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

[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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