How to Diagnose a 100% CPU Spike in 3 Minutes: From Symptom to Root Cause
When a production service shows 100% CPU usage, this guide walks you through a rapid three‑minute workflow—identifying the affected scope, distinguishing user, system, iowait, steal and softirq metrics, and using Linux, systemd, Docker/Kubernetes and language‑specific tools to pinpoint the offending process, thread, or system call before taking corrective actions such as throttling, scaling, or rolling back.
