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python避免死锁方法实例分析

作者:佚名    责任编辑:admin    更新时间:2022-06-22

   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

  ?

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 import threading ,time a = 5 alock = threading.Lock() b = 5 block = 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:

  ?

1 2 3 4 thread1 acquiring lock a thread2 acquiring lock b thread1 acquiring lock b thread2 acquiring lock a

  希望本文所述对大家的Python程序设计有所帮助。