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From "Caldarale, Charles R" <Chuck.Caldar...@unisys.com>
Subject RE: Tomcat memory question
Date Tue, 14 Jun 2005 13:48:10 GMT
> From: Tim Funk [mailto:funkman@joedog.org] 
> Subject: Re: Tomcat memory question
> 
> But class definitions (IIRC) do not go onto the heap so you 
> could have a lot of classes without any worries.

Actually, an instance of java.lang.Class is created for each
classloader/class combination, and these are in the heap - in the
Permanent Generation for HotSpot-based JVMs.  Besides the dozen or so
Java fields in each instance of java.lang.Class, the JVM keeps quite a
bit of additional information (e.g., method table pointers) in each
instance that is visible and accessible only to the JVM itself, not any
Java code.  Running a large number of webapps in Tomcat will often
require increasing the portion of the total heap that is assigned to the
PermGen.  You can find some discussions about this in the archives.

 - Chuck


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