الاندفاعات (Stampedes)

في هذا الدرس

explain a cache stampede and the three standard defences.

الموضوعات المخطط لها

• A stampede: a hot key expires and many requests miss at once, all hitting the database for the same row.
• Locking: only one request rebuilds; the others wait or serve the old value.
• Request coalescing (single flight): concurrent loads of one key share one call (Caffeine LoadingCache does this per instance).
• Early refresh: refresh before expiry (refreshAfterWrite) or add random jitter to TTLs.
• Per-instance coalescing still allows one load per instance; use a distributed lock for stronger protection.