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From "Leon Rosenberg" <rosenberg.l...@googlemail.com>
Subject Re: Tomcat problem on a multiple CPU system
Date Tue, 06 May 2008 07:08:57 GMT
just 2 cents, if your 8 IEs are running in one process, which is
default to my knowledge, they are sharing the same urlhelper/toolkit
which default to 4 max parallel connections.
I suggest you write a small java programm that tests it for you (with
commons-httpclient) or use jmeter or at least wget/curl.

regards
Leon


On Mon, May 5, 2008 at 1:10 PM, Gilbert, Antoine <AGilbert@korem.com> wrote:
> I open 8 IE on a remote computer, basically once a JSP is called, the
>  browser is just waiting the process to be done.
>
>
>
>  -----Original Message-----
>  From: David Smith [mailto:dns4@cornell.edu]
>  Sent: 4 mai 2008 23:00
>  To: Tomcat Users List
>  Subject: Re: Tomcat problem on a multiple CPU system
>
>  Can you describe how you open the 8 browser windows and what browser you
>
>  are using?  I ask because those 8 browser windows may be coming from one
>
>  process and using at most 2 connections, hence the slower processing.
>  Firefox normally only has one process no matter how you open the new
>  windows.  IE can be 8 separate processes if you launch each separately
>  from Explorer (ie the Start button or desktop shortcut) and not use the
>  new window menu option or ctrl-n.
>
>  --David
>
>  Gilbert, Antoine wrote:
>  > Well, each process is a image rendering process.
>  >
>  > But my point is, if I launch 8 threads directly in a JVM outside of
>  > tomcat, it run faster and use 100% of the 8 CPU...
>  >
>  > If I make a Servlet (or a JSP) who will start a process each time I
>  call
>  > it (I call it 8 times).
>  >
>  > So, the big question is, why It's fast directly on the JVM and it's
>  slow
>  > on Tomcat ? Why with Tomcat It's not possible to use 100% of all the 8
>  > CPU ? There is no data transfer between client and server, in both
>  case
>  > the images are rendered on the disk.
>  >
>  > I just made this rendering test to expose the fact that I'm unable to
>  > make my tomcat use efficiently all my CPU.
>  >
>  > So the big question, why these 8 processes run betters than these 8
>  > process within Tomcat ?
>  >
>  >
>  >
>  > -----Original Message-----
>  > From: Alan Chaney [mailto:alan@compulsivecreative.com]
>  > Sent: 4 mai 2008 17:33
>  > To: Tomcat Users List
>  > Subject: Re: Tomcat problem on a multiple CPU system
>  >
>  > Hi Antoine
>  >
>  > The thing to remember is that this is a system which has (at least)
>  four
>  >
>  > main parts:
>  >
>  > 1. Tomcat
>  > 2. The operating system
>  > 3. A network connection
>  > 4. Your application
>  >
>  > (and potentially)
>  >
>  > 5. A database (but you didn't mention that)
>  >
>  > Here are some questions.
>  >
>  > 1. How do you make the connection to the servlet. Does the browser run
>
>  > on the same machine as the application?
>  >
>  > 2. Does you application create network traffic? If so, how many bytes
>  > are transferred to the browser? Each servlet thread will have to wait
>  > until the application has transferred all the data out.
>  >
>  > 3. What kind of disk activity does your application generate? Is it
>  > different when the app is running from the servlet?
>  >
>  > Probably somewhere your servlet threads are sleeping waiting for a
>  > resource. You could do a thread dump to see what is happening (I don't
>
>  > use Windows so I can't remember how you do that with the Win setup)
>  >
>  > In the end, you'll need to profile the system to work out where the
>  > bottlenecks are. You'll need to use network analysers and probably
>  Java
>  > profilers to track down what's happening such as when packets are
>  > received, when the replies are generated and maybe profile what your
>  > app. is doing.
>  >
>  > HTH
>  >
>  > Alan Chaney
>  >
>  >
>  >
>  >
>  > Gilbert, Antoine wrote:
>  >
>  >> Hi
>  >>
>  >>
>  >>
>  >> I have a 2x quad core (8 cpu units) server.
>  >>
>  >>
>  >>
>  >> If I start a java program and this one is launching (at the same
>  time)
>  >>
>  > 8
>  >
>  >> thread doing some CPU intensive jobs, all the CPU are used at 100%,
>  >>
>  > and
>  >
>  >> that's what I'm expecting..
>  >>
>  >>
>  >>
>  >> But, if I am using tomcat, and I call a servlet 8 times to process
>  >>
>  > these
>  >
>  >> 8 jobs, it take longer to execute these same 8 jobs and all the CPU
>  >>
>  > are
>  >
>  >> not used at 100%, it's more like 30%...
>  >>
>  >>
>  >>
>  >> Any idea about this problem or behavior ? I'm using Tomcat 5.5.17,
>  >> windows, JDK 1.6
>  >>
>  >>
>  >>
>  >> Antoine
>  >>
>  >>
>  >>
>  >> !DSPAM:481e1bf27941527717022!
>  >>
>  >>
>  >
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>  >
>
>
>  --
>  David Smith
>  Network Operations Supervisor
>  Department of Entomology
>  Cornell University
>  2132 Comstock Hall
>  Ithaca, NY 14853
>  Phone: (607) 255-9571
>  Fax: (607) 255-0940
>
>
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