Ubuntu 20.04 LTS – Common Problem 014 – Diagnosis and Fix

📖 ~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

System becomes slow, OOM kills processes, and swap usage stays high under load.

Environment & Reproduction

Ubuntu 20.04 host with memory-intensive workloads, containers, or leak-prone services.

Root Cause Analysis

Insufficient RAM, runaway processes, aggressive caching, or poor service memory limits.

Quick Triage

Use ‘free -h’, ‘vmstat 1’, and ‘top/htop’ to identify pressure and top memory consumers.

Step-by-Step Diagnosis

Inspect OOM events in ‘journalctl -k’, profile process RSS over time, and check cgroup limits.

Solution – Primary Fix

Reduce memory usage, add swap or RAM, tune ‘vm.swappiness’, and restart leaking services.

Solution – Alternative Approaches

Set systemd MemoryMax for noisy services or horizontally scale workloads.

Verification & Acceptance Criteria

No OOM kills, acceptable latency, and swap in/out rates stabilize at low levels.

Rollback Plan

Restore prior sysctl settings and revert service limits if throughput drops unexpectedly.

Prevention & Hardening

Enable memory dashboards, alert on sustained swap growth, and load-test before releases.

Related Errors & Cross-Refs

Killed process by out-of-memory, cgroup memory limit exceeded, and kernel reclaim storms.

Related tutorial: View the step-by-step tutorial for Ubuntu 20.04 LTS.

View all Ubuntu 20.04 LTS tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

Ubuntu performance tuning docs, sysctl vm settings, and systemd resource control guide.