Cache Warming

Caching works well when the data users need is already close to the application.

The risky moment is the first few minutes after a deploy, cache restart, large scale-out event, or large cache delete. The application may be healthy, but the cache does not yet contain the data needed for normal traffic. Requests that usually return from memory now fall through to the database or another service.

That is the cold cache problem.

Cache warming reduces this risk by loading important data into the cache before full production traffic depends on it.

This chapter covers what cache warming means, why cold caches cause incidents, when warming is worth the extra work, common warming strategies, how to choose what to warm, and the production practices that keep warming safe.