在多处理中生成单例类

您的每个子进程都运行自己的Python解释器实例,因此 SingletonType 在一个进程中,不会与另一个进程中的进程共享其状态。这意味着一个只存在于一个进程中的真正单例将几乎没有用处,因为你将无法在其他进程中使用它:而你可以 manually share data between processes ,这仅限于基本数据类型(例如dict和list)。

#!/usr/bin/env python3

import multiprocessing
import os


def log(s):
    print('{}: {}'.format(os.getpid(), s))


class PseudoSingleton(object):

    def __init__(*args,**kwargs):
        if not shared_state:
            log('Initializating shared state')
            with shared_state_lock:
                shared_state['x'] = 1
                shared_state['y'] = 2
            log('Shared state initialized')
        else:
            log('Shared state was already initalized: {}'.format(shared_state))


def task():
    a = PseudoSingleton()


if __name__ == '__main__':
    # We need the __main__ guard so that this part is only executed in
    # the parent

    log('Communication setup')
    shared_state = multiprocessing.Manager().dict()
    shared_state_lock = multiprocessing.Lock()

    # create two process
    log('Start child processes')
    pro_1 = multiprocessing.Process(target=task)
    pro_2 = multiprocessing.Process(target=task)
    pro_1.start()
    pro_2.start()

    # Wait until processes have finished
    # See https://stackoverflow.com/a/25456494/857390
    log('Wait for children')
    pro_1.join()
    pro_2.join()

    log('Done')

这张照片

16194: Communication setup
16194: Start child processes
16194: Wait for children
16200: Initializating shared state
16200: Shared state initialized
16201: Shared state was already initalized: {'x': 1, 'y': 2}
16194: Done

然而,根据您的问题设置,使用其他进程间通信机制可能会有更好的解决方案。例如 Queue class