python lock 同步问题

ytmayer

请教各位大神，如果两个线程同时去做 lock.acquire() ，都可以成功，从而导致同步问题。
是我代码有误吗？ 还是python线程有Lock的个数限制 (实际代码中有多个lock)
示例代码如下：  (估计要去掉sleep的代码/加大range范围才会跑出来)

1. import sys, os, re, time
   
2. import threading
   
3. 
   
4. class sockThd(threading.Thread):
   
5.     def __init__(self):
   
6.         self.lock=threading.Semaphore()
   
7.         #self.lock=threading.Lock()
   
8.         threading.Thread.__init__(self)
   
9.          
   
10.     def recv_func(self, id):
    
11.         print "before acquire:recv_func(): " + str(id)
    
12.         self.lock.acquire()
    
13.         print "after acquire:recv_func(): " + str(id)
    
14.         time.sleep(1.2)
    
15.         print "before release:recv_func(): " + str(id)
    
16.         self.lock.release()
    
17.          
    
18.     def send_func(self, id):
    
19.         print "before acquire:send_func(): " + str(id)
    
20.         self.lock.acquire()
    
21.         print "after acquire:send_func(): " + str(id)
    
22.         time.sleep(2)
    
23.         print "before release:send_func(): " + str(id)
    
24.         self.lock.release()
    
25.          
    
26.     def run(self):
    
27.         for i in range(5):
    
28.             self.recv_func(i)
    
29.             self.lock.acquire()
    
30.             print "after acquire:sock: run(): " + str(i)
    
31.             time.sleep(0.7)
    
32.             print "before release:sock: run(): " + str(i)
    
33.             self.lock.release()                       
    
34. 
    
35. def fileEntry():
    
36.     global sth
    
37.     for i in range(6):
    
38.         print "file: run(0): " + str(i)
    
39.         sth.send_func(i)
    
40.         print "file: run(1): " + str(i)
    
41.         time.sleep(1)
    
42.             
    
43. def main():
    
44.     global sth
    
45.     sth = sockThd()
    
46.     fth = threading.Thread(target=fileEntry, args=())
    
47.     sth.start()
    
48.     fth.start()
    
49.     sth.join()
    
50.     fth.join()
    
51.      
    
52.      
    
53. if __name__ == '__main__':
    
54.     main()

复制代码

Hadron74

运行了你的结果，问题在哪，请指出。

1. $ python thread.py
   
2. before acquire:recv_func(): 0
   
3. after acquire:recv_func(): 0
   
4. file: run(0): 0
   
5. before acquire:send_func(): 0
   
6. before release:recv_func(): 0
   
7. after acquire:sock: run(): 0
   
8. before release:sock: run(): 0
   
9. before acquire:recv_func(): 1
   
10. after acquire:recv_func(): 1
    
11. before release:recv_func(): 1
    
12. after acquire:sock: run(): 1
    
13. before release:sock: run(): 1
    
14. before acquire:recv_func(): 2
    
15. after acquire:recv_func(): 2
    
16. before release:recv_func(): 2
    
17. after acquire:sock: run(): 2
    
18. before release:sock: run(): 2
    
19. before acquire:recv_func(): 3
    
20. after acquire:recv_func(): 3
    
21. before release:recv_func(): 3
    
22. after acquire:sock: run(): 3
    
23. before release:sock: run(): 3
    
24. before acquire:recv_func(): 4
    
25. after acquire:recv_func(): 4
    
26. before release:recv_func(): 4
    
27. after acquire:sock: run(): 4
    
28. before release:sock: run(): 4
    
29. after acquire:send_func(): 0
    
30. before release:send_func(): 0
    
31. file: run(1): 0
    
32. file: run(0): 1
    
33. before acquire:send_func(): 1
    
34. after acquire:send_func(): 1
    
35. before release:send_func(): 1
    
36. file: run(1): 1
    
37. file: run(0): 2
    
38. before acquire:send_func(): 2
    
39. after acquire:send_func(): 2
    
40. before release:send_func(): 2
    
41. file: run(1): 2
    
42. file: run(0): 3
    
43. before acquire:send_func(): 3
    
44. after acquire:send_func(): 3
    
45. before release:send_func(): 3
    
46. file: run(1): 3
    
47. file: run(0): 4
    
48. before acquire:send_func(): 4
    
49. after acquire:send_func(): 4
    
50. before release:send_func(): 4
    
51. file: run(1): 4
    
52. file: run(0): 5
    
53. before acquire:send_func(): 5
    
54. after acquire:send_func(): 5
    
55. before release:send_func(): 5
    
56. file: run(1): 5
    

复制代码

ytmayer

回复 2# Hadron74

示例代码如下：  (估计要去掉sleep的代码/加大range范围才会跑出来)

示例代码不一定能跑出 两个线程同时acquire的状况

Hadron74

回复 3# ytmayer

我 试了 去除 sleep, 加到1600, 没有报错。