[jboss-user] [Beginner's Corner] - jboss as 4.2.2 high cpu usage

[viva div]

viva div [https://community.jboss.org/people/viva_div] created the discussion

"jboss as 4.2.2 high cpu usage"

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Hi!
We need some help with our jboss as version 4.2.2
For unknown reason java process uses 100% CPU after startup which makes applications unusable.
Platfort is virtualized SLES 10.
There were no changes made to OS or JBOSS/App.
Where to start?

Thanks
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[Wolf-Dieter Fink]

Wolf-Dieter Fink [https://community.jboss.org/people/wdfink] created the discussion

"Re: jboss as 4.2.2 high cpu usage"

To view the discussion, visit: https://community.jboss.org/message/796306#796306

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Might be that you have an issue with GC.
Check a thread dump whether a GC thread will consume all CPU.
Switch the gc logging on (see the http://www.oracle.com/technetwork/java/javase/gc-tuning-6-140523.html oracle java documentation for that)

Maybe it is simple and you have less memory configured for the JVM
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[viva div]

viva div [https://community.jboss.org/people/viva_div] created the discussion

"Re: jboss as 4.2.2 high cpu usage"

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Looked at heap dump and Permanent space is 99%. Also polling process shows a lot of time accounted for GC.
I guess you are right on GC issue. Now how do I fix it?
Tried to bump Xmx and xx:maxpermsize(512mb) but Permanent allocation is non resposive. Stays around 50mb.
I got this enviroment recently and not well familiar with sun jdk 1.5_15 issues.
We can throw more memory at it but not sure how.

Thanks
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[Peter Johnson]

Peter Johnson [https://community.jboss.org/people/peterj] created the discussion

"Re: jboss as 4.2.2 high cpu usage"

To view the discussion, visit: https://community.jboss.org/message/796430#796430

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Running the permgen at 99% is not a problem - the JVM will usually allocate just barely enough space for it because it is not volatile. So if you say it stays around 50MB, than a maxpermgen of 64MB should be more than enough. (Allocating more can actually work against you because it reduces the amount of memory that can be allocated to other areas of the JVM.)

If you suspect GC is the issue, you need to set one of the GC logging options, such as "-verbose:gc -Xloggc:gc.log", the data will appear in gc.log. Analyzing that data will tell you what is going on. To get some ideas on doing this, see my white papers at:
http://www.cmg.org/cgi-bin/search.cgi?q=java+peter+johnson&x=30&y=10 http://www.cmg.org/cgi-bin/search.cgi?q=java+peter+johnson&x=30&y=10
The 101 and 201 papers are handy, as well as the "Analyzing GC with R" (the R script calculates the % of time the process sent in GC).
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