[java] How to analyze information from a Java core dump?

If a process crashes and leaves a core dump or I create one with gcore then how can I analyze it?

I'd like to be able to use jmap, jstack, jstat etc and also to see values of all variables.

This way I can find the reasons for a crashed or frozen JVM.

Maybe VisualVM can help (haven't yet had a chance to try it myself). Link:

http://java.sun.com/javase/6/docs/technotes/guides/visualvm/coredumps.html

See http://www.oracle.com/technetwork/java/javase/tsg-vm-149989.pdf. You can use "jdb" directly on the core file.

Actually, VisualVM can process application core dump.

Just invoke "File/Add VM Coredump" and will add a new application in the application explorer. You can then take thread dump or heap dump of that JVM.

Are you sure a core dump is what you want here? That will contain the raw guts of the running JVM, rather than java-level information. Perhaps a JVM heap dump is more what you need.

Try the lady4j stack analyzer, it could help you:

http://www.lady4j.com/solveStack.jsp

I recommend you to try Netbeans Profiler.It has rich set of tools for real time analysis. Tools from IbM are worth a try for offline analysis

jhat is one of the best i have used so far.To take a core dump,I think you better use jmap and jps instead of gcore(i haven't used it).Check the link to see how to use jhat. http://www.lshift.net/blog/2006/03/08/java-memory-profiling-with-jmap-and-jhat

IBM provide a number of tools which can be used on the sun jvm as well. Take a look at some of the projects on alphaworks, they provide a heap and thread dump analyzers

Karl

If you are using an IBM JVM, download the IBM Thread and Monitor Dump Analyzer. It is an excellent tool. It provides thread detail and can point out deadlocks, etc. The following blog post provides a nice overview on how to use it.

Okay if you've created the core dump with gcore or gdb then you'll need to convert it to something called a HPROF file. These can be used by VisualVM, Netbeans or Eclipse's Memory Analyzer Tool (formerly SAP Memory Analyzer). I'd recommend Eclipse MAT.

To convert the file use the commandline tool jmap.

# jmap -dump:format=b,file=dump.hprof /usr/bin/java core.1234

where:

dump.hprof is the name of the hprof file you wish to create

/usr/bin/java is the path to the version of the java binary that generated the core dump

core.1234 is your regular core file.