Java dumps

I recently had to debug a problem with the MDM Workbench where exporting a tailoring project for Information Server didn’t do anything. In fact it didn’t even report any problems!

Unfortunately the code in question likes to put a brave face on things and just reports that everything was OK, even when something goes wrong. This was the perfect opportunity to try out some of the diagnostic tools available for the IBM Java runtime, which I’ve been meaning to try for ages. I had an idea where the problem was likely to be but to find out for sure I started the workbench using the following command line:

eclipsec -vmargs -Xdump:system:events=catch,filter=java/lang/AbstractMethodError#com/ibm/mdm/tools/export/infoserver/job/MDMDatabaseDAO.queryDatabaseWithoutFilter

Sure enough the failing export produced a dump which I could check using the Memory Analyzer tool. You can get the IBM version via IBM Support Assistant but it’s probably easier to get the standard Eclipse Memory Analyzer and add the required IBM plugins from the DTFJ update site.

I’m fortunate enough to work in Hursley so I could pester someone who works on IBM Java runtime diagnostics, but there’s also a helpful article on developerWorks with details of how to trigger dumps, and how to run queries using OQL:

Debugging from dumps: Diagnose more than memory leaks with Memory Analyzer

So mystery solved- if you have an Oracle database and want to exporting tailoring projects for Information Server, make sure you set up the database connection with a more recent JDBC driver than the defaults.

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