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From Randy Layman <randy.lay...@aswethink.com>
Subject RE: Growing Memory
Date Mon, 13 Aug 2001 13:19:00 GMT

	I believe about the only thing that the JDBC-ODBC bridge, provided
with Java by Sun, doesn't do is leak memory.  It does have threading issues
and it will cause a General Protection Fault/Application Error/Dr. Watson
error, depending upon your version of Windows.  (In Sun's Bug Parade they
indicate that the bridge is experimental, unsupported, and not recommended
for any actual usage.)

	In your case, its not your database drivers.  One other thing that I
didn't mention before, remember that your servlet instance variables will
also be around (practically speaking) from first invoation/initalization
until the container stops.  Having lists and maps here that can accumulate
data can also cause problems.

	Randy

> -----Original Message-----
> From: Scott Weaver [mailto:sweaver@wirelesstelematics.com]
> Sent: Monday, August 13, 2001 9:41 AM
> To: tomcat-user@jakarta.apache.org
> Subject: RE: Growing Memory
> 
> 
> Thanks for the info.
> 
> I am using the JDBC driver in my servlets 
> (jdbc:odbc:driver={SQL SERVER}).
> This might be where my problem is.
> 
> What is the problem with this driver and is there a work around?
> ... or should I say, What is a common miss configuration?
> Do you know where I can see a correct configuration or do you have an
> example?
> 
> Thanks again,
> Scott
> 
> -----Original Message-----
> From: Randy Layman [mailto:randy.layman@aswethink.com]
> Sent: Monday, August 13, 2001 8:26 AM
> To: tomcat-user@jakarta.apache.org
> Subject: RE: Growing Memory
> 
> 
> 
> 	You could try one of the profiling tools out there (we 
> use a very
> old version of OptimizeIt) to spot where the memory is going 
> and how it got
> there.
> 
> 	A few things that could be your problem, though:
> 	1. You are putting very large objects into sessions and your
> sessions have long or no expiration times
> 	2.  You have an object with a static variable that you 
> keep adding
> to (map, list, set, etc) and aren't ever clearing
> 	3.  You have some form of buffered IO where the buffer 
> isn't being
> flushed.
> 
> 	Realize that these are the end causes of your memory leak.  You
> might be using some library (like JDBC drivers) that could 
> cause one or more
> of these issues if they are miss configured.  If its possible, I would
> suggest that you try using your servlets one at a time and spot which
> servlet is causing the memory to go up.
> 
> 	Randy
> 
> > -----Original Message-----
> > From: Scott Weaver [mailto:sweaver@wirelesstelematics.com]
> > Sent: Monday, August 13, 2001 9:00 AM
> > To: tomcat-user@jakarta.apache.org
> > Subject: Growing Memory
> >
> >
> >
> > I've been using Tomcat with IIS 5.0 on a dual processor
> > machine running
> > Windows 2000.
> >
> > The memory usage just seems to grow over use and I'm not sure
> > where to look
> > for problems.
> >
> > Anyone have any experience with this problem?
> > And/Or advice on what to look at to try to diagnose this problem?
> >
> > Thanks for the help,
> > Scott
> >
> 

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