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From "Sai Bobba" <>
Subject Tomcat causing high CPU load
Date Mon, 05 Nov 2007 01:25:46 GMT

I'm using the following:

Tomcat 6
SQL Server 2000
Server running on Windows 2000

The web app deployed consists of: an application form filled in by the
prospective student, a servlet that gets the form parameters
(>60), processes them, and saves the data input by the user to several
tables in the database.  Processing of the form data involves applying
testing the data against admission criteria.
When the web ap was first deployed some months ago, we had the problem that
some of the input by the users was too large for the space allocated in the
corresponding column in the db table - this caused SQLExceptions to be
thrown each time this happened. At the same time we noticed that many times
a day the CPU load on the server machine was up at 60% - 90+% - Tomcat was
responsible for this CPU load almost exclusively - the other processes
running on the machine were taking <3%. This meant having to restart Tomcat
several times a day. At first we thought this was related to the db
insertion problem. We fixed the db issue so that no more exceptions are
thrown, but we still find the CPU load up at >60% at least once a day -
Tomcat responsible again.
Another thing I noticed in testing the app was that if after I submitted an
application I hit the 'Back' button on the browser and then submitted again,
app would hang, and the CPU load on the server machine would rise to >60%. I
tried this several times, with the same result each time. However, it was
possible to submit an aplication from a different browser even when the CPU
load was high. Oddly, when I did this test on my local machine I didn't have
this problem.
I hope I've laid out the situation clearly. My searches on the web for this
sort of problem have yielded no solution.
If anybody has had this problem and fixed it, or has an insight into what
the problem might be, I'd greatly appreciate hearing about it!

Many thanks!


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