Python：如何在单独的进程中调用方法

Question

我想在一个单独的进程中启动 ActorCore 方法，然后处理到达该 ActorCore 的消息。由于某种原因，此代码无法正常工作。

import queue
from multiprocessing import Process


class NotMessage(Exception):
    def __str__(self):
        return 'NotMessage exception'


class Message(object):

    def Do(self, Actor):
        # Do some stuff to the actor
        pass

    def __str__(self):
        return 'Generic message'


class StopMessage(Message):

    def Do(self, Actor):
        Actor.__stopped = True

    def __str__(self):
        return 'Stop message'


class Actor(object):
    __DebugName = ''
    __MsgQ = None
    __stopped = False

    def __init__(self, Name):
        self.__DebugName = Name
        self.__MsgQ = queue.Queue()

    def LaunchActor(self):
        p = Process(target=self.ActorCore)
        p.start()
        return self.__MsgQ

    def ActorCore(self):
        while not self.__stopped:
            Msg = self.__MsgQ.get(block=True)
            try:
                Msg.Do(self)
                print(Msg)
            except NotMessage as e:
                print(str(e), ' occurred in ', self.__DebugName)


def main():
    joe = Actor('Joe')
    msg = Message()
    stop = StopMessage()
    qToJoe = joe.LaunchActor()
    qToJoe.put(msg)
    qToJoe.put(msg)
    qToJoe.put(stop)

if __name__ == '__main__':
    main()

运行时出现奇怪的错误：

Traceback (most recent call last):
  File "C:/Users/plkruczp/PycharmProjects/ActorFramework/Actor/Actor.py", line 64, in <module>
    main()
  File "C:/Users/plkruczp/PycharmProjects/ActorFramework/Actor/Actor.py", line 58, in main
    qToJoe = joe.LaunchActor()
  File "C:/Users/plkruczp/PycharmProjects/ActorFramework/Actor/Actor.py", line 40, in LaunchActor
    p.start()
  File "C:\Program Files\Python35\lib\multiprocessing\process.py", line 105, in start
    self._popen = self._Popen(self)
  File "C:\Program Files\Python35\lib\multiprocessing\context.py", line 212, in _Popen
    return _default_context.get_context().Process._Popen(process_obj)
  File "C:\Program Files\Python35\lib\multiprocessing\context.py", line 313, in _Popen
    return Popen(process_obj)
  File "C:\Program Files\Python35\lib\multiprocessing\popen_spawn_win32.py", line 66, in __init__
    reduction.dump(process_obj, to_child)
  File "C:\Program Files\Python35\lib\multiprocessing\reduction.py", line 59, in dump
    ForkingPickler(file, protocol).dump(obj)
TypeError: can't pickle _thread.lock objects

请帮忙！我什么都试过了:(

Answer 1

只需使用队列而不是队列：

删除import queue 并将Queue 添加到from multiprocessing 喜欢：

from multiprocessing import Process,Queue

然后将self.__MsgQ = queue.Queue()更改为self.__MsgQ = Queue()

这就是你需要做的所有事情来让它工作，其余的对你的情况是一样的。

编辑、解释：

queue.Queue 只是线程安全的，multiprocessing 实际上会产生另一个进程。因此，附加的multiprocessing.Queue 也被实现为进程安全的。作为另一种选择，如果需要多线程，threading 库可以与queue.Queue 一起使用：https://docs.python.org/dev/library/threading.html#module-threading

其他信息：

另一个并行化选项是joblib，根据您的进一步要求，可以将生成定义为进程或线程：https://joblib.readthedocs.io/