请解释什么是线程锁，以及如何使用线程锁

• 线程锁: 目的是将一段代码锁住，一旦获得锁权限，除非释放线程锁，否则其他任何代码都无法获得锁权限
• 为什么需要线程锁
  • 多线程同时在完成特定的操作时，由于并不是原子操作，所以在完成操作的过程中可能会被打断，去做其他的操作
  • 可能产生脏数据
  • 例如，一个线程读取变量n 【初始值是0】，然后n++, 最后输出n，当访问n++后，被打断，由另外的线程做同样的工作，这时n被加了2次，所以n最后等于2，而不是1

from atexit import register
from threading import Thread, Lock, currentThread
from time import sleep, ctime
import random

lock = Lock()
print(type(lock))

def fun(): lock.acquire()  # 加锁 for i in range(5): print('Thread Name', '=', currentThread().name, 'i', '=', i) sleep(random.randint(1, 5)) lock.release()  # 释放锁 def main(): for i in range(3): Thread(target=fun).start() @register
def exit(): print('线程执行完毕: ', ctime()) main()

  

 

  
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<class '_thread.lock'>
Thread Name = Thread-13 i = 0
Thread Name = Thread-13 i = 1
Thread Name = Thread-13 i = 2
Thread Name = Thread-13 i = 3
Thread Name = Thread-13 i = 4
Thread Name = Thread-14 i = 0
Thread Name = Thread-14 i = 1
Thread Name = Thread-14 i = 2
Thread Name = Thread-14 i = 3
Thread Name = Thread-14 i = 4
Thread Name = Thread-15 i = 0
Thread Name = Thread-15 i = 1
Thread Name = Thread-15 i = 2
Thread Name = Thread-15 i = 3
Thread Name = Thread-15 i = 4

  

 

  
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from atexit import register
from threading import Thread, Lock, currentThread
from time import sleep, ctime
import random

lock = Lock()
print(type(lock))

def fun(): # lock.acquire()  # 加锁 for i in range(5): print('Thread Name', '=', currentThread().name, 'i', '=', i) sleep(random.randint(1, 5)) # lock.release()  # 释放锁 def main(): for i in range(3): Thread(target=fun).start() @register
def exit(): print('线程执行完毕: ', ctime()) main()

  

 

  
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<class '_thread.lock'>
Thread Name = Thread-16 i = 0
Thread Name = Thread-17 i = 0
Thread Name = Thread-18 i = 0
Thread Name = Thread-16 i = 1
Thread Name = Thread-17 i = 1
Thread Name = Thread-18 i = 1
Thread Name = Thread-17 i = 2
Thread Name = Thread-16 i = 2
Thread Name = Thread-17 i = 3
Thread Name = Thread-18 i = 2
Thread Name = Thread-18 i = 3
Thread Name = Thread-18 i = 4
Thread Name = Thread-17 i = 4
Thread Name = Thread-16 i = 3
Thread Name = Thread-16 i = 4

  

 

  
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66 - 请解释什么是信号量，以及如何使用信号量

文章来源: ruochen.blog.csdn.net，作者：若尘，版权归原作者所有，如需转载，请联系作者。

原文链接：ruochen.blog.csdn.net/article/details/104851649