使用多处理从不同的进程追加到同一个列表 [英] Appending to the same list from different processes using multiprocessing

问题描述

我需要使用 multiprocessing 将来自不同进程的对象附加到一个列表 L ，但它返回空列表.如何让许多进程使用多处理附加到列表 L?

I need to append objects to one list L from different processes using multiprocessing , but it returns empty list. How can I let many processes append to list L using multiprocessing?

#!/usr/bin/python
from multiprocessing import Process

L=[]
def dothing(i,j):
    L.append("anything")
    print i

if __name__ == "__main__":
    processes=[]
    for i in range(5):
        p=Process(target=dothing,args=(i,None))
        p.start()
        processes.append(p)
    for p in processes:
        p.join()

print L

推荐答案

全局变量在进程之间不共享.

Global variables are not shared between processes.

您需要使用 multiprocessing.Manager.list:

You need to use multiprocessing.Manager.list:

from multiprocessing import Process, Manager

def dothing(L, i):  # the managed list `L` passed explicitly.
    L.append("anything")

if __name__ == "__main__":
    with Manager() as manager:
        L = manager.list()  # <-- can be shared between processes.
        processes = []
        for i in range(5):
            p = Process(target=dothing, args=(L,i))  # Passing the list
            p.start()
            processes.append(p)
        for p in processes:
            p.join()
        print L

参见进程间共享状态¶(服务器进程部分).

这篇关于使用多处理从不同的进程追加到同一个列表的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！