多线程代码

import threading,time
b = 50
l = threading.Lock()
def threadcode():
    global b
    print "Thread %s invoked" % threading.currentThread().getName()
    l.acquire()
    try:
        print "Thread %s runngin" % threading.currentThread().getName()
        time.sleep(2)
        b = b + 50
        print "Thread %s runngin set b to %s" % (threading.currentThread().getName(),b)
    finally:
        l.release()
print "Value of b at start of program:", b
childthreads = []
for i in range(1,5):
    t = threading.Thread(target=threadcode,name="Thread-%d"%i)  #这个方法不错哦。指定一个方法就是run里面做的事情了
    t.setDaemon(1)      #这个表示的是如果你父线程退出我子线程也要跟着退出
    t.start()
    childthreads.append(t)

for t in childthreads:
    t.join()                    #表示要等t执行完成之后再搪行
print "new value is ",b