Cache Stampede Chaos
Redis went down. Now every request is hammering your database.
The Scenario
Your Redis cache was restarted after a maintenance window. When it came back up, every single request hit the database simultaneously because the cache was empty. The database CPU spiked to 100%, queries are timing out, and the cache can't rebuild because the database is too slow to respond. You're in a thundering herd spiral.
What You'll Learn
Understanding the thundering herd / cache stampede problem
Using cache warming, staggered TTLs, and request coalescing
Diagnosing database overload from cache misses
Implementing circuit breakers and graceful degradation
Tools You'll Use
Real-World Context
The thundering herd problem has taken down Reddit, Facebook, and Wikipedia. It's a classic distributed systems failure that every caching layer must handle.
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