【10.4】线程同步--Lock、RLock

概述1 #!/user/bin/env python 2 # -*- coding:utf-8 -*- 3 4 import dis 5 import threading 6 from threading import Lock 7 total = 0 8 lock = Lock() 9 10 11 def add():12 global tota

 1 #!/user/bin/env python 2 # -*- Coding:utf-8 -*- 3  4 import dis 5 import threading 6 from threading import Lock 7 total = 0 8 lock = Lock() 9 10 11 def add():12     global total13     global lock14     for i in range(1000000):15         # 获取锁16         lock.acquire()17         total += 118         # 释放锁19         lock.release()20 21 22 def desc():23     global total24     global lock25     for i in range(1000000):26         # 获取锁27         lock.acquire()28         total -= 129         # 释放锁30         lock.release()31 32 33 thread1 = threading.Thread(target=add)34 thread2 = threading.Thread(target=desc)35 36 thread1.start()37 thread2.start()38 39 40 def add1(a):41     a += 142 43 44 def desc1(a):45     a -= 146 47 48 """49 1.load a50 2.load 151 3.+(-)52 4.赋值给a53 """54 print(dis.dis(add1))55 print(dis.dis(desc1))56 57 thread1.join()58 thread2.join()59 60 print(total)

 41           0 LOAD_FAST                0 (a)              2 LOAD_CONST               1 (1)              4 INPLACE_ADD              6 STORE_FAST               0 (a)              8 LOAD_CONST               0 (None)             10 RETURN_VALUENone 45           0 LOAD_FAST                0 (a)              2 LOAD_CONST               1 (1)              4 INPLACE_SUBTRACT              6 STORE_FAST               0 (a)              8 LOAD_CONST               0 (None)             10 RETURN_VALUENoneC:\Users\administrator\Python\imooc>python demo.py 41           0 LOAD_FAST                0 (a)              2 LOAD_CONST               1 (1)              4 INPLACE_ADD              6 STORE_FAST               0 (a)              8 LOAD_CONST               0 (None)             10 RETURN_VALUENone 45           0 LOAD_FAST                0 (a)              2 LOAD_CONST               1 (1)              4 INPLACE_SUBTRACT              6 STORE_FAST               0 (a)              8 LOAD_CONST               0 (None)             10 RETURN_VALUENone0C:\Users\administrator\Python\imooc>python demo.py 41           0 LOAD_FAST                0 (a)              2 LOAD_CONST               1 (1)              4 INPLACE_ADD              6 STORE_FAST               0 (a)              8 LOAD_CONST               0 (None)             10 RETURN_VALUENone 45           0 LOAD_FAST                0 (a)              2 LOAD_CONST               1 (1)              4 INPLACE_SUBTRACT              6 STORE_FAST               0 (a)              8 LOAD_CONST               0 (None)             10 RETURN_VALUENone0

 

1.用锁会影响性能

2.锁会引起死锁

 

RLock

 1 #!/user/bin/env python 2 # -*- Coding:utf-8 -*- 3  4 import threading 5 # RLock，在同一个线程里面，可以连续调用多次acquire，一定要注意acquire的次数要和release的次数相等 6 # 线程间还是有相互竞争的关系 7 from threading import RLock 8 total = 0 9 lock = RLock()10 11 12 def add():13     global total14     global lock15     for i in range(1000000):16         # 获取锁17         lock.acquire()18         lock.acquire()19         total += 120         # 释放锁21         lock.release()22         lock.release()23 24 25 def desc():26     global total27     global lock28     for i in range(1000000):29         # 获取锁30         lock.acquire()31         total -= 132         # 释放锁33         lock.release()34 35 36 thread1 = threading.Thread(target=add)37 thread2 = threading.Thread(target=desc)38 39 thread1.start()40 thread2.start()41 42 thread1.join()43 thread2.join()44 45 print(total)

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