python同步锁

加上同步锁后,锁住的线程代码必须执行完后,才允许另一个线程开启.下面的代码显示了同步锁的应用

import time,threading
def subNum():
    global num
    r.acquire()
    temp = num
    num = temp - 1
    r.release()
if __name__ == '__main__':
    num = 100
    r = threading.Lock()
    for i in range(100):
        t = threading.Thread(target = subNum)
        t.start()

    print('the final number is:%s'%num)