Backend & systems·Caching and invalidation
the popular key expired and ten thousand requests all missed at the same instant and went straight through to the database.
Cache stampede
Also calledthundering herd, dogpile, cache miss storm
When a hot entry expires or is evicted, every concurrent request for it misses and recomputes it at once, and the load the cache was absorbing arrives at the origin in a single spike. The database being fine at steady state tells you nothing about whether it survives this. The fixes are a lock or single-flight around the recompute, early probabilistic refresh, or serving stale while one request refreshes.