Using HeapDumpOnOutOfMemoryError parameter for heap dump for JBoss

java

heap-dump

memory-leaks

jvm-configuration

byAlex Kataev·Oct 4, 2024

To create a heap dump for your JBoss server on an OutOfMemoryError, combine the parameters -XX:+HeapDumpOnOutOfMemoryError and -XX:HeapDumpPath=/your/dump/path in JAVA_OPTS.

Here's an example:

# Adding memory: Expert mode, proceed with caution!
# Don't worry, no programmers were harmed in the making of this heap dump
JAVA_OPTS="$JAVA_OPTS -XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=/your/dump/path"

Configure your dump path, give JBoss a quick restart, and voila! On the event of memory troubles, there'll be a shiny new dump file. It's like a treasure chest full of heap insights!

Heap Dump Location and Format

The default location for the glorious heap dump file is the working directory of the JVM (typically, JBOSS_HOME/bin). But if you're like me and appreciate a well-organized system, direct the dump to a custom location like /disk2/dumps using -XX:HeapDumpPath=. Just make sure this path is write-accessible and roomy enough for your potential heap dump.

By default, you'll find your heap dump file named as java_pid.hprof (pid being the process identifier). This is the normal naming convention for Oracle/OpenJDK. However, this name might differ based on the JVM. For instance, the IBM JDK will create a phd file format (likely found chillin' in the /tmp directory).

Proactive Monitoring and Space Management

Before you're ambushed by an OutOfMemoryError, take these proactive steps:

Conduct regular heap dump analysis in a mock-up environment to catch memory leaks before they sneak up on you.
Enable alerts via monitoring tools to preemptively warn you when memory usage is looking flaky.
Implement auto-archiving of old dumps. Nobody likes an overflowing disk, am I right?

Nifty Analysis Techniques

Surpass the basics of heap dump utilization by exploring these advanced techniques:

Use heap dump analysis tools like Eclipse Memory Analyzer or JVisualVM. They're fantastic for spying on object retention and potential memory leaks.
Compare heap dumps from different instances to identify trends or single out momentary leaks.
Create custom scripts to sort through hprof files. They're efficient at extracting relevant data and automating part of the analysis.
Invest in a continuous monitoring solution that compares heap dumps with companion metrics.

Extra Configurations and Setup

Heap dumps aren't just about taking them - you've got to manage and understand 'em too:

Remember to fine-tune the heap dump format based on your platform.
Max out on heap dumps? Implement a log rotation or cleanup policy.
Consider advanced JVM arguments like -XX:+PrintGCDetails and -XX:+PrintGCTimeStamps for a more complete memory usage understanding.