web instance already stopped

seems like i was creating instance of something which was already created..i removed the instance and now it works fine

This because of you are deploying new instance of your application to server but the some thread or connection of previous instance attempts doing some business logic you have written. That's why, the main part of JVM called ClassLoader informs you about "Illegal access: this web application instance has been stopped already" and throws appropriate exception ... You can switch off auto deploy feature of Application Server which preferable on Production Environment and after deploying application restart server manually. Or you can in Class level control Servlet Life Cycle :))) during "pre deploy" close all connection or stop some threads. Or use sophisticated way controlling Threads with ManagedExecutorService. Good luck!!!