FreeBSD 14 – CPU Spikes from Runaway Process – Priority and Resource Containment

📖 ~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

One process saturates CPU, causing latency and degraded application performance.

Environment & Reproduction

Often linked to bad loops, stuck workers, or aggressive retries.

top -o cpu
ps -axo pid,ppid,pcpu,pmem,command | head

Root Cause Analysis

Application logic or scheduler pressure leads to runaway CPU consumption.

Quick Triage

Identify the offender quickly and reduce impact with temporary priority controls.

renice +10 -p 
cpuset -l 1 -p 

Step-by-Step Diagnosis

Trace process behavior, stack state, and syscall patterns.

procstat -kk 
truss -p  -o /tmp/.truss

Solution – Primary Fix

Patch or reconfigure offending service and restart controlled worker pools.

service  stop
# apply config fix
service  start

Solution – Alternative Approaches

Apply rctl limits to cap CPU impact while root-cause patch is prepared.

Verification & Acceptance Criteria

CPU utilization returns within baseline and queue latency normalizes.

top -SH
vmstat 1 5

Rollback Plan

Revert recent app deployment if CPU regression came from latest release.

Prevention & Hardening

Add watchdogs, timeouts, and resource quotas for high-risk worker services.

Related Errors & Cross-Refs

load average spikes, watchdog kill, worker timeout storms.

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 tuning and process control references.