
Traceback (most recent call last):
  File "C:\ProgramData\Anaconda3\lib\threading.py", line 916, in _bootstrap_inner
    self.run()
  File "C:\ProgramData\Anaconda3\lib\threading.py", line 864, in run
    self._target(*self._args, **self._kwargs)
  File "C:\ProgramData\Anaconda3\lib\site-packages\keras\utils\data_utils.py", line 548, in _run
    with closing(self.executor_fn(_SHARED_SEQUENCES)) as executor:
  File "C:\ProgramData\Anaconda3\lib\site-packages\keras\utils\data_utils.py", line 522, in <lambda>
    initargs=(seqs,))
  File "C:\ProgramData\Anaconda3\lib\multiprocessing\context.py", line 119, in Pool
    context=self.get_context())
  File "C:\ProgramData\Anaconda3\lib\multiprocessing\pool.py", line 174, in __init__
    self._repopulate_pool()
  File "C:\ProgramData\Anaconda3\lib\multiprocessing\pool.py", line 239, in _repopulate_pool
    w.start()
  File "C:\ProgramData\Anaconda3\lib\multiprocessing\process.py", line 105, in start
    self._popen = self._Popen(self)
  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.

当我在没有多处理的情况下进行训练时，不会发生错误。

Answer 1

这与python multiprocessing on windows, if __name__ == "__main__"

基本上是相同的问题

由于Windows没有fork，因此多处理模块将启动一个新的Python进程并导入调用模块。如果没有__name__ == __main__惯用语，新过程（由keras的fit_generator()开始）将再次调用您的所有代码，并开始另一个过程，等等，等等（直到OOM）。

您必须将初始代码放入main中，并将多处理部分放在外面。

使用keras fit_generator进行多处理的运行时错误

1 个答案: