Redis single core saturated
Every service that touches the shared Redis suddenly sees latency spike together at 11:20 — sessions, rate-limiting, and feature flags all slow at once. Redis dashboards: the single Redis primary's CPU is pinned at 100% on one core (the box has spare cores), `instantaneous_ops_per_sec` is flat (not rising) while the slowlog fills up, and clients pile up in the connected-clients count. A new analytics feature deployed at 11:15 runs periodic `KEYS pattern:*` and large `SMEMBERS` calls against the same instance. 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 35 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.