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From "Kevin Williams" <>
Subject RE: tomcat CPU utilization CPU only 50%
Date Mon, 07 Feb 2005 17:58:21 GMT

Thanks all for the help.  I further optimized the environment while
troubleshooting.  In case anyone else is in a similar issue, I'll list
the solution that worked for me--turn off hyperthreading.  The two Xeon
CPU's are hyperthreaded to represent 4 CPU's on the machine.  I'm not
sure exactly how tomcat/java interact with this, but it was not
favorable.  A coworker mentioned that the windows performance monitor
often records total CPU utilization incorrectly due to the logical split
of the CPU's acting as 4 instead of 2.  Disabling the hyperthreading in
the system bios shot the CPU utilization up to 70%-90% (I imagine the
other 10% of CPU is being reserved by other applications).

Thanks again for the help,

Kevin Williams

-----Original Message-----
From: news [] On Behalf Of Vic
Sent: Thursday, February 03, 2005 9:09 PM
Subject: Re: tomcat CPU utilization CPU only 50%
Importance: Low

You could be DB bound or LAN bound.
What is the switch telling you LAN utilization is?
What is the DB stress test telling you?

Kevin Williams wrote:

>I am trying to performance test an application running Tomcat with
>Apache w/SSL (connected using mod_proxy).  The OS is Windows Server
>The test I am running is simulating a user logging into the application
>(using JMeter for the testing framework).  Increasing the number of
>users from 1, 2, 3, 4,5 the total CPU utilization jumps considerably.
>After 5 users the CPU utilization hits 50% for a second and then
>drops...When simulating 10 users, the CPU hits50% for a few seconds and
>drops back down, the more users, the longer the CPU is pegged at 50%.
>My question is why is tomcat only using 50% of the CPU?  Seeing the CPU
>grow significantly with each user, and then peg out for longer periods
>of time with an increased user load indicates that the CPU is the choke
>point.  Using performance monitor, the Tomcat % Processor Time pegs out
>at 100% for the duration that total CPU utilization is at 50%.  Is
>a configuration option that I am unaware of to allow tomcat to use more
>Thanks in advance!

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