Where to find the heap dump after an "Out Of Memory"

Question

I'm using ASANT to run a xml file which points to a NARS.jar file.

I'm getting "java.lang.OutOfMemoryError: Java heap space" and i'm researching around this.

So i have found that i need to set "-XX:+HeapDumpOnOutOfMemoryError", to create a dump file to analyze.

I edited ASANT.bat and added the "-XX:+HeapDumpOnOutOfMemoryError" to ANT_OPTS:

set ANT_OPTS= "-XX:+HeapDumpOnOutOfMemoryError" "-Dos.name=Windows_NT" "-Djava.library.path=%AS_INSTALL%\lib;%AS_ICU_LIB%;%AS_NSS%" "-Dcom.sun.aas.installRoot=%AS_INSTALL%" "-Dcom.sun.aas.instanceRoot=%AS_INSTALL%" "-Dcom.sun.aas.instanceName=server" "-Dcom.sun.aas.configRoot=%AS_CONFIG%" "-Dcom.sun.aas.processLauncher=SE" "-Dderby.root=%AS_DERBY_INSTALL%"  

But i can't seem to find any dump file. I will use the Eclipse Memory Analyzer to analyze when i find the dump.

I also tried to set the option "-XX:HeapDumpPath=c:\memdump\bds.hprof", but no dump was created there.

Anyone got an idea of what i'm doing wrong? Thanks in advance

Answer 1

It looks like your application is running on Windows. A Windows file path needs to be escaped with \. As per your example, -XX:HeapDumpPath should look like:

-XX:HeapDumpPath=c:\\memdump\\bds.hprof

Besides ‘-XX:+HeapDumpOnOutOfMemoryError’ there are several other options to capture heap dumps as well.

Answer 2

I found that i could use VisualVM from SUN to get a heapdump, and see it live.

Easy solution

Answer 3

It's in the working directory of the application (i.e. where you've started it). I'm not sure what happens if the process does not have the necessary privileges to do so. Probably, writing the dump would fail silently.