عرض عملي: اندفاع بعد انتهاء صلاحية الذاكرة المؤقتة ثم الإصلاح

خطوة بخطوة

1. Cache product:7 with a 10 s TTL; run a load test of 200 concurrent readers.
2. Count database queries at expiry: a spike to about 200 identical queries.
3. Fix 1: a per-key lock (one loader; the rest wait or serve the stale value) or Caffeine LoadingCache; show 1 query.
4. Fix 2: add random jitter of ±20% to TTLs and early refresh.
5. Planned mistake: the lock has no timeout and the loader fails; every request waits forever. Fix: lock timeout, and on timeout serve the stale value or fail fast.
6. Show the database query count as a flat line during expiry.

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