Ubuntu 20.04 LTS – OOM killer terminates critical processes

📖 ~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

Critical applications are killed unexpectedly, causing downtime and data loss risk.

Environment & Reproduction

Appears under sudden memory spikes, leaks, or insufficient swap allocation.

Root Cause Analysis

Kernel out-of-memory logic selects processes when reclaim cannot recover enough RAM.

Quick Triage

Confirm OOM events in kernel logs and identify terminated processes.

Step-by-Step Diagnosis

Analyze memory timeline, cgroup limits, and process-level growth patterns.

Solution – Primary Fix

Increase memory headroom, tune limits, and fix application memory leaks.

Solution – Alternative Approaches

Set oom_score_adj and cgroup protections for critical services.

Verification & Acceptance Criteria

No new OOM kills occur under peak workload tests.

Rollback Plan

Revert memory policy changes if they introduce resource starvation elsewhere.

Prevention & Hardening

Deploy memory SLO alerts and load-shedding controls before saturation.

Related Errors & Cross-Refs

Out of memory: Kill process, oom_reaper, and memory cgroup out of memory.

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, cgroup memory controls, and Ubuntu tuning guidance.