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From Sameer Acharya <>
Subject Re: Would like to monitor memory use offline
Date Mon, 04 Aug 2008 05:00:37 GMT
You can write a simple JSP which will run a freeMemory/totalMemory call in your JVM and possibly
send a mail/log when the limits are reached.

You could set a refresh interval and have this page refresh say every 5 minutes in your browser.

Alternatively you can tweak with the manager app code.

If you are an administrator ten from a long term monitoring aspect you may want to explore
the usage of Lambdaprobe.


--- On Sun, 8/3/08, Richard S. Huntrods <> wrote:

> From: Richard S. Huntrods <>
> Subject: Would like to monitor memory use offline
> To:
> Date: Sunday, August 3, 2008, 7:48 AM
> I've been running Tomcat for many versions now, mostly
> without incident. 
> However with the latest set of upgrades rather
> "forced" upon me all at 
> once (instead of managed more properly), my application
> appears to have 
> a severe memory leak.
> System Info: OS is Solaris 10-u5 (2008); java 1.6.0_06-b02;
> apache-tomcat-6.0.16; mysql 5.0.51a-solaris10-x86_64. I
> have fast 
> servers and plenty of memory (8 gigs). I'm running 1
> gig stack and 
> getting at least 2 GC/stack exceptions per day (sometimes
> more). Yes - 
> it's a user/use triggered leak but I can't trace it
> further yet.
> Of course what is odd is that there was NO memory leak
> using older 
> versions of this stuff (Solaris 10 (2006), java 1.5.x,
> tomcat 5.5.12, 
> mysql 5.0.16). I'm sure the memory leak was there, but
> it was "well 
> masked". On the older system I was running 512 meg
> stack and it never 
> gave GC or stack errors.
> So, while I am actively trying to fix the memory leak, I
> still have to 
> maintain these production servers at operatonal status
> (politics - don't 
> ask). However, it's difficult as the memory leak is
> causing repeated GC 
> and "out of stack" exceptions.
> What I've noticed recently is that when using the
> manager application, I 
> can watch the memory utilization grow and more memory get
> allocated (via 
> refreshing the page), right up until the stack is used up
> and the main 
> application crashes. However, if I'm watching it grow,
> and then log on 
> to the server and reset tomcat (stop and then start
> tomcat), the memory 
> use is back at the start. Thanks to session persistence, no
> users are 
> "harmed" during this exercise.
> So for the moment, while I try and debug the application, I
> can keep 
> things running by having a cron job periodically reset
> tomcat for me. 
> But this is really crude. Until I fix the memory leak,
> I'd like 
> something a little bit more elegant.
> SO - my question - is there a relatively easy way to create
> something 
> (say a servlet) to watch the stack *just like I can do
> manually using 
> the manager application* but email me when the stack
> approaches the 
> memory limits?
> Thanks,
> -Richard
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