python 进程池

#!/usr/bin/env python
# -*- coding: utf-8 -*-
"""
@version: 001
@author: jianpan
@file: test1.py
@time: 2017/6/4 16:14
"""

# coding: utf-8
import multiprocessing
import time
import os
import psutil
def func(msg):
    print "msg:", msg
    # print os.getgid()
    time.sleep(3)
    print "end"


if __name__ == "__main__":
    pool = multiprocessing.Pool(processes=3)
    print os.getpid()
    for i in xrange(3):
        msg = "hello %d" % (i)
        pool.apply_async(func, (msg,))  # 维持执行的进程总数为processes，当一个进程执行完毕后会添加新的进程进去

    print "Mark~ Mark~ Mark~~~~~~~~~~~~~~~~~~~~~~"
    t = psutil.Process()

    pool.close()
    children = t.children()
    for child in children:
        print('Child pid is {}'.format(child.pid))
    pool.join()  # 调用join之前，先调用close函数，否则会出错。执行完close后不会有新的进程加入到pool,join函数等待所有子进程结束
    print "Sub-process(es) done."