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From "Shapira, Yoav" <>
Subject RE: Strage Behaviour - Tomcat Memory Leak
Date Thu, 05 Aug 2004 16:49:36 GMT

It depends on the size of your saw teeth: if they're small (<2MB), it
can be attributed to anything including internal JVM optimizations.
HotSpot will move things around in memory even when no "activity" is
taking place.

Also, what you're describing is not a leak by definition, since the
memory is reclaimed, i.e. nothing maintains references to it ;)

Yoav Shapira
Millennium Research Informatics

>-----Original Message-----
>From: Roberto Rios []
>Sent: Thursday, August 05, 2004 12:40 PM
>Subject: Strage Behaviour - Tomcat Memory Leak
>I was doing an evaluation of JProfiler in order see the improvements
>since the last time I used it. I has a feature (like other profilers)
>shows the heap usage in real time.
>As I always do, I have installed a new copy of tomcat, with NO changes.
>have just unziped it into a directory (by the way, I am using winXP,
>J2SDK1.4.2_05, JProfiler 3.1 and tomcat 4.1.30/5.0.25).
>So I started JProfiler, that automatically starts tomcat (I have tested
>against 4.1.30 and 5.0.25 - same behaviour), and I also started the
>monitor (that JProfiler calls VM Telemetry).
>What I saw, IMHO, is very strange: time to times (around every 30
>the heap is totally filled, and the garbage collector runs. So the
>looks like a saw:
>  /|  /|  /|  /
> / | / | / | /
>/  |/  |/  |/
>What is strange, is that I does't touch tomcat. I just start it.
Nothing is
>running under it (except the default applications: manager, examples,
>etc.... Anyway, I have cleaned the server.xml and webapps, removing the
>manager, admin and examples app. Same bahaviour again).
>IMHO, the heap usage should be a flat line if nothing is running under
>tomcat. Something like (the initial increase is due to tomcat startup)
>  /----------
> /
>My conclusion, is that OR tomcat has a huge memory leak, OR JProfiler
>Does anyone has an explanation about this behaviour? Is it know? Maybe
>listener, logger, etc?
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