hard20 pts · first answer countscachingredisperformance

Cache expiry takes down the database

The homepage feed is cached in Redis for 60 seconds. Each time the key expires, thousands of requests miss at once and all run the same heavy query, spiking the database. What is the best fix?

A.Let one request rebuild the value (lock or single-flight) while others get the stale copy, and add jitter to TTLsB.Lower the TTL to 5 seconds so values are always freshC.Remove the cache and add read replicasD.Cache the value in each user’s browser instead

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