# !usr/bin/env python3

# -*- coding:utf-8 -*-

import os

import random

import time

from multiprocessing import Pool

from multiprocessing import Process

# 多进程 multiprocessing

# 1.1 创建子进程

print('ABC')

def run_proc(name):

print('Run child process %s (%s)...' % (name, os.getpid()))

if __name__ == '__main__':

print('Parent process %s.' % os.getpid())

p = Process(target=run_proc, args=('test',)) # 创建一个进程实例

print('Child process will start.')

p.start() # 用start()方法启动

p.join() # join()方法等待子进程结束后再继续往下运行，通常用于进程间的同步

print('Child process end.')

# 2.1 进程池 Pool

print('ABC')

def long_time_task(name):

print('Task %s runs %0.2f seconds.' % (name, (end - start)))

if __name__ == '__main__':

print('Parent process %s.' % os.getpid())

p = Pool(9) # 限制同时运行的进程数最多为9个，默认大小是CPU核数

for i in range(8):

p.apply_async(long_time_task, args=(i,)) # apply_async 是异步非阻塞，不用等待当前进程执行完毕，随时根据系统调度来进行进程切换。

print('Waiting for all subprocesses done...')

p.close() # close 方法后不能继续添加新的子进程了

p.join()

print('All subprocesses done.')