Dumping Java Heap File on OutOfMemoryError using Jmap

Question

I've been trying to dump the heap file when an OutOfMemoryError occurs on a given Java process using Jmap.

I have been able to dump the heap file but I want to add the HeapDumpOnOutOfMemoryError flag to Jmap but I think I'm doing something wrong. Am I doing something wrong? I've tried:

jmap -J-XX:+HeapDumpOnOutOfMemoryError -dump:live,file=/home/eduardo2/dumpfile.hprof 18763

When I run the above it just says the following -- but it doesn't wait for the OutOfMemoryError:

>> Dumping heap to /home/eduardo2/dump21file.hprof ...
>> Heap dump file created

Answer 1

You are mixing up two different things:

• Use jmap to capture a heap dump from a running process like you did. See https://docs.oracle.com/javase/7/docs/technotes/tools/share/jmap.html.
• Use -XX:+HeapDumpOnOutOfMemoryError on the java process you are expecting to throw the OOM. If the exception occurs, a dump will be written to the current directory. See https://docs.oracle.com/javase/7/docs/webnotes/tsg/TSG-VM/html/clopts.html#gbzrr