Shawnna Brunk asked 1 year ago
Title : How to take heap dump on memory exception in weblogic?

Question :

How to take heap dump on memory exception in weblogic?

1 Answers
ParwezParwez Staff answered 1 year ago

Heap Dump provides snapshot of the Java process heap memory at a given time, it provides insight to troubleshoot memory leaks and other memory related issues.  Heap dumps are to memory what thread dumps are to java threads.

There are different ways to dump the java heap used by a Java application such as WebLogic Server.  Heap dumps can be triggered automatically by JVMs such as HotSpot or JRockit when an OutOfMemory event occurs.

Here are the most common ways to do it. You will use these if you have OutOfMemoryException (OOM) and you would like to take a look to the issue to determine the root cause.

1. For Hotspot/Oracle JDK, you need to add the following parameters to JAVA_OPTIONS

-XX:+HeapDumpOnOutOfMemoryError
-XX:HeapDumpPath=<path>

2. Similarly for JRockit, you need to the JAVA_OPTIONS below:

-XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=C:\myApp\hprof-dumps

But, lets say that you are experiencing OOM, but you still don’t determine the root cause of the issue.
You might probably need to restart as soon as you see performance issues or even better daily.
Then, #1 and #2 won’t help.

You can use a tool like the ones below:
3. Jmap, e.g.:

<JAVA_HOME>/bin/jmap -dump:format=b,file=c:\temp\heap.hprof <PID>

4. Or if you have already a core file and you would like to have a heap dump as well, you can also get a heap dump:

jmap  -dump:format=b,file=heap.hprof $JAVA_HOME/bin/java /home/lmestre/core.27436

5. Or even jrcmd for JRockit:
%JROCKIT_HOME%\bin\jrcmd <pid of target JVM> hprofdump filename=<full path name to the target dump file name>

To analyse the heap dump, you can use Eclipse MATor JMAP tools.

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