How to deal with full memory of redis

When Redis memory reaches its upper limit, it takes the following steps: Evict key-value pairs using an eviction strategy such as LRU, TTL, or Random Selection. Select the key-value pair to be evicted based on the key size, expiration time, and access frequency. Recycle memory space occupied by the evicted key-value pair. If the eviction still fails to free up sufficient memory, stop the client connection or reject new writes. Monitor memory usage and adjust eviction policy and memory size settings as needed.

Redis Memory Management

How to deal with Redis full memory?

When the memory space of the Redis server reaches its upper limit, it takes the following steps:

1. Evicting Strategy

Redis uses a variety of eviction strategies to decide which key-value pairs to evict:

• volatile-lru: Eviction of the least recently used key-value pairs (only for keys with TTL (time of survival)).
• volatile-random: Randomly expel key-value pairs with TTL.
• volatile-ttl: Evide the smallest key-value pair of TTL.
• allkeys-lru: Evide all key-value pairs that are least used recently (including keys without TTL).
• allkeys-random: Randomly expels all key-value pairs.
• no-eviction: does not expel any key-value pairs, but causes new writes to fail.

2. Key-value pair selection

After determining the eviction strategy, Redis selects the key-value pair to be evict based on the following conditions:

• Key size: Smaller keys are usually expelled first.
• Expiration time of keys: Keys with shorter TTLs are expelled first.
• Key access frequency: Keys with lower frequency are expelled first.

3. Memory recovery

When key-value pairs are evicted, Redis reclaims the memory space it takes to make room for new data.

4. Handling when memory is insufficient

If the eviction policy still fails to free up enough memory space, Redis will trigger the following measures:

• Terminate client connection: Redis will disconnect the new client connection, preventing the server from crashing due to insufficient memory.
• Reject new writes: Redis will block new write operations until memory space is freed.

5. Monitoring and Adjustment

To avoid memory shortage, it is recommended to monitor Redis's memory usage and adjust the eviction policy and memory size settings as needed.

The above is the detailed content of How to deal with full memory of redis. For more information, please follow other related articles on the PHP Chinese website!