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From "Peter Crowther" <Peter.Crowt...@melandra.com>
Subject RE: How to increase Tomcat webserver speed?
Date Fri, 05 Oct 2007 08:44:12 GMT
> From: David Delbecq [mailto:delbd+jakarta@oma.be] 
> Since you say CPU usage on your machine is around 5% during 
> those tests, 
> and your database is on same machine as tomcat server,  i doubt the 
> bottleneck really is on database.

The OP never reported on disk I/O - this is often the killer on database
speed, and "80g HDD" to me suggests there's a single, fairly
slow-spinning drive in the box.

> The first ting i'll suggeste is to 
> take all queries run by your application, make an sql script of them, 
> and run this script using a mysql client. If the script 
> returns in less 
> than a second, it's your application the bottleneck at some 
> point. If it 
> takes 10 seconds, improve your database designs, add indexes, reduce 
> queries.

Agree.  Also check the disk I/O load - I didn't see which operating
system the OP is running, but check Physical Disk / Average Disk Queue
Length on Windows (in the Performance tool) or use "vmstat" on most
UNIXes to get a rough-and-ready feel for the disk traffic.

I'm not saying it *is* the problem, but I've seen far too many systems
where disk ends up being the bottleneck!  See "Amdahl's Rule of Thumb"
near the bottom of http://en.wikipedia.org/wiki/Amdahl's_law - a
balanced system needs 1 byte of RAM and 1 bit per second of I/O for each
instruction/second the CPU can run.  These days, the CPUs run 10^9
instructions per second, we have 10^9 bytes of RAM in a system, but most
physical disks peak at around 10^8 bits/s of I/O, or under 10^7 if
they're subject to heavy random access (say by a database).  It's not
enough!

		- Peter

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