Donnerstag, 23. Oktober 2008

Troubleshooting Memory Problems from IBM Systems with Memory Analyzer

There was one question which popped-up at every Memory Analyzer demo we did in the last couple of years – “Is the Memory Analyzer able to read heap dumps also from IBM VMs”? And we always had to give negative answers. Not any longer!
After some joint efforts it is now possible to analyze memory problems which occurred on IBM VMs with the help of IBM’s DFTJ technology and the Memory Analyzer tool.


The Diagnostic Tool Framework for Java (DTFJ) is a Java API from IBM used to support the building of Java diagnostics tools. Using one and the same API – DTFJ - tools can read data from different data sources in a unified way. The IBM DTFJ adapter enables MAT to work with system dumps from IBM Virtual Machines for Java version 6, version 5.0 and version 1.4.2.

Setting-up the Tools

In order to analyze IBM system dumps with Memory Analyzer, one needs to install the DTFJ adapter into the Memory Analyzer. The DTFJ adapter as well as installation instructions are available here.

Getting Data for Analysis

A detailed documentation on using DTFJ with MAT is added to the “Help” of MAT once the DTJF adapter is installed. There it is described how dumps can be obtained and pre-processed. Further reading about DTFJ can be found in the “Diagnosis documentation”

Here I will only roughly present the process:

  • Get a system dump from the Java process

  • Run the jextract tool on the system where the dump was taken. This will produce a zip file which can be then analyzed on an arbitrary system

  • Open the jextract-ed file with the Memory Analyzer (which, of course, has the DTFJ adapter installed)

  • The minimum-required versions of the IBM JDKs are:

  • Java 1.4.2 SR12

  • Java 5 SR8a

  • Java 6 SR2

  • Analyzing the DTFJ Extracted Dumps

    The analysis with the Memory Analyzer remains the same as for HPROF dumps. This means that if you have already some experience with the tool, you can just continue to do the analysis in the same way did before also for IBM dumps.

    If you are new to the tool and need some “first steps” help, here are some resources which could help:

  • Look at the “Getting Started” part from the help coming with the tool

  • Look at our Blogs

  • Watch the recorded Eclipse webinar

  • If you want to see the Memory Analyzer & DTFJ in action, you can visit the “New & Noteworthy” short session at Eclipse Summit Europe 2008.

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