HTTP connector running out of processors under heavy load - our solution

["Karau, Joe" <Jo...@Kingland.com>]

In no way am I trying to say that this is the final solution to the
referenced problem, but just thought I'd share what we encountered in
relation to the referenced bug.
Bug ID: 5735 
http://issues.apache.org/bugzilla/show_bug.cgi?id=5735
Short version: Using the client VM instead of the server VM seemed to
alleviate the symptoms we were encountering.
Longer version:
Recently we had been running into a problem with symptoms similar to the
reported bug referenced above.  We'd run the application, under
(relatively) heavy and sometimes not so heavy load, at times the
connectors would appear to stop responding.  Tomcat was still up and
running, plenty of processor and memory was still available, but
requests would no longer be answered by Tomcat.  We would take away the
load, and Tomcat would still not respond.
We tried Tomcat 4.1.30 & Tomcat 5.5.6 (I know not the latest, but that
is what we had regressed our app on).  Running on both a single and
multi-processor Windows machine.  The Sun's JDK version was 1.4.2.
Finally, I noticed that we were using the server VM instead of the
client.  We switched it to the client, and our problems seemed to
disappear.  I know that this solution doesn't make much sense because
the VM's should be functionally identical, but we were able to increase
the number of concurrent users we could support by +600% after the
switch.

thanks

Joseph Karau 
Kingland Systems 
joe.karau@kingland.com 
507-536-3629 
AIM: jkarau3629 



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