Concepts of redis cache avalanche, cache traversal, cache warm-up and cache hot backup

This article focuses on "redis cache avalanche, cache penetration, cache preheating and cache hot backup concepts", interested friends may wish to take a look. The method introduced in this paper is simple, fast and practical. Let's let the editor take you to learn the concepts of redis cache avalanche, cache penetration, cache preheating and cache hot backup.

Cache avalanche

When the cache is in a single point, once the cache server crashes, all requests will fall to the database tier. At this time, excessive visits will lead to database downtime, resulting in the unavailability of the entire website or service. This cache failure is commonly known as the cache avalanche.

Solution: to solve the cache avalanche failure, it is necessary to solve the single point problem, improve cache high availability, establish a distributed high availability cache system, one cache server fails, the other one gets up and continues to work, and it does not affect other cache systems.

Cache penetration

If the data corresponding to a key does not exist and the key is not cached, each request will be queried directly to the database through the cache. In the case of high concurrency, the database will go down directly, which is called cache penetration.

Solution: solve cache traversal. If you do cache, you should cache null values or empty lists, etc. If it is a malicious attack on a non-existent key, it is necessary to limit the frequency at the control layer.

Cache warm-up

The new cache system does not have any cached data, and the system performance and database load are not very good in the process of cache reconstruction, so it is best to load the hot data to be cached into the cache before the system goes online. This cache preloading method is cache preheating.

Cache hot standby

Cache hot backup means that when a cache server is not available, it can be switched to a backup cache server in real time without affecting the cache usage. In cluster mode, each master node has one or more slave nodes as a backup. Once the master node is hung up, the slave node immediately acts as the master node.

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