I am doing an asp.net project. In this i blocked user log in, meant's if a user logged in one system or browser he can't log in in other browser or system.
Now the problem is i want to free resources if the user directly closing the browser of shutdown the system.
Your description is somewhat vague on 'how you block the user'. Nevertheless: Http is a stateless protocoll and you are not able to tell if a browser window is open or not.
You can manipulate this behaviour be setting the session timeout lower. You can set a session cookie, which expires at the end of the session.
Alternativly there is a javascript snippet here, that imitates this behaviour. Scroll down a little bit to get the snippet.
