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Websphere application Server Performance.

Krupa Eng
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Joined: Sep 05, 2003
Posts: 60
My webapplication on WEBSPHERE APPLICATION SERVER 5.0 becomes irresponsive for 30 to 40 seconds every now and then(like once everyday). How do I go about finding the culprit?
Thanks,
Krupa


Krupa
Jeanne Boyarsky
author & internet detective
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Joined: May 26, 2003
Posts: 30780
    
157

Krupa,
Check the websphere logs.


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Kyle Brown
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Joined: Aug 10, 2001
Posts: 3892
    
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And if that doesn't help, start the JVM with -verboseGC and see if it isn't garbage collecting when you have it go unresponsive.
Kyle


Kyle Brown, Author of Persistence in the Enterprise and Enterprise Java Programming with IBM Websphere, 2nd Edition
See my homepage at http://www.kyle-brown.com/ for other WebSphere information.
Krupa Eng
Ranch Hand

Joined: Sep 05, 2003
Posts: 60
I have seen the logs with GC -verbose and I noticed that for every 2 minutes the I see the message
starting collection, threshold allocation reached.

Does this mean that the garbage collection is happening for every 2 minutes and if so is it normal for garbage collection to run every 2 minutes
Vinod Bijlani
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Joined: Mar 06, 2002
Posts: 133
1 scenario which i have faced this is - plugin refreshing at the time we are having high volume. there is no respsone until the webserver is done refreshing the plugin. BUT THIS WAS AT THE WEBSERVER NOT THE APPSERVER.
Naveen Kumar
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Joined: May 29, 2002
Posts: 30
Hi
If the JVM is going for a GC, since you have enabled -verbose, you should be able to see some entries like below.
[GC 30464K->2597K(523136K), 0.0684625 secs]
[Full GC 16189K->2703K(523136K), 0.2983244 secs]
This indicates that JVM is performing a GC.
But "starting collection" etc, I have never seen in the logs, I suppose they might not be related to GC.
But you can consider GC running for every 2 minutes to be normal. But again why dont you increase the heap size (initial & max) allocated and then check.
Regards
Naveen Kumar
[ February 03, 2004: Message edited by: Naveen Kumar ]
Krupa Eng
Ranch Hand

Joined: Sep 05, 2003
Posts: 60
Vinod,
Can you explain me a little further on how to check that webserver plugin refresh. Is there any way we can change the plugin refresh interval?
Thanks
Vinod Bijlani
Ranch Hand

Joined: Mar 06, 2002
Posts: 133
grep for refreshInterval in plugin-cfg.xml
I think there is a default value as 60 seconds in v501
Change this value & restart the webserver
Krupa Eng
Ranch Hand

Joined: Sep 05, 2003
Posts: 60
Thanks so much for your help.
How can we gain performance by changing this refresh interval. Is there any log where we can see when the refresh is happening?
Krupa Eng
Ranch Hand

Joined: Sep 05, 2003
Posts: 60
Some thing is really wrong about our WAS Configuration.
The startup and stop times for WAS are terrible.

Can some one provide me cheat sheets to check these performance things.
I looked at several performance docs from IBM Website and tried several things they talked about, like changing the heap size, Garbage collector monitoring and tuning and I don't see the performance improvements. May be I am missing some thing else.
Thanks,
Benny Thomas
Ranch Hand

Joined: Sep 13, 2003
Posts: 44
I am facing some issues of Out of Memory on my WAS 4 application.
When 4-5 users log in to a 1 GB RAM machine, the server crashes.
How do i monitor the jvm in WAS 4?

Please help.

Thanks in advance

Benny


IBM Certified System Administrator - Websphere Application Server 5
David Ulicny
Ranch Hand

Joined: Aug 04, 2004
Posts: 724
Try the -verboseGC like was mentioned above or you can start PMI and check the logs with Tivoli Performance Viewer.
You could also use some profiler to check what is happened in your application.


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subject: Websphere application Server Performance.