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From Peter Crowther <>
Subject RE: Tomcat Concurrent Requests
Date Mon, 01 Jun 2009 14:58:38 GMT
> From: CrystalCracker []
> The 5 seconds calls are all database or webservice calls. So
> they all go to waiting state.

OK.  So the bottleneck almost certainly isn't Tomcat.

> I did some load tests using JMeter, but I had problems coming to a
> conclusion with the data. What should I look for exactly? Because as I
> increase the no of concurrent requests, the app starts
> responding slower and slower.

1) Make sure you're measuring the important things.  You should be measuring load on Tomcat,
but also on the database and on the web services - and on the network!

2) Look for the bottleneck.  It may be in an odd place - RAM or (equivalently, in many cases)
disk seeks per second on the database server are both common bottlenecks.  There's no guarantee
it's on your Web server at all (though it might be).

JMeter's output isn't useful for finding bottlenecks.  The output of tools on your servers
*is* useful.  On Windows, Performance Monitor is your friend.  On UNIX, vmstat and iostat
are good first lines of attack; your flavour of UNIX probably has better tools than those.

                - Peter

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