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Is it possible to find out a class' generation using MAT? [message #775426] Fri, 06 January 2012 00:28 Go to next message
veggen skrikk is currently offline veggen skrikk
Messages: 3
Registered: January 2012
Junior Member
Hi all.

This might be a very silly question, but I'm completely new to MAT. I'm interested to know if it's possible to know a class' generation (a number of GC runs it's instances survived) using MAT?
I've seen this feature in VisualVM and was wondering if MAT has it as well, or if it's purely a dump analyzer?

P.S.
Am I correct to think generation info can not be acquired from a dump as it requires class instrumentation?

Thanks.

[Updated on: Fri, 06 January 2012 01:20]

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Re: Is it possible to find out a class' generation using MAT? [message #775634 is a reply to message #775426] Fri, 06 January 2012 12:18 Go to previous messageGo to next message
Jonathan Lawrence is currently offline Jonathan Lawrence
Messages: 16
Registered: July 2009
Junior Member
Hi Veggen,

You're right that generation info cannot be obtained using MAT. It is a dump analyzer and so works with a snapshot of the heap and has no additional meta-information on classes or instances. As MAT is intended to work with many different VMs, there is no custom instrumentation which can be relied upon.

There are two other tools which may be of interest/use to you in monitoring/diagnosing your application, these are:
1) IBM Monitoring and Diagnostic Tools for Java - Garbage Collection and Memory Visualizer:
The Garbage Collection and Memory Visualizer (GCMV) helps visualise the memory footprint, garbage collection behaviour and performance of Java Applications using verbose garbage collection output. The Garbage Collection and Memory Visualizer provides recommendations for tuning the application.
2) IBM Monitoring and Diagnostic Tools for Java - Health Center:
The Health Center is a lightweight tool that monitors active IBM Virtual Machines for Java with minimal performance overhead. The Health Center suggests live tuning recommendations for Garbage Collection, profiles methods including call stacks, and highlights contended locks.

Health Center has a garbage collector view which shows live graphical statistics on GC performance. It works with IBM VMs only.

Both the above tools are available as Tool Add-ons through the IBM Support Assistant:
http://www-01.ibm.com/software/support/isa/download.html

These tools do not however provide explicit generation information for individual classes/instances.
Re: Is it possible to find out a class' generation using MAT? [message #775647 is a reply to message #775634] Fri, 06 January 2012 12:56 Go to previous message
veggen skrikk is currently offline veggen skrikk
Messages: 3
Registered: January 2012
Junior Member
Thanks for a great response Jonathan Smile
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