HI Gopal Container never maintains multiple servet instances. I creates only one instance of the servlet, when the first request is executed or u have selected load on start up option. Thereafter only each thread gets executed per request. There was a interface before called as SingleThreadModel which is deprecated now. Some documentation says that when u implement this model, you are guaranteed that no two threads will execute concurrently in the servlet's service method or container may create multiple instances of the servlet where each request is assigned one. There was a whole lot of confusion with this interface as it was a marker interface. Today u must remember one point, there is one and only one instance created for servlet instance.
Let me know if i am wrong or making any sense 2 u.