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From Simon Pabst <simon.pa...@web.de>
Subject Re: Need help with performance issue - Tomcat 4.1.X
Date Fri, 11 Jul 2003 20:35:40 GMT
If your application is running on same Tomcat/JVM then blocking GC calls 
could still lead to that effect for hello.jsp too.

Are you using Apache/mod_jk/Tomcat or Tomcat standalone?
HTTPS Connections?

Does the Problem occur only with IE or with other Browsers (Mozilla) too?
I read once something about a problem of IE closing http connections too 
fast when it thinks the page transfer is finished.

At 20:08 11.07.2003 +0000, you wrote:
>We are currently starting up with -Xmx256M.  Java is currently using about
>327MB and has been that way for hours.  I haven't really seen any fluxuations
>at all, which leans me away from the garbage collection issue.
>
>I created a hello.jsp, which is completely separate from our 
>application.  Same
>results.  It takes about 30 seconds to return.
>
>In the hello.jsp, the results of the page return instantly to the browser, 
>but
>then it's as if tomcat just won't close the connection to the browser.  The
>page is there, fully rendered, but just sits there waiting for the server to
>tell it it is done.  Is there some way that the tomcat connections could be
>failing to terminate properly?
>
>
>Our current maxProcessors = 75
>acceptCount = 10 (which is probably low but right now we have only a couple
>users on the system).
>
>We're not using 1.4 so those options are out.
>
>-- Dave
> > Could be a Memory Leak/Garbage Collection issue (we had a similar problem
> > with a memory intensive app),
> > maybe your heap is too small and java is running many Full GC's.
> > Start java with -verbose:gc and look in tomcat/logs/catalina.out for
> > Garbage Collections.
> > (set Environment Variables JAVA_OPTS or CATALINA_OPTS in 
> bin/catalina.sh to
> > do this in Tomcat)
> >
> > ================================
> >
> > Try using a bigger Heapsize (though if you've got a Memory Leak that will
> > only delay your problem)
> > or set initial Heapsize to same as maximum, for example 128MB:
> > -Xmx128m -Xms128m
> >
> > ================================
> >
> > Modify the Connector you are using to access Tomcat (in
> > tomcat/conf/server.xml) and
> > try using more Tomcat Processors (maxProcessors=XX) or a bigger accept
> > queue length (acceptCount=XX)
> > (test value for acceptCount: at least > concurrent users x 3)
> >
> > ================================
> >
> > Try using another method of garbage collection,
> > if you're using JDK 1.4.1 i'd try either
> >
>
> > ConcurrentGC with ParNewGC (ParNewGC on Multi-CPU machines):
> > -XX:+UseConcMarkSweepGC -XX:+UseParNewGC
> >
> > or ParallelGC with AdaptiveSizePolicy (saves you the work of Java Heap
> > usage analyzing :-) :
> > -XX:UseParallelGC -XX:+UseAdaptiveSizePolicy
> >
> > A good article on GC can be found here:
> > http://wireless.java.sun.com/midp/articles/garbagecollection2/
> >
> > ================================
> >
> >
> > At 18:04 11.07.2003 +0000, you wrote:
> > >With Tomcat 4.1.x
> > >
> > >We've recently run into an issue where some of our pages either
> > >a) take a really long time to come up (20+ seconds)   or
> > >b) come up, but never really finish loading (the status bar in IE shows
> > >the the
> > >response hasn't finished).
> > >
> > >These are very simple pages (for example, a login page) and our server
> > >load is
> > >minimal (maybe 10 concurrent users).  Then, mysteriously, the problem 
> will go
> > >away by itself.  It will also return.
> > >
> > >Given the information above, I'm not expecting any solutions, but I 
> could use
>
> > >some help steering me in the right direction with things to check.  We're
> > >hooking up monitoring on the systems (Linux) to examine memory and CPU
> > >utilization during the slowdowns.
> > >
> > >Any things in particular we should be examining to try to find the 
> problem?
> > >Any idea why the pages would never fully return from the server?
> > >
> > >TIA
> > >
> > >-- Dave
> > >
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>
>
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