【python学习】多线程锁 生产者和消费者问题 

 1 #!/usr/bin/env python
 2 # -*- coding:utf-8 -*-
 3 
 4 import threading
 5 import random, time, Queue
 6 
 7 MAX_SIZE = 5
 8 SHARE_Q = []  #模拟共享队列
 9 CONDITION = threading.Condition()
10 
11 class Producer(threading.Thread) :
12 
13     def run(self) :
14         products = range(5)
15         global SHARE_Q
16         while True :
17             CONDITION.acquire()
18             if len(SHARE_Q) == 5 :
19                 print "Queue is full.."
20                 CONDITION.wait()
21                 print "Consumer have comsumed something"
22             product = random.choice(products)
23             SHARE_Q.append(product)
24             print "Producer : ", product
25             CONDITION.notify()
26             CONDITION.release()
27             time.sleep(random.random())
28 
29 class Consumer(threading.Thread) :
30 
31     def run(self) :
32         global SHARE_Q
33         while True:
34             CONDITION.acquire()
35             if not SHARE_Q :
36                 print "Queue is Empty..."
37                 CONDITION.wait()
38                 print "Producer have producted something"
39             product = SHARE_Q.pop(0)
40             print "Consumer :", product
41             CONDITION.notify()
42             CONDITION.release()
43             time.sleep(random.random())
44 
45 def main() :
46     producer = Producer()
47     consumer = Consumer()
48     producer.start()
49     consumer.start()
50 
51 if __name__ == '__main__':
52     main()

Condition

条件变量中有acquire()和release方法用来调用锁的方法, 有wait(), notify(), notifyAll()方法, 后面是三个方法必须在获取锁的情况下调用, 否则产生RuntimeError错误.

  • 当一个线程获得锁后, 发现没有期望的资源或者状态, 就会调用wait()阻塞, 并释放已经获得锁, 知道期望的资源或者状态发生改变
  • 当一个线程获得锁, 改变了资源或者状态, 就会调用notify()和notifyAll()去通知其他线程,
posted @ 2017-04-10 21:09  vxee  阅读(120)  评论(0)  编辑  收藏  举报