On-callMediumoc-g543

Subject Slow dependencyLevel Entry–Mid~20 minCommon in Code quality & review interviewsIndustries Software development, Technology

Question

Your service's latency dashboard shows requests getting slow and some returning 504 Gateway Timeout. Drilling in, the slowness is concentrated on endpoints that call one downstream service; endpoints that don't call it are fast. The downstream's own status page shows it's degraded. You didn't deploy. Your service's threads/connections are filling up waiting on it. How do you triage and protect your service?

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.

Learn the concepts

Diagram & narrate the incident

Loading whiteboard…

Run or narrate your approach, then ask the coach.