Check a Cache for Staleness Bugs
Added 2026-11-03
Caching is not just TTL; it is also read-after-write and invalidation order.
Here is a cache design or code. Check: 1) whether TTL matches how often the data changes; 2) whether read-after-write can return the old value; 3) invalidation versus update ordering and the intermediate state; 4) consistency across multiple instances; 5) a minimal protection against cache stampede; 6) the staleness risk most easily missed.
Site original
Chinese original
How to use
缓存 bug 的典型形状：数据已经改了，用户还看到旧的。
Try tweaking it
- Have it restate requirements and constraints before writing code.
- Ask for the smallest change plus a rollback path, not a full-file rewrite.
What you should get
- A minimal, runnable change with copy-ready code
- Impact list: which files and call sites must follow
Common mistakes
- Asking it to touch ten files at once, then losing track of what broke what.
- Pasting only the error, with no code or version, and getting an unfixable answer.
How to check the output
- The change runs, can be rolled back, and touches nothing unrelated.
- Edge cases (empty, oversized, concurrent) are covered or explained.
Where it works
- Good for: having it restate requirements and constraints, then propose the smallest runnable change.
- Watch out: include versions and a minimal reproduction with the error, or the fix may look plausible but not fit.