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From "Roberto Rios" <>
Subject RE: Strage Behaviour - Tomcat Memory Leak
Date Thu, 05 Aug 2004 19:35:24 GMT
Everybody is right. The saw teeth is around 3mb. The heap is around 9mb. So
after the GC runs, the available heap falls to 6mb.

As Yoah said this isn't a memory leak, since all the objects that area
created are garbage collected. I called it as a memory leak because even
with nothing running under tomcat, object were created.

I did an experience (following what Allistair wrote), removing loggers and
setting autodeploy to false. The saw pattern still occuring, but the cycle
is a little bit longer.

And, now that the "problem" is solved, I think that JProfiler is quite good.
It has some nice features. Since the last time that I have tested it, they
have improved a lot.



-----Mensagem original-----
De: Roberto Rios []
Enviada em: quinta-feira, 5 de agosto de 2004 13:40
Assunto: Strage Behaviour - Tomcat Memory Leak


I was doing an evaluation of JProfiler in order see the improvements did
since the last time I used it. I has a feature (like other profilers) that
shows the heap usage in real time.

As I always do, I have installed a new copy of tomcat, with NO changes. I
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 it
against 4.1.30 and 5.0.25 - same behaviour), and I also started the heap
monitor (that JProfiler calls VM Telemetry).

What I saw, IMHO, is very strange: time to times (around every 30 minutes)
the heap is totally filled, and the garbage collector runs. So the graph
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) this:


My conclusion, is that OR tomcat has a huge memory leak, OR JProfiler isn't

Does anyone has an explanation about this behaviour? Is it know? Maybe a
listener, logger, etc?



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