python利用线程实现红绿灯功能

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灯，生成几个线程做车辆，车辆行驶按红灯停，绿灯行的规则。

 1 import threading,time
 2 import random
 3 def light():
 4     if not event.isSet():
 5         event.set() #wait就不阻塞 #绿灯状态
 6     count = 0
 7     while True:
 8         if count < 10:
 9             print('33[42;1m--green light on---33[0m')
10         elif count <13:
11             print('33[43;1m--yellow light on---33[0m')
12         elif count <20:
13             if event.isSet():
14                 event.clear()
15             print('33[41;1m--red light on---33[0m')
16         else:
17             count = 0
18             event.set() #打开绿灯
19         time.sleep(1)
20         count +=1
21 def car(n):
22     while 1:
23         time.sleep(random.randrange(10))
24         if  event.isSet(): #绿灯
25             print("car [%s] is running.." % n)
26         else:
27             print("car [%s] is waiting for the red light.." %n)
28 if __name__ == '__main__':
29     event = threading.Event()
30     Light = threading.Thread(target=light)
31     Light.start()
32     for i in range(3):
33         t = threading.Thread(target=car,args=(i,))
34         t.start()

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