python多处理管理器列表错误:[Errno 2]没有这样的文件或目录

2022-01-12 00:00:00 python multiprocessing

问题描述

我在 python 中编写了一个多处理程序.我使用 multiprocessing.Manager().list() 在子进程中共享列表.首先，我在主流程中添加了一些任务.然后，启动一些子进程来执行共享列表中的任务，子进程也将任务添加到共享列表中.但我得到了一个例外:

I worte a multiprocessing program in python. I use multiprocessing.Manager().list() to share list within subprocess. At first, I add some tasks in main process. And then, start some subprocesses to do tasks which in the shared list, the subprocesses also add tasks to the shared list. But I got a exception as follow:

    Traceback (most recent call last):
      File "/usr/lib64/python2.6/multiprocessing/process.py", line 232, in _bootstrap
        self.run()
      File "/usr/lib64/python2.6/multiprocessing/process.py", line 88, in run
        self._target(*self._args, **self._kwargs)
      File "gen_friendship.py", line 255, in worker
        if tmpu in nodes:
      File "<string>", line 2, in __contains__
      File "/usr/lib64/python2.6/multiprocessing/managers.py", line 722, in _callmethod
        self._connect()
      File "/usr/lib64/python2.6/multiprocessing/managers.py", line 709, in _connect
        conn = self._Client(self._token.address, authkey=self._authkey)
      File "/usr/lib64/python2.6/multiprocessing/connection.py", line 143, in Client
        c = SocketClient(address)
      File "/usr/lib64/python2.6/multiprocessing/connection.py", line 263, in SocketClient
        s.connect(address)
      File "<string>", line 1, in connect
    error: [Errno 2] No such file or directory

我发现了一些关于如何在 python 多处理中使用共享列表的信息，例如 这个.但还是有一些例外.我不知道异常的含义.而common list和manager.list有什么区别?

I find something about how to use shared list in python multiprocessing like this. But still have some exception. I have no idea of the meaning of the exception. And what's the difference between the common list and the manager.list?

代码如下:

    nodes = multiprocessing.Manager().list()

    lock = multiprocessing.Lock()

    AMOUNT_OF_PROCESS = 10

    def worker():
        lock.acquire()
        nodes.append(node)
        lock.release()

    if __name__ == "__main__":

        for i in range(i):
            nodes.append({"name":"username", "group":1})

        processes = [None for i in range(AMOUNT_OF_PROCESS)]

        for i in range(AMOUNT_OF_PROCESS):
            processes[i] = multiprocessing.Process(taget=worker, args=())
            processes[i].start()

解决方案

问题是你的主进程在你启动所有工作进程后立即退出，这会关闭你的 Manager.当您的 Manager 关闭时，没有一个孩子可以使用您传递给他们的共享列表.您可以通过使用 join 等待所有孩子完成来修复它.只需确保在调用 join 之前确实 start 所有进程:

The problem is that your main process is exiting immediately after you start all your worker processes, which shuts down your Manager. When your Manager shuts down, none of the children can use the shared list you passed into them. You can fix it by using join to wait for all the children to finish. Just make sure you actually start all your processes prior to calling join:

for i in range(AMOUNT_OF_PROCESS):
    processes[i] = multiprocessing.Process(target=worker, args=())
    processes[i].start()
for process in processes:
    process.join()

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