Re: Java Problem Analysis
- From: Larry.A.Gray@xxxxxxxxx (Gray, Larry - Larry A)
- Date: 18 Dec 2007 09:25:35 -0800
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Thanks. I will check them out.
I do analyze the verbosegc output using the ISA. No problem with that.
Larry Gray
Large Systems Engineering
Lowe's Companies
336-658-7944
-----Original Message-----
From: IBM Mainframe Discussion List [mailto:IBM-MAIN@xxxxxxxxxxx] On
Behalf Of Michael Poil
Sent: Tuesday, December 18, 2007 11:10 AM
To: IBM-MAIN@xxxxxxxxxxx
Subject: Re: Java Problem Analysis
I have tried to use the heap dump analyzer off the ISA before, but had
trouble with it never giving me anything useful (probably me not knowing
how to use it correctly). I found I had a lot of the same objects, but
could never get it to show me the name of the object. If there were
things to look for from the WAS perspective under java, that might also
help.
Try
WAS http://www.redbooks.ibm.com/abstracts/redp3950.html
HeapAnalyzer and many useful links
http://www-1.ibm.com/support/docview.wss?uid=swg27006624
EVTK and ISA
http://www.ibm.com/developerworks/web/library/j-ibmtools2/?S_TACT=105AGX
54&ca=dnw-839
You can run HeapAnalyzer without ISA - see the second URL tabs (I use it
outside ISA for PMRs). Dealing with object leaks is not always
straightforward, but the general idea is to find the object tree with
the most storage, click down its hierarchy and find where there is a big
drop between the size of a level of the tree and the next and that is
where you often find the leaked objects - see the doc that you can get
at via the second URL.
If you want to analyse verbosegc output, use ISA and EVTK (or find
GCCollector or PMAT). This is useful for Java performance analysis as
cpu problems may be nothing more than the Java Heap is too small or some
of the command line parameters are set badly e.g. -Xloratio is too big.
If anyone wants some very simple rules of thumb, ask me.
Regards.
Mike
------------------------------------------------------------------------
------------------------------------------
Mike Poil
Java z/OS Level 3 Service
IBM United Kingdom Limited, Hursley Park, Winchester SO21 2JN
Internal: 246824 External: +44 (0)1962 816824 Java debugging:
http://www.ibm.com/developerworks/java/jdk/diagnosis/
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