Events事件
Events是一个简单的同步对象，
事件表示一个内部标志和线程
可以等待设置标志，或设置或清除标志本身。
Events使用
生成event对象
event = threading.Event()
设置标志位
event.set()
清空标志位
event.clear()
等待设置标志位 如果标志位没有设置就一直等待
event.wait()
如果设置了标记，等待方法什么也不做。
如果标记被清除，等待将阻塞，直到它再次被设置。
任何数量的线程都可以等待相同的事件。
标志位被设定，代表绿灯，直接通行。
标志位被清空，代表红灯，wait等待变绿灯。等待标志位在设定。
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。
import threadingimport timeevent = threading.Event()def lighter(): count = 0 event.set() # 变绿灯 while True: if count >5 and count < 10 : #改红灯 event.clear() #清空标志位 print("\033[41;1mred light is on...\033[0m") elif count >10: event.set() # 变绿灯 count = 0 else: print("\033[42;1mgreen light is on...\033[0m") event.set() # 变绿灯 time.sleep(1) count+=1def car(name): while True: if event.is_set(): #代表绿灯 print("[%s] runing..."% name) time.sleep(1) else: print("[%s] sees red light,waiting..."% name) event.wait() print("[%s] green light is on,start going...")light = threading.Thread(target=lighter,)light.start()car1 = threading.Thread(target=car,args=("Tesla",))car1.start() 运行结果：
1 green light is on... 2 [Tesla] runing... 3 green light is on... 4 [Tesla] runing... 5 [Tesla] runing... 6 green light is on... 7 [Tesla] runing... 8 green light is on... 9 green light is on...10 [Tesla] runing...11 green light is on...12 [Tesla] runing...13 [Tesla] runing...14 red light is on...15 [Tesla] sees red light,waiting...16 red light is on...17 red light is on...18 red light is on...19 green light is on...20 [%s] green light is on,start going...21 [Tesla] runing...22 [Tesla] runing...23 green light is on...24 [Tesla] runing...25 green light is on...26 [Tesla] runing...27 green light is on...28 [Tesla] runing...29 [Tesla] runing...30 green light is on...31 green light is on...32 [Tesla] runing...33 [Tesla] runing...34 red light is on...35 [Tesla] sees red light,waiting...