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DTFJ Error Opening Core Dump [message #1816032] Thu, 17 October 2019 17:24 Go to next message
Frank Ball is currently offline Frank BallFriend
Messages: 1
Registered: October 2019
Junior Member

I'm trying to open a WebSphere core.dmp file using Memory Analyzer with DTFJ installed and getting this exception:

java.lang.NoSuchFieldError: J9_JAVA_CLASS_RAM_ARRAY
	at org.eclipse.mat.dtfj.DTFJIndexBuilder.fill(
	at org.eclipse.mat.parser.internal.SnapshotFactoryImpl.parse(
	at org.eclipse.mat.parser.internal.SnapshotFactoryImpl.openSnapshot(
	at org.eclipse.mat.snapshot.SnapshotFactory.openSnapshot(

It seems related to this J9 bug:

Is this something that should be submitted as a bug under MAT at or is there another place to submit DTFJ bugs?

Re: DTFJ Error Opening Core Dump [message #1816426 is a reply to message #1816032] Tue, 29 October 2019 10:39 Go to previous messageGo to next message
Andrew Johnson is currently offline Andrew JohnsonFriend
Messages: 149
Registered: July 2009
Senior Member
This is a DTFJ bug not an Eclipse Memory Analyzer bug. IBM Diagnostic Tooling Framework for Java is a set of classes which allows analysis of dumps from IBM VMs. There is a separate Eclipse format update site which allow any VM to be used. Unfortunately this has not been updated for over a year.

If you have an IBM support contract for IBM WebSphere Application Server you could try asking IBM for the DTFJ update site to be updated with the latest DTFJ as the old version is stopping you debug your application problems.

You could try asking OpenJ9 what the plans are creating a Eclipse update site including DTFJ, as there is an OpenJ9 DTFJ module

As a work-around you could try replacing the dtfj.jar somewhere under the Eclipse Memory Analyzer directory mat\configuration\org.eclipse.osgi with the latest dtfj.jar from your VM.
Re: DTFJ Error Opening Core Dump [message #1816969 is a reply to message #1816426] Wed, 13 November 2019 08:17 Go to previous message
Dave Nice is currently offline Dave NiceFriend
Messages: 5
Registered: July 2009
Junior Member
Thanks for the tip, Andrew.

I found that dtj.jar and dtfj-interface.jar seemed to have been combined, but I found a dtfj.jar and a j9-ddr.jar in the new VM and replaced both the existing dtfj.jar and dtfj-interface.jar with the new dtfj.jar, and j9-ddr.jar with the new j9-ddr.jar. These were all within the plugins directory, in plugins called*.

After this I was able to carry on.
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