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：