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From Andrew Miehs <and...@2sheds.de>
Subject Re: Tomcat's scalability
Date Mon, 19 Jun 2006 22:51:11 GMT
Biernatowski Bartosz J wrote:
> I am about 90% sure the bottleneck is Tomcat or what's running on top of
> Tomcat. Application uses JDBC queries to MS SQL server
> Chips are Intel Xeon. My monitoring data: 

Why are you 90% sure?! Your SQL server is running on a seperate machine? 
or the same machine? What does iowait (whatever windows calls it) look 
like? how long do your queries take?


> Memory utilization under 30%, CPU under 10%. Using hardcore performance
> tools and systematic approach. 

Then Tomcat is probably NOT the problem - When Tomcat starts having 
memory problems, etc (not enough) you will see the CPU head up to 100% 
because it spends it whole time doing garbage collection.

Could be anything - the database


> The bottom line is that Tomcat/my application combo don't seem to handle
> more than a certain number of users. All I want to do is to up the # of
> users by 3. 

Well - then you can either buy 3x the databases, 3x the paired tomcat 
servers, etc, etc - (and hope the data doesn't need to be connected). To 
be honest though, this probably won't fix it either.

You say the machine is at 30% CPU. What happens when you get 500 users 
on the machine? Can they still work? Does TC crash? Does everything stop.

 From this description, it sounds like your database the bottleneck, but 
without looking at the application, and what it does, and HOW it tries 
to do it I can't give a better diagnosis.

If this is a REAL problem for your company, look at getting someone in 
to help you and show you how to diagnose this in future.

Andrew

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