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From David Smith <d...@cornell.edu>
Subject Re: Tomcat problem on a multiple CPU system
Date Mon, 05 May 2008 02:59:51 GMT
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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