Hi santosh,
advantages/disadvantages of Tomcat in contrast to what alternatives? I think it's hard to give a good answer to this question without knowing more details. Tomcat probably doesn't give you the same performance like Apache for example when you have static HTML contents. But that depends on your application of course. Also there are a lot more aspects you have to consider like clustering, load-balancing, session handling in a cluster and many more. For this reason it's not as easy as it may seem to gain more performance by simply substituting one server product with another. If you're talking about really heavy traffic there's often no other way to go than clustering multiple servers and then the overall performance depends on a lot of other factors besides the web server product. If you have an application which doesn't scale well in a clustered environment that could be your bottleneck and it wouldn't matter which server you're using. If your application relies a lot on database access the database server(s) could be a bottleneck as well.
Besides these points there are even more aspects to consider when running web applications under heavy load. Unfortunately it's not possible to give really good advices without knowing the exact requirements of the software, what "heavy" load means for you etc.
I've seen web applications in production use which worked really fine on a single server with 20-25 requests per second (which is surely not really heavy load). In this situation it was enough to have slightly more users and everything broke down with about 30 req./s.
So the best way could be to simply
test your application before launching it for production use! Make an estimation how many users/request you could probably expect and then stress test your application! This will show you where the bottlenecks are and you can still think about optimization where it's really needed!
Marco
[ November 15, 2008: Message edited by: Marco Ehrentreich ]
[ November 15, 2008: Message edited by: Marco Ehrentreich ]