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From: teknokrat <teknokrat@yahoo.com>
Subject: Re: Memory Usage - Tomcat 5.0.25
Date: Wed, 11 Aug 2004 14:37:33 +0100
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Nandish Rudra wrote:
> Hello Everyone,
> 
> I am writing about this error from yesterday. I used JProfiler to monitor my
> memory usage. And am now sure that each and every static object is trashed
> when the application is undeployed and the profiler shows that memory is
> free and all instance of the objects are GC'd. This works on a Windows 2000
> setup of Tomcat 5.0.25 with Java 2 SDK version 1.4.2_04 and Ant 1.6.1, but
> fails miserably on GNU Linux 2.4.20-8 setup. this happens with both tomcat
> 5.0.25 and 5.0.27
> 
> Any ideas why something like this could be happening.
> 
> Nandish Rudra
> ECI Conference call Service LLC.
> 
> -----Original Message-----
> From: Shapira, Yoav [mailto:Yoav.Shapira@mpi.com]
> Sent: Monday, August 09, 2004 1:35 PM
> To: Tomcat Users List
> Subject: RE: Memory Usage - Tomcat 5.0.25
> 
> 
> 
> Hi,
> I have a couple of ideas.  One is that your webapp maintain static or
> shared references to objects that prevent them from being garbage
> collected, and therefore memory from returning to the heap.  Another is
> that a webapp undeploy is not guaranteed to reclaim all memory used by
> the webapp anyways so to count on this behavior is not smart.  It is
> expected that every time you reload your webapp the overall memory usage
> of the server will go up a bit, as not all objects are gone (for
> example, if you have a static reference than the old classloader and
> anything that references it strongly will remain in memory).
> 
> Yoav Shapira
> Millennium Research Informatics
> 
> 
> 
>>-----Original Message-----
>>From: Nandish Rudra [mailto:nrudra@calleci.com]
>>Sent: Monday, August 09, 2004 1:17 PM
>>To: Tomcat Users List (E-mail)
>>Subject: Memory Usage - Tomcat 5.0.25
>>
>>Hello,
>>
>>I am having some memory issues while deploing/undeploying web
> 
> applications
> 
>>to Tomcat. I am using Tomcat 5.0.25 with Java 2 SDK version 1.4.2_04
> 
> and
> 
>>Ant
>>1.6.1 on GNU Linux 2.4.20-8. I use ant to compile my web application
> 
> and
> 
>>Tomcat's catalina-ant.jar to deploy it automatically.
>>
>>Here is my problem. When I undeploy/remove an application, Tomcat does
> 
> not
> 
>>reclaim the memory being used by the web application and when the
>>application is re-deployed/re-installed a significant increase in
> 
> memory is
> 
>>seen. This increase is obviously the memory usage by the new instance
> 
> of
> 
>>the
>>web application.
>>
>>Does anyone have any idea as to why this is happening?
>>

Try looking at jvmstat (http://developers.sun.com/dev/coolstuff/jvmstat/)

My own tests with show that its the permanent space of objects that gets 
  filled up and not reclaimed after each reload.


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