Free mini course
One Expired Cache Key Is a Thundering Herd
The cache was supposed to protect the database. Instead it scheduled the outage. One popular key holds the product page, its TTL ends at a single instant, and two thousand in flight requests miss at exactly the same moment. Every one of them rebuilds the value itself.
This Short draws the stampede moving: the key expires, the herd misses together, two thousand identical queries land on Postgres in one second, the connection pool empties, and the page that was served from memory starts timing ou
Watch on YouTubeThe cache was supposed to protect the database. Instead it scheduled the outage. One popular key holds the product page, its TTL ends at a single instant, and two thousand in flight requests miss at exactly the same moment. Every one of them rebuilds the value itself.
This Short draws the stampede moving: the key expires, the herd misses together, two thousand identical queries land on Postgres in one second, the connection pool empties, and the page that was served from memory starts timing ou
Frequently asked questions
What is One Expired Cache Key Is a Thundering Herd about?
The cache was supposed to protect the database. Instead it scheduled the outage.
Which topics does this mini course relate to?
Caching, Go (Golang), System Design, Backend Development, Databases, Redis.