Python 多线程2

守护进程

import threading
from time import ctime,sleep
def music(func):
    for i in range(2):
        print "I --> %s. %s" %(func,ctime())
        sleep(1)
def movie(func):
    for i in range(2):
        print "I --> %s! %s" %(func,ctime())
        sleep(5)
threads = []
t1 = threading.Thread(target=music,args=(u'Music',))
threads.append(t1)
t2 = threading.Thread(target=movie,args=(u'Movie',))
threads.append(t2)
if __name__ == '__main__':
    for t in threads:
        t.setDaemon(True)
        t.start()
    print "MainThread is over %s!" %ctime()

I –> Music. Mon Mar 06 18:43:39 2017
I –> Movie! Mon Mar 06 18:43:39 2017
MainThread is over Mon Mar 06 18:43:39 2017!
I –> Music. Mon Mar 06 18:43:40 2017
I –> Movie! Mon Mar 06 18:43:44 2017

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。

创建进程

import threading
from time import ctime,sleep
def music(func):
    for i in range(2):
        print 'I --> %s!  %s' %(func,ctime())
        sleep(1)
def movie(func):
    for i in range(2):
        print 'I --> %s!  %s'%(func,ctime())
        sleep(5)
threads = []
t1 = threading.Thread(target = music,args =(u'Music',))
threads.append(t1)
t2 = threading.Thread(target = movie,args =(u'Movie',))
threads.append(t2)
if __name__=='__main__':
    for t in threads:
        t.setDaemon(True)
        t.start()
    t.join()
    print 'MainThread is over!  %s' %ctime()

输出结果：

I –> Music! Mon Mar 06 19:02:27 2017
I –> Movie! Mon Mar 06 19:02:27 2017
I –> Music! Mon Mar 06 19:02:28 2017
I –> Movie! Mon Mar 06 19:02:32 2017
MainThread is over! Mon Mar 06 19:02:37 2017

我们只对上面的程序加了个join()方法，用于等待线程终止。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。