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Hung Threads in WebSphere

 
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Hi,
I have come across a problem in my production environment to do with hung threads in WebSphere. It seems that one of our four clones looked as if it was running through in the admin console but my infrastructure people were only able to perform a restart by killing the aix process and then restarting the clone. (I haven't yet identified if it happens on the same clone all the time)We are currently running WAS network deployment version 5.1.1.6. I have checked the fix list for 5.1.1.7-5.1.1.8 and cannot see any WAS installation mentioning this. From looking at IBM's advice on this it says that hung threads can be pretty much caused from system resources problems to infinite loops in the application code and my infastructure people are putting the cause of the hung threads down to this . As it appears no performance metrics were analyzed on this system ever this is my next step to trying to find the cause.(On our UAT system). The question I want to ask is , can anyone advise on how they would tackle such a problem.
I have read that there are ways to initiate a java thread dump that may give more information on the problem ?? Any help on this would be much appreciated.
 
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I use kill -3 on a running production environment (AIX) without any problem. gives a java core txt file that you can analyse (i think the tool is on developerworks).
(but make sure you do it in test before trying it in production)

I have seen hung threads in a situation where websphere 4 acted as java-client. solution was upgrading websphere 4 with the latest security fix
 
Brian Hennessy
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Thanks for that Sandar. I'll check out the developerworks to get more info on interpreting the java core dump output.


However before I attempt this in Test do you know how long the java core dump takes , roughly how big the file normally is and are there any other problems I should be aware of running the kill -3 option.

Thanks again
[ January 24, 2006: Message edited by: hennesb hennesb ]
 
sander hautvast
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our machines are pretty fast, and I don't know about yours...
but it takes just a second or less
 
sander hautvast
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and the files are about 2Mb in size
 
Brian Hennessy
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Sander

Thanks again for that , we haven't experienced the problem since last week but have run the suggestion of the kill -3 past our WAS admin people and next time we experience the problem they'll initiate the dump.


Rgds
Hennesb
[ January 25, 2006: Message edited by: hennesb hennesb ]
 
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Can someone help me with server crash fixing.
I get the j9.dmp server crash, when I run my code in WSAD 5.1 in debug mode.
Java version: jdk 1.4.2_07


thanks, sri
[ January 28, 2006: Message edited by: Sri Addanki ]
 
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