Python 实现红绿灯

一、通过Event来实现两个或多个线程间的交互，下面是一个红绿灯的例子，即起动一个线程做交通指挥信号灯，一个线程做车辆，车辆行驶按红灯停，绿灯行的规则。

#!/usr/bin/python

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

# 作者： Presley

# 时间： 2018-11-21

# 邮箱：[email protected]

# 这是我用来练习python线程锁的测试脚本

import threading,time

import random

def light():

    if not event.isSet(): #如果没有设定event

        event.set() #wait就不阻塞 #绿灯状态

    count = 0

    while True:

        if count < 10:

            print("\033[42;1m--green light on--\033[0m")

        elif count <13:

            print("\033[43;1m--yellow light on --\033[0m")

        elif count <20:

            if event.isSet():

                event.clear()

            print("\033[41;1m--red light on-- \033[0m")

        else:

            count = 0

            event.set() #打开绿灯

        time.sleep(1)

        count +=1

# def car(n):

#     while 1:

#         time.sleep(random.randrange(10))

#         if event.isSet(): #绿灯

#             print("car [%s] is running.." %n)

#         else:

#             print("car [%s] is waiting for the red light.." %n)

def car(n):    #no bug version

    while 1:

        time.sleep(1) #让车慢点if event.isSet(): #绿灯

            print("car [%s] is running.." %n)

        else:

            print("car [%s] is waiting for the red light.." %n)

            event.wait() #不断检查flag有没有被设定,如果没有设定就等着,这个是输入event等待时间，可以精确到毫秒级

if __name__ == "__main__":

    event = threading.Event()

    Light = threading.Thread(target=light)

    Light.start()

    for i in range(3):

        t = threading.Thread(target=car,args=(i,))

        t.start()

执行结果：

--green light on--

--green light on--

car [0] is running..

--green light on--

car [0] is running..

--green light on--

car [2] is running..

--green light on--

--green light on--

--green light on--

car [2] is running..

--green light on--

car [2] is running..

--green light on--

--green light on--

car [1] is running..

car [0] is running..

--yellow light on --

car [0] is running..

--yellow light on --

car [0] is running..

--yellow light on --

--red light on--

--red light on--

--red light on--

car [1] is waiting for the red light..

--red light on--

car [0] is waiting for the red light..

--red light on--

car [2] is waiting for the red light..

--red light on--

--red light on--

--green light on--

--green light on--

car [2] is running..

--green light on--

car [1] is running..

--green light on--

--green light on--

car [1] is running..

--green light on--

car [0] is running..

--green light on--

--green light on--
...