进程池

import multiprocessing
import time
def func(msg):
    print('start:', msg)
    time.sleep(3)
    print('end:', msg)
if __name__ == '__main__':
    # 初始化进程池参数为进程池最大进程数, 超过的必须等待已有的任务释放才能继续添加
    pool = multiprocessing.Pool(3)
    # 添加任务
    for i in range(6):
        pool.apply_async(func=func, args=('任务:%d' % i,))
    pool.close()
    pool.join()