Set a JVM to dump heap when OutOfMemoryError is thrown

Question

I am trying to set the JVM of the server I am working on, so it dumps a heap to file when an OOME occurs.

I know I have to add this option -XX:-HeapDumpOnOutOf

Answer 1

This option from the HotSpot VM options. I would think it'd be the same in the OpenJDK VM but let me know if it's not.

-XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=<path to dump file>

You can also manually generate a memory map using jmap if you know the process id:

jmap -J-d64 -dump:format=b,file=<path to dump file> <jvm pid>

You can use JHat to analyze the dump.

jhat <path to dump file>

Answer 2

As mentioned by @CoolBeans, the JVM options to use are:

-XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=<path to dump file>

For setting this in tomcat, create a file named setenv.sh (setenv.bat for windows) under TOMCAT_HOME/bin directory & add the following line

export CATALINA_OPTS="$CATALINA_OPTS -XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=<path to dump file>"

CATALINA_OPTS is preferred for these kind of options as they need not be applied to the shutdown process.