Paths/Backend Engineer/Caching & Performance / Cache Strategies
Defend Against a Cache Stampede
When a hot key expires, a thousand requests hit the database at once. Write the defence - a single flight, a short lock and a little jitter.
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01Requirements
live checks- File ~/backend/cache/stampede.md exists○
- The document describes the single flight pattern○
- The document states how the lock is released○
- The document explains the role of jitter○
02Walkthrough
1 of 4 revealed- 01
Describe the stampede
Start with the failure - a popular key expires and the whole fleet hits the database at the same instant.
echo '# Cache stampede\n\n## The failure\n\nA popular key expires and every request misses at the same moment, so the database sees a thundering herd.' > ~/backend/cache/stampede.md - 3 locked · each failed submit reveals one
03Stuck?
0 of 3 revealedTake a hint without losing the lab — each one points at the thing to look at, not at the answer.
04AI Tutor
guides, never solvesTell me what you're stuck on — I'll nudge, not solve. Which requirement are you looking at?
04Notebook
saved locally in this browserlearner@lab — ubuntu:24.04
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