#!/usr/bin/env python

# encoding: utf-8  

# Date: 2018/6/18

from threading import Thread,Semaphore,currentThread

import time

import random

sm = Semaphore(3)

def task():

    # sm.acquire()

    # print('%s in ' % currentThread().getName())

    # sm.release()

    # 等价于以上代码

    with sm:

        print('%s in ' % currentThread().getName())

        time.sleep(random.randint(1, 3))

if __name__ == '__main__':

    for i in range(10):

        t = Thread(target=task)

        t.start()