Python--day41--线程锁

1,死锁

死锁代码示例：

 import time
 from threading import Lock, Thread

 noodle_lock = Lock()
 fork_lock = Lock()

 def eat1(name):
     noodle_lock.acquire()
     print('%s拿到面了'%name)
     fork_lock.acquire()
     print('%s拿到叉子了'%name)
     print('%s吃面'%name)
     fork_lock.release()
     noodle_lock.release()

 def eat2(name):
     fork_lock.acquire()
     print('%s拿到叉子了' % name)
     time.sleep(1)
     noodle_lock.acquire()
     print('%s拿到面了'%name)
     print('%s吃面'%name)
     noodle_lock.release()
     fork_lock.release()

 Thread(target=eat1,args=('alex',)).start()
 Thread(target=eat2,args=('Egon',)).start()
 Thread(target=eat1,args=('bossjin',)).start()
 Thread(target=eat1,args=('nezha',)).start()

运行结果：

2,线程锁只能保证同一时间只有一个线程取n值，并不能保证数据安全

3,加锁保证了n不会被多个线程操纵；加锁保证数据安全

 import time
 from threading import Lock,Thread

 def func(lock):
     global n
     #加锁保证了n不会被多个线程操纵
     #获取锁的钥匙，加锁
     lock.acquire()
     temp = n
     time.sleep(0.2)#睡眠0.2s
     n = temp -1
     #释放锁
     lock.release()

 n = 10
 t_lst = []
 lock = Lock()
 for i in range(10):
     t = Thread(target=func,args=(lock,))
     t.start()
     t_lst.append(t)

 for t in t_lst:t.join()
 print(n)

运行结果：