如何利用redis实现倒计时任务

import redis
import time

def event_handler(msg):  
    '''
    监听到任何key过期后，得到的消息如下
    msg ={'type': 'pmessage', #返回值类型
    'pattern': '__keyevent@2__:expired', #来源
     'channel': '__keyevent@2__:expired', # 实际的Channel
      'data': 'mykey' # key名称
      }
    可以根据您要监控的key进行业务判断或触发其他事件
    if msg['data']=='mykey':
        do....
    elif msg['data']=='yourkey':
        do ----
    '''
    print(msg)
 
    
redis_conn = redis.Redis(host='host', port='6379', db=2, password='test.123.com', decode_responses=True)
#设置过期时间2秒
redis_conn.set('mykey', 'asjdhkjashdkjahdskjahsd', ex=2)
# 订阅消息
pubsub =redis_conn.pubsub()
# 订阅key过期事件
# __keyevent@2__:expired ： __keyevent@{db}__:事件
pubsub.psubscribe(**{'__keyevent@2__:expired': event_handler})
while True:  
    message = pubsub.get_message()
    if message:
        # redis_conn.set('mykey', 'asjdhkjashdkjahdskjahsd', ex=10)
        print('wqwqwqwqwqwqwqwqwqwqwqwqwqwqwqwqwqwq')
    else:
        time.sleep(0.01)