Ubuntu 18.04 LTS High CPU Usage from systemd-journald

📖 ~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

Persistent high CPU usage by journald degrades application performance and response times.

Environment & Reproduction

Observed on chatty Ubuntu 18.04 services emitting repeated errors without log throttling.

Root Cause Analysis

Unbounded log volume and bursty write patterns overwhelm journald processing.

Quick Triage

Identify top log producers and confirm whether spikes correlate with service errors.

Step-by-Step Diagnosis

Analyze journal rate, inspect noisy units, and review journald rate limit and storage settings.

Solution – Primary Fix

Fix noisy service behavior, tune journald rate limits, and restart affected services.

Solution – Alternative Approaches

Forward logs to external collectors and cap local retention aggressively.

Verification & Acceptance Criteria

CPU usage normalizes and journald throughput remains stable under expected load.

Rollback Plan

Revert journald config changes and restore prior logging path if side effects appear.

Prevention & Hardening

Set logging budgets per service and alert on abnormal journal write rates.

Related Errors & Cross-Refs

Linked issues include disk pressure from logs and service restart loops.

Related tutorial: View the step-by-step tutorial for Ubuntu 18.04 LTS.

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Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

Review systemd-journald documentation and Ubuntu performance troubleshooting guides.