Latency cliffs every 90 seconds
A JVM service (G1GC, 32GB heap) develops periodic latency cliffs: every ~90 seconds, p99 jumps to 4-8s for a second or two, then recovers. GC logs show occasional 'Full GC (Allocation Failure)' events with pauses of 5+ seconds, alongside normal short young-gen pauses. Old-gen occupancy climbs steadily between Full GCs (sawtooth that doesn't fully reset). A deploy two days ago added an in-memory LRU-ish cache that holds rendered response fragments. Heap-used trend is slowly creeping up day over day. 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 40 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.