JVM warmup tail latency
A Java/JVM service runs behind a round-robin load balancer with rolling deploys, 40 instances. During and just after each rolling deploy, overall p99 latency spikes to 5-10x normal for a few minutes per instance, then settles — p50 is barely affected. Traces show the slow requests are landing on instances that were started seconds ago; the same endpoint on a long-running instance is fast. CPU on the fresh instances is briefly high. There's no error spike. How do you triage, and how do you stop fresh instances from poisoning the tail?
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 30 min
Which questions mattered is sealed until you submit. Telling you now would just be handing over the edge cases.
Run or narrate your approach, then ask the coach.