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From Matt Egyhazy <mw...@virginia.edu>
Subject Re: Known Memory clean-up issues?
Date Sat, 01 Dec 2001 17:56:12 GMT
have you tuned the jvm settings?  i had out of memory errors with 3.2.3
version of tomcat after periods of heavy load until i tuned the jvm.

matt
----- Original Message -----
From: "Randy Layman" <randy.layman@aswethink.com>
To: "Tomcat Users List" <tomcat-user@jakarta.apache.org>
Sent: Thursday, November 29, 2001 3:25 PM
Subject: RE: Known Memory clean-up issues?


>
> The best thing you can do is to find out where YOU are leaking
> memory.  Tools like OptimizeIt are very useful for this type of issue.
Here
> are a few hints that might help you:
> * Sessions stick around for some time after the user leaves.  If you
> have large amounts of data in the session, you might want to make your
> timeout smaller
> * Servlet instances stay around for very long amounts of time.
> Storing anything in static and/or instance variables of the servlet can
> consume memory for very long amounts of time
> * Static fields stay around for very long amounts of time, even if
> there are no more references to the classes
>
> Another tip, if you reduce the Heap size of your JVM then you can
> get the problem to happen quicker (since there's less memory available to
> leak).
>
>
> >From the JavaDoc on java.lang.OutOfMemoryError:
> "Thrown when the Java Virtual Machine cannot allocate an object because it
> is out of memory, and no more memory could be made available by the
garbage
> collector."
>
> Something is holding onto lots of memory.  If your servlet is
> holding memory and a request comes it, its possible that the servlet is
> holding enough memory that Tomcat can't get the memory that it needs to
> service the request.
>
> Randy
>
>
> > -----Original Message-----
> > From: Denis Balazuc [mailto:denis.balazuc@trader.com]
> > Sent: Thursday, November 29, 2001 3:42 PM
> > To: Tomcat Users List
> > Subject: Re: Known Memory clean-up issues?
> >
> >
> > Hi all
> >
> > Where would you recommend to use System.gc() in the context
> > of JSP pages ?
> > I guess it would be useless to intercept every single request
> > and hint the
> > system for garbage collection on each request ?
> >
> > (Now I quote)
> > "Also, before an OutOfMemory is thrown, the Garbage collector is
> > guarenteed to run, meaning that you really are using all of
> > your memory.  I
> > would look at what you are doing in your code - I have
> > servlets that run for
> > weeks without eating up any significant portion of memory"
> >
> > I do have many times OutOfMemory exceptions thrown, although
> > we're not doing
> > *that* much....
> > It happens quite randomly so it's very difficult to isolate
> > the problem.
> > Moreover, it even happens when fetching HTML pages from
> > Tomcat, without
> > using much JSP...
> > I'd like to find a place to catch that error to take action
> > (like restarting
> > Tomcat) but the only way we have found is to monitor the server and
> > automatically restart it when it fails to respond.
> >
> > Any guidance to solve the problem would be appreciated ;-)
> >
> > Thanks
> > Denis Balazuc
> >
> >
> > ----- Original Message -----
> > From: "Yoav Shapira" <shapira@mpi.com>
> > To: "Tomcat Users List" <tomcat-user@jakarta.apache.org>
> > Sent: Thursday, November 29, 2001 03:07 PM
> > Subject: Re: Known Memory clean-up issues?
> >
> >
> > > Howdy,
> > >
> > > > Any harm in forcing garbage collection to run?
> > >
> > > You cannot force garbage collection to run, only suggest it to the
> > > JVM via methods like System.gc().  If you're having difficulty
> > > tracking down memory usage, try a profiler like OptimizeIt that has
> > > entire memory trees.
> > >
> > > In addition, you can use parameters like hprof and verbosegc on
> > > the java command line to assist you in monitoring garbage
> > collection.
> > >
> > > Yoav Shapira
> > >
> > > --
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