Caching Strategies Simulator — Interactive System Design Lab
Expire a hot cache key and watch every concurrent in-flight request miss at the same instant and hit the database together — a thundering herd. Compare a per-key lock (one request recomputes, the rest wait) against serving the stale value while a background job revalidates. Then look at the case that actually takes systems down: a cache warmed at deploy time where thousands of keys share one TTL, and see TTL jitter spread the expiries and flatten the spike. LRU (Least Recently Used) eviction — the pattern behind Redis and Memcached — is also here as a second scenario.
Expire a hot key and watch every in-flight request stampede the database at once — then fix it with a lock, stale-while-revalidate, and TTL jitter.
This free interactive simulation runs directly in your browser — no account needed. Adjust the parameters and watch how the system responds in real time.
Concepts covered
- cache stampede
- thundering herd
- TTL jitter
- caching
- LRU
- cache eviction
- cache hit rate
- Redis
- Memcached
- least recently used
Read the guide
- Caching — The single most effective way to scale a system. Learn the patterns (Write-Through vs Write-Back), the Eviction policies, and the dangers of the Thundering Herd.
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