Can any one help me out in creating sessions for each request in java servlets so that until one request completes no other requests will be processed.....

From what your mentioning I do not see any link to actual sessions.

But for your requirement read about synchronized methods in Java and just apply the same to whichever method(service(), doGet(0 or doPost()) you are using to process your requests in the servlet.

Although I think there should be a better way to achieve what you are trying to without restricting your servlet to just service one request at a time.