FreeBSD 14 – sustained high CPU from runaway worker process loop – Fix & Prevention

📖 ~1 min read

Table of contents

1. Symptom & Impact
2. Environment & Reproduction
3. Root Cause Analysis
4. Quick Triage
5. Step-by-Step Diagnosis
6. Solution – Primary Fix
7. Solution – Alternative Approaches
8. Verification & Acceptance Criteria
9. Rollback Plan
10. Prevention & Hardening
11. Related Errors & Cross-Refs
12. References & Further Reading

Symptom & Impact

Compute saturation increases latency, destabilizes co-hosted services, and misses SLAs.

Environment & Reproduction

Common after concurrency changes that remove queue blocking or retry backoff.

Root Cause Analysis

Busy loops continuously consume CPU due to unbounded retries and poor pacing logic.

Quick Triage

Capture stack traces and performance counters before restart to preserve evidence.

Step-by-Step Diagnosis

Profile hot paths, inspect retry metrics, and validate worker pool settings.

Solution – Primary Fix

Introduce bounded retries, exponential backoff, and capped worker concurrency.

Solution – Alternative Approaches

Apply process CPU limits and isolate noisy workloads in dedicated jails.

Verification & Acceptance Criteria

CPU utilization returns to baseline and latency stabilizes under expected load.

Rollback Plan

Redeploy prior stable release if new controls reduce throughput unexpectedly.

Prevention & Hardening

Require load-test validation for any worker-loop or retry-policy changes.

Related Errors & Cross-Refs

Related to queue growth, memory pressure, and timeout cascades.

Related tutorial: View the step-by-step tutorial for FreeBSD 14.

View all FreeBSD 14 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

FreeBSD performance diagnostics and service capacity planning references.