在使用setuptools安装的脚本中使用multiprocessing.Process

Question

我写了一些Python脚本，这些脚本是通过setuptools来部署的。在这些脚本里，我使用了multiprocess.Process，但当我启动部署好的脚本时，它会出现一个错误信息：

Traceback (most recent call last):
  File "C:\Python34\Scripts\process_demo.py", line 4, in <module>
    __import__('pkg_resources').run_script('procdemo==1.0', 'process_demo.py')
  File "C:\Python34\lib\site-packages\setuptools-5.4.1-py3.4.egg\pkg_resources.py", line 534, in run_script
    self.require(requires)[0].run_script(script_name, ns)
  File "C:\Python34\lib\site-packages\setuptools-5.4.1-py3.4.egg\pkg_resources.py", line 1445, in run_script
    "Can't perform this operation for unregistered loader type"
  File "C:\Python34\lib\site-packages\procdemo-1.0-py3.4.egg\EGG-INFO\scripts\process_demo.py", line 19, in <module>
  File "C:\Python34\lib\site-packages\procdemo-1.0-py3.4.egg\EGG-INFO\scripts\process_demo.py", line 14, in main
  File "C:\Python34\lib\multiprocessing\process.py", line 105, in start
    self._popen = self._Popen(self)
  File "C:\Python34\lib\multiprocessing\context.py", line 212, in _Popen
    return _default_context.get_context().Process._Popen(process_obj)
  File "C:\Python34\lib\multiprocessing\context.py", line 313, in _Popen
    return Popen(process_obj)
  File "C:\Python34\lib\multiprocessing\popen_spawn_win32.py", line 34, in __init__
    prep_data = spawn.get_preparation_data(process_obj._name)
  File "C:\Python34\lib\multiprocessing\spawn.py", line 173, in get_preparation_data
    main_mod_name = getattr(main_module.__spec__, "name", None)
AttributeError: 'module' object has no attribute '__spec__'

我创建了一个简单的测试文件，里面只有调用multiprocessing.Process的代码，问题显然出在这里。

process_demo.py

import multiprocessing

def worker():
    print("foooo")

def main(threads=4):
    procs = []

    for i in range(threads):
        p = multiprocessing.Process(target=worker)
        procs.append(p)
        p.start()

if __name__ == "__main__":
    multiprocessing.freeze_support()
    main()

设置文件：

from ez_setup import use_setuptools
use_setuptools()

from setuptools import setup

setup(name='procdemo',
      version='1.0',
      description='Some Demo',
      scripts=['bin/process_demo.py'],
      )

我该如何安全地在脚本中启动进程，而不影响setuptools的正常工作呢？

Answer 1

我不太确定有没有其他方法，不过如果你把这个Python脚本做成一个控制台应用程序，它就能正常工作，没有任何问题：

from ez_setup import use_setuptools
use_setuptools()

from setuptools import setup

setup(name='procdemo',
      version='1.0',
      description='Some Demo',
      scripts=['bin/process_demo.py'],
      entry_points = {'console_scripts': ['foobarfoo = process_demo:main']},
      )