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From "Neil Aggarwal" <>
Subject Tag Handler pool eating up Memory (and enablePooling is set to false)
Date Mon, 01 Dec 2003 22:52:40 GMT

We have several tomcat servers running an application.  The servers
slow down after a few hours of uptime.

Looking at the memory usage on the servers, we noticed that the servers
seem to be accumulating memory and finally they slow down when
the memory utilization becomes high.

We are using the IBM JDK 1.4.1 SR1 with Tomcat 4.1.24 on RedHat 9.

Using the heapdump utility from the IBM JDK, I generated a heap dump
from one of the servers after it had been up for a while.

>From that output, I see these pieces of infromation:

There were a total of 509,235 objects in memory 
taking up 67,992,688 bytes.

There were 436 instances of org/apache/jasper/runtime/TagHandlerPool.
Tracing all of the references from these TagHandlerPool object,
they reference a total of 65,010,600 bytes.

This means that almost 97% of the memory usage of Tomcat is being 
referenced from the TagHandlerPool objects.

I have enablePooling set to false in the Tomcat's web.xml in the conf 

It seems that the enablePooling setting is not preventing Tomcat from
pooling the tag handlers and they are referencing a lot of memory.

Does that setting work in Tomcat 4.1.24?

Is there any other reason why Tomcat would behave this way?


Neil Aggarwal, JAMM Consulting, (972)612-6056,
FREE! Valuable info on how your business can reduce operating costs by 
17% or more in 6 months or less! =>

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