[jbossseam-issues] [JBoss JIRA] Commented: (JBSEAM-2888) Calling Session.invalidate() leads to an explosion of new sessions

[Dan Allen (JIRA)]

    [ http://jira.jboss.com/jira/browse/JBSEAM-2888?page=comments#action_12409858 ] 
            
Dan Allen commented on JBSEAM-2888:
-----------------------------------

After some research, I have reached the root of the problem. First, this only happens when you deploy to Tomcat (I tested the Tomcat 6.0.X series). The problem occurs when you invoke the method binding expression #{session.invalidate} from a UI command button. Although Seam has a component named "session", the session that is actually resolved is the org.apache.catalina.session.StandardSessionFacade, the implementation of HttpSession. Seam yells at you not to interact with invalidate() method on this API directly. The proper way to invalidate the session would be to call #{org.jboss.seam.web.session.invalidate}.

I verified that the explosion of sessions occurs using the Tomcat JPA example under the examples directory. <s:link action="#{session.invalidate}" value="Invalidate Session (with HttpSession)"/>. The problem does not occur when using <s:link action="#{org.jboss.seam.web.session.invalidate}" value="Invalidate Session (with Seam)"/>

I don't understand why this happens on Tomcat and not JBoss AS. Theoretically, there is nothing we can do about it since we cannot stop the HttpSession#invalidate() method from being invoked. Perhaps a better solution is to use a different name (or alias) for the Seam session wrapper so that people don't mistakenly think they are using it when in fact they are interacting with the implicit session EL variable.

> Calling Session.invalidate() leads to an explosion of new sessions
> ------------------------------------------------------------------
>
>                 Key: JBSEAM-2888
>                 URL: http://jira.jboss.com/jira/browse/JBSEAM-2888
>             Project: Seam
>          Issue Type: Bug
>          Components: Core
>    Affects Versions: 2.1.0.A1, 2.0.2.CR1, 2.0.1.GA
>            Reporter: Dan Allen
>         Assigned To: Norman Richards
>             Fix For: 2.0.2.CR2, 2.1.0.BETA1
>
>   Original Estimate: 2 days
>  Remaining Estimate: 2 days
>
> There appears to be a pretty nasty bug in Seam during the post-session invalidation routine. If you call #{session.invalidate} (which is also called by #{identity.logout}) a new session is created each time the conversation is referenced for the duration of the request.
> To observe this behavior, install an HttpSessionListener that watches for session creation. Then run one of these two action listener methods. You will observe the many hits to the sessionCreated() method during the request that terminates the session with Session.invalidate().
> public class SessionNotifier implements HttpSessionListener {
>     public void sessionCreated(HttpSessionEvent e) {
>         System.out.println("created session with id: " + e.getSession().getId());
>     }
>     public void sessionDestroyed(HttpSessionEvent e) {}
> }
> You can run Thread.dumpStack() in the listener to see that it is happening as a result of attribute reads on the ServerConversationContext. I guess because the session was invalidated, Seam attempts to recreate the session over and over as it works with the conversation within that request.
> I consider this a pretty serious bug because it leads to significant growth of the HTTP session.

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