欢迎您访问程序员文章站本站旨在为大家提供分享程序员计算机编程知识!
您现在的位置是: 首页  >  IT编程

Redis的LRU机制介绍

程序员文章站 2022-06-24 22:36:52
在redis中,如果设置的maxmemory,那就要配置key的回收机制参数maxmemory-policy,默认volatile-lru,参阅redis作者的原博客:an...

在redis中,如果设置的maxmemory,那就要配置key的回收机制参数maxmemory-policy,默认volatile-lru,参阅redis作者的原博客:antirez weblog >> redis as an lru cache

原文中写得很清楚:

复制代码 代码如下:

another way to use redis as a cache is the maxmemory directive, a feature that allows specifying a maximum amount of memory to use. when new data is added to the server, and the memory limit was already reached, the server will remove some old data deleting a volatile key, that is, a key with an expire (a timeout) set, even if the key is still far from expiring automatically.

在redis服务器占用内存达到maxmemory的情况下,当再想增加内存占用时,会按maxmemory-policy机制将老的数据删除。这里简单说一下volatile-lru,redis会按lru算法删除设置了过期时间但还没有过期的key,而对于没有设置过期时间的key,redis是永远保留的。当然,如果你不想删除没有过期的key,那可以使用noeviction机制
复制代码 代码如下:

# maxmemory policy: how redis will select what to remove when maxmemory
# is reached? you can select among five behavior:
#
# volatile-lru -> remove the key with an expire set using an lru algorithm
# allkeys-lru -> remove any key accordingly to the lru algorithm
# volatile-random -> remove a random key with an expire set
# allkeys-random -> remove a random key, any key
# volatile-ttl -> remove the key with the nearest expire time (minor ttl)
# noeviction -> don't expire at all, just return an error on write operations