Python 多处理模块 freeze_support() line can be omitted error Windows

Question

我正在尝试在 python 中进行多处理。我最初在 Ubuntu 系统上编写了这个测试代码，并且执行得很好。当我尝试在 Windows 中运行相同的程序时，出现以下错误:

Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "C:\Users\Peri\AppData\Local\Programs\Python\Python38-32\lib\multiprocessing\spawn.py", line 116, in spawn_main
    exitcode = _main(fd, parent_sentinel)
  File "C:\Users\Peri\AppData\Local\Programs\Python\Python38-32\lib\multiprocessing\spawn.py", line 125, in _main
    prepare(preparation_data)
  File "C:\Users\Peri\AppData\Local\Programs\Python\Python38-32\lib\multiprocessing\spawn.py", line 236, in prepare
    _fixup_main_from_path(data['init_main_from_path'])
  File "C:\Users\Peri\AppData\Local\Programs\Python\Python38-32\lib\multiprocessing\spawn.py", line 287, in _fixup_main_from_path
    main_content = runpy.run_path(main_path,
  File "C:\Users\Peri\AppData\Local\Programs\Python\Python38-32\lib\runpy.py", line 263, in run_path
    return _run_module_code(code, init_globals, run_name,
  File "C:\Users\Peri\AppData\Local\Programs\Python\Python38-32\lib\runpy.py", line 96, in _run_module_code
    _run_code(code, mod_globals, init_globals,
  File "C:\Users\Peri\AppData\Local\Programs\Python\Python38-32\lib\runpy.py", line 86, in _run_code
    exec(code, run_globals)
  File "C:\Users\Peri\Documents\Heatloss Project\OGI_u_value_module-master\test.py", line 21, in <module>
    main()
  File "C:\Users\Peri\Documents\Heatloss Project\OGI_u_value_module-master\test.py", line 15, in main
    p1.start()
  File "C:\Users\Peri\AppData\Local\Programs\Python\Python38-32\lib\multiprocessing\process.py", line 121, in start
    self._popen = self._Popen(self)
  File "C:\Users\Peri\AppData\Local\Programs\Python\Python38-32\lib\multiprocessing\context.py", line 224, in _Popen
    return _default_context.get_context().Process._Popen(process_obj)
  File "C:\Users\Peri\AppData\Local\Programs\Python\Python38-32\lib\multiprocessing\context.py", line 326, in _Popen
    return Popen(process_obj)
  File "C:\Users\Peri\AppData\Local\Programs\Python\Python38-32\lib\multiprocessing\popen_spawn_win32.py", line 45, in __init__
    prep_data = spawn.get_preparation_data(process_obj._name)
  File "C:\Users\Peri\AppData\Local\Programs\Python\Python38-32\lib\multiprocessing\spawn.py", line 154, in get_preparation_data
    _check_not_importing_main()
  File "C:\Users\Peri\AppData\Local\Programs\Python\Python38-32\lib\multiprocessing\spawn.py", line 134, in _check_not_importing_main
    raise RuntimeError('''
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 "<string>", line 1, in <module>
  File "C:\Users\Peri\AppData\Local\Programs\Python\Python38-32\lib\multiprocessing\spawn.py", line 116, in spawn_main
    exitcode = _main(fd, parent_sentinel)
  File "C:\Users\Peri\AppData\Local\Programs\Python\Python38-32\lib\multiprocessing\spawn.py", line 125, in _main
    prepare(preparation_data)
  File "C:\Users\Peri\AppData\Local\Programs\Python\Python38-32\lib\multiprocessing\spawn.py", line 236, in prepare
    _fixup_main_from_path(data['init_main_from_path'])
  File "C:\Users\Peri\AppData\Local\Programs\Python\Python38-32\lib\multiprocessing\spawn.py", line 287, in _fixup_main_from_path
    main_content = runpy.run_path(main_path,
  File "C:\Users\Peri\AppData\Local\Programs\Python\Python38-32\lib\runpy.py", line 263, in run_path
    return _run_module_code(code, init_globals, run_name,
  File "C:\Users\Peri\AppData\Local\Programs\Python\Python38-32\lib\runpy.py", line 96, in _run_module_code
    _run_code(code, mod_globals, init_globals,
  File "C:\Users\Peri\AppData\Local\Programs\Python\Python38-32\lib\runpy.py", line 86, in _run_code
    exec(code, run_globals)
  File "C:\Users\Peri\Documents\Heatloss Project\OGI_u_value_module-master\test.py", line 21, in <module>
    main()
  File "C:\Users\Peri\Documents\Heatloss Project\OGI_u_value_module-master\test.py", line 15, in main
    p1.start()
  File "C:\Users\Peri\AppData\Local\Programs\Python\Python38-32\lib\multiprocessing\process.py", line 121, in start
    self._popen = self._Popen(self)
  File "C:\Users\Peri\AppData\Local\Programs\Python\Python38-32\lib\multiprocessing\context.py", line 224, in _Popen
    return _default_context.get_context().Process._Popen(process_obj)
  File "C:\Users\Peri\AppData\Local\Programs\Python\Python38-32\lib\multiprocessing\context.py", line 326, in _Popen
    return Popen(process_obj)
  File "C:\Users\Peri\AppData\Local\Programs\Python\Python38-32\lib\multiprocessing\popen_spawn_win32.py", line 45, in __init__
    prep_data = spawn.get_preparation_data(process_obj._name)
  File "C:\Users\Peri\AppData\Local\Programs\Python\Python38-32\lib\multiprocessing\spawn.py", line 154, in get_preparation_data
    _check_not_importing_main()
  File "C:\Users\Peri\AppData\Local\Programs\Python\Python38-32\lib\multiprocessing\spawn.py", line 134, in _check_not_importing_main
    raise RuntimeError('''
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.

代码非常基础，只有打印文本和退出两个进程

from multiprocessing import Process
    
def process1(text):
    return print(text)
    
def process2(text):
    return print(text)
    
def main():
    p1 = Process(target=process1, args=('Test1', ))
    p2 = Process(target=process2, args=('Test2', ))
    p1.start()
    p2.start()
    p1.join()
    p2.join()
    
main()

我无法理解 Windows 中出了什么问题？

Answer 1

您很可能想先调用其中一个过程，然后再调用另一个过程，但不要执行p1.join() p2.join() 因为这只会让主程序停止，直到子进程完成。这将起作用:

from multiprocessing import Process


def process1(text):
    return print(text)

def process2(text):
    return print(text)

def main():

   p1 = Process(target=process1, args=('Test1', ))
    p2 = Process(target=process2, args=('Test2', ))
    p1.start()
    p2.start()

if __name__ == '__main__':
    main()