Code RoomGarbage collection pauses degrade
HardPrep Room Coding #2679

Garbage collection pauses degrade

On-callReliability & on-callSenior–Staff~28 min

Your JVM search service degrades under a gradual traffic increase: p99 climbs and a few instances become briefly unresponsive, then recover, in a rolling pattern. CPU shows frequent spikes to 100% but the request rate that triggers it is only ~20% above last month. GC logs show full GCs every few seconds with multi-hundred-millisecond pauses, heap usage sawtoothing near the max, and old-gen filling faster than it's collected. A recent change added a large per-request in-memory result cache. How do you triage and mitigate?

What a strong answer looks like

Stop the bleeding first (mitigate), then form hypotheses from real signals. Separate root cause from symptom, communicate status as you go, and close with what prevents a repeat.

0:00 of about 28 min
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