在Redis中，如果設置的maxmemory，那就要配置key的回收機制參數maxmemory-policy，默認volatile-lru，參閱Redis作者的原博客：antirez weblog >> Redis as an LRU cache
原文中寫得很清楚：
復制代碼 代碼如下:
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.
# 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
