python多线程中Lock()与RLock()锁 对python多线程中Lock()与RLock()锁详解
comprel 人气:0资源总是有限的,程序运行如果对同一个对象进行操作,则有可能造成资源的争用,甚至导致死锁
也可能导致读写混乱
锁提供如下方法:
1.Lock.acquire([blocking])
2.Lock.release()
3.threading.Lock() 加载线程的锁对象,是一个基本的锁对象,一次只能一个锁定,其余锁请求,需等待锁释放后才能获取
4.threading.RLock() 多重锁,在同一线程中可用被多次acquire。如果使用RLock,那么acquire和release必须成对出现,
调用了n次acquire锁请求,则必须调用n次的release才能在线程中释放锁对象
例如:
无锁:
#coding=utf8 import threading import time num = 0 def sum_num(i): global num time.sleep(1) num +=i print num print '%s thread start!'%(time.ctime()) try: for i in range(6): t =threading.Thread(target=sum_num,args=(i,)) t.start() except KeyboardInterrupt,e: print "you stop the threading" print '%s thread end!'%(time.ctime())
输出:
Sun May 28 20:54:59 2017 thread start! Sun May 28 20:54:59 2017 thread end! 01 3 710 15
结果显示混乱
引入锁:
#coding=utf8 import threading import time num = 0 def sum_num(i): lock.acquire() global num time.sleep(1) num +=i print num lock.release() print '%s thread start!'%(time.ctime()) try: lock=threading.Lock() list = [] for i in range(6): t =threading.Thread(target=sum_num,args=(i,)) list.append(t) t.start() for threadinglist in list: threadinglist.join() except KeyboardInterrupt,e: print "you stop the threading" print '%s thread end!'%(time.ctime())
结果:
Sun May 28 21:15:37 2017 thread start! 0 1 3 6 10 15 Sun May 28 21:15:43 2017 thread end!
其中:
lock=threading.Lock()加载锁的方法也可以换成lock=threading.RLock()
如果将上面的sum_num修改为:
lock.acquire() global num lock.acquire() time.sleep(1) num +=i lock.release() print num lock.release()
那么:
lock=threading.Lock() 加载的锁,则一直处于等待中,锁等待
而lock=threading.RLock() 运行正常
以上这篇对python多线程中Lock()与RLock()锁详解就是小编分享给大家的全部内容了,希望能给大家一个参考,也希望大家多多支持。
加载全部内容