This week's book giveaway is in the OO, Patterns, UML and Refactoring forum. We're giving away four copies of Refactoring for Software Design Smells: Managing Technical Debt and have Girish Suryanarayana, Ganesh Samarthyam & Tushar Sharma on-line! See this thread for details.
Due to the basic structure of Java, you are never going to be able to get the in-memory size of a session. If all of your session storage objects are serializable, you could write the session to a file or a ByteArrayOutputStream and see how large the serialized form is. Bill