python如何以分离模式运行进程

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

问题描述

这是一个例子:

from multiprocessing import Process
import time


def func():
    print('sub process is running')
    time.sleep(5)
    print('sub process finished')


if __name__ == '__main__':
    p = Process(target=func)
    p.start()
    print('done')

我希望主进程在启动子进程后立即终止.但是在打印出完成"之后，终端仍在等待......有没有办法做到这一点，以便主进程在打印出完成"后立即退出，而不是等待子进程?我在这里很困惑，因为我没有调用 p.join()

what I expect is that the main process will terminate right after it start a subprocess. But after printing out 'done', the terminal is still waiting....Is there any way to do this so that the main process will exit right after printing out 'done', instead of waiting for subprocess? I'm confused here because I'm not calling p.join()

解决方案

如果存在非守护进程.

通过在start()调用前设置daemon属性，可以使进程成为守护进程.

By setting, daemon attribute before start() call, you can make the process daemonic.

p = Process(target=func)
p.daemon = True  # <-----
p.start()
print('done')

注意:不会打印sub process finished消息；因为主进程将在退出时终止子进程.这可能不是你想要的.

NOTE: There will be no sub process finished message printed; because the main process will terminate sub-process at exit. This may not be what you want.

你应该做双叉:

import os
import time
from multiprocessing import Process


def func():
    if os.fork() != 0:  # <--
        return          # <--
    print('sub process is running')
    time.sleep(5)
    print('sub process finished')


if __name__ == '__main__':
    p = Process(target=func)
    p.start()
    p.join()
    print('done')

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