Ubuntu 20.04 LTS – swap exhaustion leads to OOM kills under peak load – 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

Kernel OOM kills critical processes during spikes, causing user-visible outages and job loss.

Environment & Reproduction

Occurs on memory-constrained hosts with bursty workloads and limited swap headroom.

Root Cause Analysis

Combined RAM and swap capacity cannot satisfy peak allocation, triggering OOM intervention.

Quick Triage

Identify killed processes and reduce load quickly to stabilize host behavior.

Step-by-Step Diagnosis

Analyze memory profile, swap usage trend, and cgroup limits for noisy workloads.

Solution – Primary Fix

Increase memory or swap appropriately and tune service limits plus vm.swappiness policy.

Solution – Alternative Approaches

Scale horizontally and split heavy jobs across nodes to reduce single-host pressure.

Verification & Acceptance Criteria

No new OOM kills under expected peak load and latency remains within SLO targets.

Rollback Plan

Revert kernel tunables and resource limits if performance regressions appear.

Prevention & Hardening

Add memory saturation alerts and pre-production stress testing for critical services.

Related Errors & Cross-Refs

Frequently coexists with swap thrashing, high iowait, and container eviction events.

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

Linux OOM behavior, Ubuntu memory tuning docs, and service resource governance guidance.