Message retry storm collapses throughput
At 10:40 your SQS-backed worker fleet's processing throughput collapses and the queue depth explodes to millions. Dashboards: a single message type started failing at 10:35; the consumers retry failed messages, and because visibility-timeout redelivery + your app-level retry both fire, the same messages cycle endlessly; CPU on workers is high but 'useful work done' (successful completions) is near zero; the DLQ is empty (maxReceiveCount is set very high). A schema change shipped at 10:34. 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 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.