Python多线程之event

写在前面的话

看了网上一些大牛相关博客，不是很理解，内核对象啊什么的。这篇博客用白话记录自己的学习过程以及一些理解。

event精粹

概述

事件(event)用于线程间同步和通信。比如线程A要完成某一任务(event)线程B才能执行后面的代码，怎么实现呢，就是用event。

event常用方法 释义 set() 开始一个事件 wait() 如果未设置set状态会一直等待，否则过 clear() 清除set状态 isSet() 是否设置set状态

注意：
wait方法是阻塞的
设置完set后要使用clear方法，否则wait为真，不会等待

上代码

#!/usr/bin python#coding=utf-8import threadingimport timedef producer():    print u'等人来买包子....'    event.wait()    #event.clear()    print event.isSet()    print u'chef:sb is coming for baozi...'    print u'chef:making a baozi for sb...'    time.sleep(5)    print u'chef:你的包子好了...'    event.set() def consumer():    print u'chenchao:去买包子....'    event.set()    time.sleep(2)    print 'chenchao:waiting for baozi to be ready...'    print event.wait()    print u'chenchao:哎呀真好吃....'event = threading.Event()p = threading.Thread(target=producer,args=())c = threading.Thread(target=consumer,args=())p.start()c.start()

clear()注释掉的结果

等人来买包子....chenchao:去买包子....Truechef:sb is coming for baozi...chef:making a baozi for sb...chenchao:waiting for baozi to be ready...Truechenchao:哎呀真好吃....chef:你的包子好了...

最后两行显然有问题，包子还没好就可以print了，要使用clear
方法清除设置的set状态。

#!/usr/bin python#coding=utf-8import threadingimport timedef producer():    print u'等人来买包子....'    event.wait()    event.clear()    print event.isSet()    print u'chef:sb is coming for baozi...'    print u'chef:making a baozi for sb...'    time.sleep(5)    print u'chef:你的包子好了...'    event.set() def consumer():    print u'chenchao:去买包子....'    event.set()    time.sleep(2)    print 'chenchao:waiting for baozi to be ready...'    print event.wait()    print u'chenchao:哎呀真好吃....'event = threading.Event()p = threading.Thread(target=producer,args=())c = threading.Thread(target=consumer,args=())p.start()c.start()

结果是这样的

等人来买包子....chenchao:去买包子....Falsechef:sb is coming for baozi...chef:making a baozi for sb...chenchao:waiting for baozi to be ready...chef:你的包子好了...Truechenchao:哎呀真好吃....

模拟异步模型中的select

#!/usr/bin python#coding=utf-8import threadingimport timedef producer():    print u'等人来买包子....'    event.wait()    event.clear()    print event.isSet()    print u'chef:sb is coming for baozi...'    print u'chef:making a baozi for sb...'    time.sleep(5)    print u'chef:你的包子好了...'    event.set() def consumer():    print u'chenchao:去买包子....'    event.set()    time.sleep(2)    print 'chenchao:waiting for baozi to be ready...'    while True:        if event.isSet():            print u'真好吃...'            break        else:            print u'好慢啊...'            time.sleep(1)#相当于去做自己的事去了event = threading.Event()p = threading.Thread(target=producer,args=())c = threading.Thread(target=consumer,args=())p.start()c.start()

结果

等人来买包子....chenchao:去买包子....Falsechef:sb is coming for baozi...chef:making a baozi for sb...chenchao:waiting for baozi to be ready...好慢啊...好慢啊...好慢啊...好慢啊...chef:你的包子好了...真好吃...