python避免死锁方法实例分析

本文实例讲述了python避免死锁方法。分享给大家供大家参考。具体分析如下：

当两个或者更多的线程在等待资源的时候就会产生死锁，两个线程相互等待。
在本文实例中 thread1 等待thread2释放block , thread2等待thtead1释放ablock，
 
避免死锁的原则：

1. 一定要以一个固定的顺序来取得锁，这个列子中，意味着首先要取得alock, 然后再去block

2. 一定要按照与取得锁相反的顺序释放锁，这里，应该先释放block,然后是alock

import threading ,timea = 5alock = threading.Lock()b = 5block = threading.Lock()def thread1calc():  print "thread1 acquiring lock a"  alock.acquire()  time.sleep(5)  print "thread1 acquiring lock b"  block.acquire()  a+=5  b+=5  print "thread1 releasing both locks"  block.release()  alock.release()def thread2calc():  print "thread2 acquiring lock b"  block.acquire()  time.sleep(5)  print "thread2 acquiring lock a"  alock.acquire()  time.sleep(5)  a+=10  b+=10  print "thread2 releasing both locks"  block.release()  alock.release()t = threading.Thread(target = thread1calc)t.setDaemon(1)t.start()t = threading.Thread(target = thread2calc)t.setDaemon(2)t.start()while 1:  time.sleep(300)

输出：

thread1 acquiring lock athread2 acquiring lock bthread1 acquiring lock bthread2 acquiring lock a

希望本文所述对大家的Python程序设计有所帮助。