如何恢复传递给 multiprocessing.Process 的函数的返回值? [英] How can I recover the return value of a function passed to multiprocessing.Process?

问题描述

在下面的示例代码中，我想恢复函数worker 的返回值.我该怎么做呢?这个值存储在哪里?

In the example code below, I'd like to recover the return value of the function worker. How can I go about doing this? Where is this value stored?

示例代码:

import multiprocessing

def worker(procnum):
    '''worker function'''
    print str(procnum) + ' represent!'
    return procnum


if __name__ == '__main__':
    jobs = []
    for i in range(5):
        p = multiprocessing.Process(target=worker, args=(i,))
        jobs.append(p)
        p.start()

    for proc in jobs:
        proc.join()
    print jobs

输出:

0 represent!
1 represent!
2 represent!
3 represent!
4 represent!
[<Process(Process-1, stopped)>, <Process(Process-2, stopped)>, <Process(Process-3, stopped)>, <Process(Process-4, stopped)>, <Process(Process-5, stopped)>]

我似乎无法在存储在 jobs 中的对象中找到相关属性.

I can't seem to find the relevant attribute in the objects stored in jobs.

推荐答案

使用 共享变量 进行通信.例如像这样:

Use shared variable to communicate. For example like this:

import multiprocessing


def worker(procnum, return_dict):
    """worker function"""
    print(str(procnum) + " represent!")
    return_dict[procnum] = procnum


if __name__ == "__main__":
    manager = multiprocessing.Manager()
    return_dict = manager.dict()
    jobs = []
    for i in range(5):
        p = multiprocessing.Process(target=worker, args=(i, return_dict))
        jobs.append(p)
        p.start()

    for proc in jobs:
        proc.join()
    print(return_dict.values())

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