Hello Guys, I might be asking something that is very fundamental, but please bear with me here. We are using tomcat in a non-clustered environment. We put certain domain objects in the session and we have a heartbeat going which ensures that the sessions are valid in the lifetime of the screen. The domain objects are not serializable. We have randomly seen NullPointerExceptions thrown when accessing properties of these domain objects via the session. I had read about Tomcat deciding to serialize sessions when it thinks that the available memory is getting tight on some forum ( http://www.coderanch.com/t/86379/Tomcat/Problems-disabling-Session-Persistence-Manager) but couldn't see the same in the servlet spec or documentation on tomcat's site. Wanted to verify if this is indeed the case? If yes, under what (approximate) conditions does tomcat decide to serialize sessions to disk and back? Overall, is the recommended approach to always make objects in the session serializable? Also, wouldn't it be great if a better exception like NotSerializableException be thrown rather than the user stumbling over null values and NPE's being thrown?
Thanks in advance! P.S.: We are using tomcat 6.0.16 on Solaris in 64 bit JVM mode with Xms 1024m and Xmx 4096m.
