multiprocessing: __mp_main__和__main__

multiprocess在不同的操作系统上创建子进程的方法是不一样的，表现形式也不一样。linux上用的是fork, mac/windows上用的是spawn。

示例

1.用fork创建子进程

import multiprocessing as mp


def child_process():
    print('Hi! My name is', __name__)


print('Hi! My name is', __name__)
if __name__ == '__main__':
    mp.set_start_method('fork')
    mp.Process(target=child_process, name="child process").start()

运行结果：

Hi! My name is __main__
Hi! My name is __main__

2.用spawn

import multiprocessing as mp


def child_process():
    print('Hi! My name is', __name__)


print('Hi! My name is', __name__)
if __name__ == '__main__':
    # mp.set_start_method('fork')
    mp.Process(target=child_process, name="child process").start()

运行结果：

Hi! My name is __main__
Hi! My name is __mp_main__
Hi! My name is __mp_main__

spawn启动子进程的时候，会先运行一下父进程的内容，在运行target函数