if our application is having potential of getting thousands of concurrent requests, can we go with struts2 ? i am scared because by default struts creates new instance for new request. also i don't want single instance to handle all the request with threads .
There is no reason to expect Struts cannot handle thousands of concurrent requests. Creating Action instances is probably the least of your performance worries. You'll need enterprise-level hardware for both your application and database server (probably more than one per), a very fast network, an efficient design and so on. Our EnterprisePerformance FAQ is a good place to start.