Apache HTTP Server/Tomcat Load Balancing Problem

I am trying to load balance our web based application using Apache HTTP Server and Tomcat on Linux.

I think I have setup the environments correctly, although I am not sure of the configuration parameters for either apache or tomcat. We have apache running on one linux server and 2 instances of tomcat running on two nodes with linux installed.

I am using JMeter to test the load on our app. I can get JMeter to send 30 simultanous requests (num of users)  for 4 consecutive intervals in each thread group, however as I change the number of users to 35, I start getting
"HTTP response code: 500
HTTP response message: Internal Server Error" errors.

As I monitor apache's log file, I can see it is receiving all the POST requests, however it seems to me like it is not able to send them all to its workers, tomcat1 and tomcat2, or workers are not capable of accepting and serving these requests.

If you have any suggestions/recommendations on how to configure apache or tomcat to handle more simultanous users, please advise.

I am using:
apache 2.2
mod_jk: download   mod_jk-1.2.21-apache-2.2.x-linux-i686.so
tomcat 5.5.12
jrockit r27

Thank you,
Noushin
NoushinBAsked:
Who is Participating?
I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

Mayank SAssociate Director - Product EngineeringCommented:
Are there any error logs in Tomcat's logs? 500 internal error would mean some exception was thrown on the server side. Are you closing your connections, etc properly in finally blocks? Also ensure you don't store any state in the servlets and if you do then they should be thread safe. Difficult to say what it is without knowing what your application does.
0
NoushinBAuthor Commented:
After turning on exception handling, we noticed our calls to web services were timing out. We increased our WS timeout setting and the application proceeded successfully. Thanx.
0
Mayank SAssociate Director - Product EngineeringCommented:
Yes that is why Tomcat was getting those time out exceptions and showing you a 500 ;)
0

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
Computer101Commented:
Forced accept.

Computer101
EE Admin
0
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
Web Servers

From novice to tech pro — start learning today.