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Websphere application Server Performance.

 
Krupa Eng
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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
 
Jeanne Boyarsky
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Krupa,
Check the websphere logs.
 
Kyle Brown
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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
 
Krupa Eng
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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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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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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
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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
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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
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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
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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
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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
 
David Ulicny
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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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