用上面代码实现锁的自动续期

实现锁的自动续期需要在获取锁的时候开启一个续期线程，定时更新锁的过期时间。具体实现如下：

import time
import threading

class Lock(object):
    def __init__(self):
        self.locked = False
        self.locker = None
        self.expire_time = None
        self.auto_renew_thread = None
    
    def acquire(self, locker, expire_time):
        while self.locked:
            time.sleep(0.1)
        self.locked = True
        self.locker = locker
        self.expire_time = expire_time
        self.auto_renew_thread = threading.Thread(target=self.auto_renew)
        self.auto_renew_thread.start()
    
    def release(self, locker):
        if self.locker == locker:
            self.locked = False
            self.locker = None
            self.expire_time = None
            self.auto_renew_thread.join()
    
    def auto_renew(self):
        while self.locked:
            # 续期时间为锁过期时间的一半
            renew_time = (self.expire_time - time.time()) / 2
            time.sleep(renew_time)
            self.expire_time = time.time() + expire_time

# 测试
lock = Lock()
locker = 'test'
expire_time = 10
lock.acquire(locker, time.time() + expire_time)
print('Lock acquired')
time.sleep(5)
print('Lock still held')
lock.release(locker)
print('Lock released')

在获取锁时，开启一个自动续期的线程。该线程定期更新锁的过期时间。在释放锁时，停止自动续期线程。这样可以保证锁在被持有期间一直有效。