GC pauses after serialization refactor
A Go JSON API service shows latency jitter that started after a deploy: p50 is fine but p99 is sawtoothing and the service occasionally pauses. `runtime` metrics show GC running very frequently (many cycles per second) and `gc_pause_ns` is elevated; allocation rate (`go_memstats_alloc_bytes` rate) roughly tripled after the deploy. CPU usage also rose ~25% but the work done is the same. The deploy 'refactored a hot serialization path.' Heap size is stable — no leak. 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 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.