Latency
3 engineering logs on Latency. Newest first.
- Your p99 is a garbage collector setting
Why a tail latency that no profiler explains is usually a stop the world pause, why allocation rate matters more than heap size, and why a bigger heap can make the tail worse.
- Why your Redis is slow: it is single threaded and you sent it KEYS
Why one O(N) command blocks every other client on the server, which everyday commands are secretly linear, and why a p99 spike with flat CPU is almost always somebody scanning the keyspace.
- Your ORM issued 400 queries and the p99 looked fine until it didn't
Why N+1 queries are invisible to every database side metric you own, how a getter call becomes a network round trip, and why the fix that looks obvious produces a cartesian product.