IBM AIX 7.2 – Common Problem 025 – 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

Java process generates javacore/heapdump and exits with OutOfMemoryError.

Environment & Reproduction

IBM AIX 7.2 LPAR exhibiting WebSphere/Java JVM core dump issues under standard PowerVM workloads.

ulimit -a
java -version

Root Cause Analysis

Default ulimit data/stack settings or 32-bit JVM limits cause OOM.

Quick Triage

Confirm scope with errpt, recent changes, and subsystem state via lssrc.

errpt | grep -i CORE
ls -lt /tmp/*.dmp

Step-by-Step Diagnosis

Inspect javacore, GC log, and ulimit profile.

/usr/java8_64/bin/jstack 
cat /tmp/javacore.*.txt | head

Solution – Primary Fix

Raise ulimits and tune JVM heap; rerun with verbose GC.

ulimit -d unlimited
java -Xmx4g -Xms2g -verbose:gc -jar app.jar

Solution – Alternative Approaches

Switch to 64-bit IBM Semeru JDK and enable compressed refs.

Verification & Acceptance Criteria

Confirm subsystem returns to RUNNING state and errpt shows no new entries.

ps -o pid,vsz,rss -p 
cat /tmp/javacore.txt | head

Rollback Plan

Restore prior configuration from mksysb or alt_disk_install clone if the fix regresses.

ulimit -d 524288  # revert if app fault returns

Prevention & Hardening

Encode the fix in NIM customisation scripts and monitor via topas/nmon.

smit chgsys  # set default ulimits in /etc/security/limits

Related Errors & Cross-Refs

Core dumps under /tmp; OOM Killer activity

Related tutorial: View the step-by-step tutorial for aix-7.2.

View all aix-7.2 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

IBM Semeru / Java SDK on AIX