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From "yilmaz" <yil...@hwajet.com.tw>
Subject Tomcat hangs if i click on refresh button
Date Sun, 02 Dec 2001 06:18:34 GMT
Hi guys,

Did any one expereince the following problem?
first let me tell my environment
i use tomcat4-b7, on win2000, my jvm is jdk1.3
i have a simple jsp file which simply dynamically displays images
the name of the images are dynamically created.
when first time i acess my jsp file, it compiles and displays the
images correctly without any problem, but for the second time it can't
display
whether i refresh the page or come back from another web address
it jsut displays a white blank page without any error.
Any idea about what is happening here, any logical expalantion?
or is it a kinda metaphysical phenomena :) (joking)
thanks for helping me
have a trouble -free weekend :)
yilmaz

----- Original Message -----
From: "Matt Egyhazy" <mwe7w@virginia.edu>
To: "Tomcat Users List" <tomcat-user@jakarta.apache.org>
Sent: Sunday, December 02, 2001 1:56 AM
Subject: Re: Known Memory clean-up issues?


> 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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