Python 单线程多线程

- 日理万妓 2022-06-09 06:55 362阅读 0赞

早期的操作系统处理问题都是单任务的，同时只能执行一个任务，按顺序执行。

**执行结果：**

I was listening to 南方姑娘. Wed Aug 30 15:35:15 2017  
I was listening to 南方姑娘. Wed Aug 30 15:35:16 2017  
I was at the 战狼2! Wed Aug 30 15:35:17 2017  
I was at the 战狼2! Wed Aug 30 15:35:22 2017  
I was at the 阿里巴巴! Wed Aug 30 15:35:27 2017  
I was at the 阿里巴巴! Wed Aug 30 15:35:31 2017  
I was at the 使用wechat! Wed Aug 30 15:35:35 2017  
I was at the 使用wechat! Wed Aug 30 15:35:38 2017  
all over Wed Aug 30 15:35:41 2017  
**total time is 26.0033179014**

#coding=utf-8
    import threading
    from time import ctime,sleep,clock
    
    def music(func):
        for i in range(2):
            print "I was listening to %s. %s" %(func,ctime())
            sleep(1)
    
    def movie(func):
        for i in range(2):
            print "I was at the %s! %s" %(func,ctime())
            sleep(5)
            
    def surfInternet(func):
        for i in range(2):
            print "I was at the %s! %s" %(func,ctime())
            sleep(4)
            
    def talk(func):
        for i in range(2):
            print "I was at the %s! %s" %(func,ctime())
            sleep(3)
    threads = []
    t1 = threading.Thread(target=music,args=(u'南方姑娘',))
    threads.append(t1)
    t2 = threading.Thread(target=movie,args=(u'战狼2',))
    threads.append(t2)
    t3 = threading.Thread(target=surfInternet,args=(u'阿里巴巴',))
    threads.append(t3)
    t4 = threading.Thread(target=talk,args=(u'使用wechat',))
    threads.append(t4)
    
    if __name__ == '__main__':
        start = clock()
        for t in threads:
            t.setDaemon(True)
            t.start() 
        t.join()#在子线程完成运行之前，这个子线程的父线程将一直被阻塞。
        end = clock()
        print "all over %s" %ctime()
        print "total time is %s" %(end-start)

**执行结果：**

I was listening to 南方姑娘. Wed Aug 30 15:36:41 2017  
I was at the 战狼2! Wed Aug 30 15:36:41 2017  
I was at the 阿里巴巴! Wed Aug 30 15:36:41 2017  
I was at the 使用wechat! Wed Aug 30 15:36:41 2017  
I was listening to 南方姑娘. Wed Aug 30 15:36:42 2017  
I was at the 使用wechat! Wed Aug 30 15:36:44 2017  
I was at the 阿里巴巴! Wed Aug 30 15:36:45 2017  
I was at the 战狼2! Wed Aug 30 15:36:46 2017  
all over Wed Aug 30 15:36:47 2017  
**total time is 6.00455547207**

*从单线程的26s，减少到多线程的6s,节约20s时间。*

*threads = \[\]*

*t1 = threading.Thread(target=music,args=(u'**南方姑娘'**,))*

*threads.append(t1)*

*创建了threads数组，创建线程t1,使用threading.Thread()方法，在这个方法中调用music方法target=music，args方法对music进行传参。 把创**建好的线程t1装到threads数组中。**接着以同样的方式创建线程t2,t3,t4，并把t2,t3,t4也装到threads数组。*

*for t in threads:*

*t.setDaemon(True)*

*t.start()*

*最后通过for循环遍历数组。（数组被装载了t1,t2,t3**和t4四**个线程）*

setDaemon()

setDaemon(True)将线程声明为守护线程，必须在start() 方法调用之前设置，如果不设置为守护线程程序会被无限挂起。子线程启动后，父线程也继续执行下去，当父线程执行完最后一条语句print "all over %s" %ctime()后，没有等待子线程，直接就退出了，同时子线程也一同结束。

start()

开始线程活动。

join*()*的作用是，在子线程完成运行之前，这个子线程的父线程将一直被阻塞。