I am willing to host an application in a single machine with out any fail-over or load balancing at the hardware level as per my budget.
But, to my knowledge, as the no of hits increases to the tomcat, it has a drawback of going down. So, to get rid of that I want to go with multiple instances for the same application. So to do so, which load balancer would be better either mod_jk or mod_proxy. You can even suggest any other open source tool that helps me in load balancing the application hits.
My application contains structs and not even springs and my OS is rhel 6.x. Please suggest according to the good performance also.
Thanks in advance.
Running multiple instances of one application on the same machine only leads to the application sharing the resources - minus the overhead for the additional Tomcat instances and the loadbalancer.
This is pretty much the same as dividing cargo on individual tires because a car gets slow when it is too loaded. Staying in the picture: what you want is a turbocharger.
Translated that would be a reverse proxy cache.
I'd suggest using varnish. You can configure it to serve static resources like images and stylesheets from RAM after they were delivered the first time, reducing the requests passed to your application drastically.
It may be configured as a classical load balancer, too.