If you have a JVM system heapdump on WebSphere, before you can use the excellent tools provided in IBM Support Assistant, you’ll need to use the jextract command to pre-process the dump file. I’ve recently been doing this on 64bit WebSphere Application Server 188.8.131.52 on AIX, and I wanted to share with you the solution to the following exception when running jextract:
Exception in thread "main" java.lang.NegativeArraySizeException
This is a known issue which has already been fixed in the JVM, and shipped in SR8 FP1 for the Java SDK which is provided in WAS 184.108.40.206.
As a final tip, remember that if you’re running 64bit WebSphere 7, you’ll need to use the –J-Xcompressedrefs command line option with jextract.