Cianplan

Level 2: Data · L2.6 Caching strategies

Stampedes, hot keys and eviction

Prevent thundering herds and handle hot keys; pick LRU vs LFU.

13 min · Pro

What you take away

  • When a hot key expires, every concurrent request misses at once and they all hit the database together.

And 3 more inside the class, in Pro.

How the class is laid out

  1. The problem
  2. The simple version
  3. Four fixes for the herd
  4. Hot keys, and what to evict
  5. Check your understanding