intermediate · resources

CPU Is at 100%

CPU on your service is pegged at 100%. What do you investigate?

Practical scenario

A checkout service is at 97–100% CPU across all 12 instances. Latency p99 has roughly doubled. Traffic is within 5% of last week.

What it tests

  • Whether the candidate checks that CPU is actually the constraint
  • Knowledge of profiling as the tool for this question
  • Awareness that the runtime, not the application, is often the consumer

Lessons behind this question