满足给定条件时如何终止python中的多进程？

Question

假设我有这个功能：

def f():  
    while True:          
        x = generate_something()  
        if x == condition:  
            return x

if __name__ == '__main__':
    p=Pool(4)

我想在多进程中运行此函数，当其中一个进程满足我的函数条件时，我希望所有其他进程停止。

Answer 1

您可以使用eventand terminatein ，multiprocessing因为您希望在子进程之一中满足条件后停止所有进程。

检查下面的工作示例，其中我正在创建两个进程，这些进程将检查变量的值x是否为 5。

一旦进程之一将值设置x为5，则事件被设置。

Event是set或unset在main代码中不断检查。

代码：

import random
import multiprocessing
import sys
import time

def generate_something():
    return random.choice(range(10))

def f(event):
    while True:
        x = generate_something()
        print "Value is ",x
        if x == 5:
            print "Got what I am searching for."
            event.set()
        time.sleep(2)

if __name__ == '__main__':

    jobs = []
    #Create Event
    event = multiprocessing.Event()

    #Create two processes
    for i in range(2):
        p = multiprocessing.Process(target=f,args=(event,))
        p.start()
        jobs.append(p)

    #Check whether event is set or not
    #When set close all child processes
    while True:
        if event.is_set():
            print "Exiting all child processess.."
            for i in jobs:
                #Terminate each process
                i.terminate()
            #Terminating main process
            sys.exit(1)
        time.sleep(2)

输出：

"C:\Program Files (x86)\Python27\python.exe" C:/Users/punddin/PycharmProjects/demo/a.py
Value is  4
Value is  2
Value is  7
Value is  6
Value is  3
Value is  4
Value is  8
Value is  3
Value is  8
Value is  1
Value is  9
Value is  9
Value is  1
Value is  6
Value is  5
Got what I am searching for.
Value is  6
Exiting all processess..