Re: Cluster error when starting up web application

[Aadi Deshpande]

Upon further research, it seems that DeltaSession.setId() fires the 
sessionCreated events to registered listeners, but this happens before a 
session is declared valid ( i.e. setValid(true) has not been called ).

so when a  registered listener tries to utilize ( what it seems to 
believe is ) a newly created session, the setAttribute method throws the 
IllegalStateException..

Now I don't know too much about how the actual workings of the 
HttpSession should go, but in my opinion, the sessionCreated events 
should not be fired unless a valid session has been created.  which 
seems to imply that maybe setValid() should doing the firing...

However, that doesn't sit well with me since it doesn't make sense for a 
session to be truly valid unless it has a sessionId, which either
forces there to be an implict order between setId() and setValid() which 
is no good, requiring that either/or check to see if the other has been 
truly satisfied, and setting up some sort of implicit sequence coupling.

the alternative, as I see it, is move the tellNew() invocation to the 
DeltaManager ( it's declared public, so it's already exposed ).

I tried that, by patching up the TC5 sources and it seemed to resolve 
the issue.

Again, as I know little to nothing of how sessions should work and what 
other implications this refactoring may have, what should be my next 
course of action?

Should I contact the webwork people? Is this not correct use of sessions 
and session listeners?

Should I open up a bug and/or propose my patch?

Thanks in advance for reading and/or responding,

-a





Aadi Deshpande wrote:

Hi,

I just got Tomcat 5.0.19 and after setting up the new delta based 
cluster manager, i get this during the startup my application :

SEVERE: Session event listener threw exception
java.lang.IllegalStateException: setAttribute: Session already 
invalidated
       at 
org.apache.catalina.cluster.session.DeltaSession.setAttribute(DeltaSession.java:1306) 

       at 
org.apache.catalina.cluster.session.DeltaSession.setAttribute(DeltaSession.java:1283) 

       at 
org.apache.catalina.cluster.session.DeltaSessionFacade.setAttribute(DeltaSessionFacade.java:17 

7)
       at 
com.opensymphony.webwork.lifecycle.SessionLifecycleListener.sessionCreated(SessionLifecycleLis 

tener.java:50)
       at 
org.apache.catalina.cluster.session.DeltaSession.tellNew(DeltaSession.java:459) 

       at 
org.apache.catalina.cluster.session.DeltaSession.setId(DeltaSession.java:431) 

       at 
org.apache.catalina.cluster.session.DeltaManager.createSession(DeltaManager.java:377) 

       at 
org.apache.catalina.cluster.session.DeltaManager.messageReceived(DeltaManager.java:895) 

       at 
org.apache.catalina.cluster.session.DeltaManager.messageDataReceived(DeltaManager.java:794) 

       at 
org.apache.catalina.cluster.tcp.SimpleTcpCluster.messageDataReceived(SimpleTcpCluster.java:561 

)
       at 
org.apache.catalina.cluster.io.ObjectReader.execute(ObjectReader.java:117) 

       at 
org.apache.catalina.cluster.tcp.TcpReplicationThread.drainChannel(TcpReplicationThread.java:17 

6)
       at 
org.apache.catalina.cluster.tcp.TcpReplicationThread.run(TcpReplicationThread.java:114) 



As far as I can tell, it's happening when I request a page that has 
the webwork2 RequestLifecycleFilter set for that url pattern.  The 
doFilter function creates a HttpSession if none exists, which I assume 
calls the SessionLifecycleListener.sessionCreated(), but for some 
reason, it seems like the session is being invalidated prematurely..

Here's the relevant piece from my web.xml :
   <filter>
       <filter-name>container</filter-name>
       <filter-class>
           
com.opensymphony.webwork.lifecycle.RequestLifecycleFilter</filter-class>
   </filter>
   <filter-mapping>
       <filter-name>container</filter-name>
       <url-pattern>/*</url-pattern>
       <!-- modify appropriately -->
   </filter-mapping>
   <listener>
       <listener-class>
           
com.opensymphony.webwork.lifecycle.SessionLifecycleListener</listener-class> 

   </listener>
   <listener>
       <listener-class>
           
com.opensymphony.webwork.lifecycle.ApplicationLifecycleListener</listener-class> 

   </listener>

and from my server.xml file, taken pretty much verbatim from the 
default server.xml:

   <Cluster className="org.apache.catalina.cluster.tcp.SimpleTcpCluster"
                
managerClassName="org.apache.catalina.cluster.session.DeltaManager"
                expireSessionsOnShutdown="false"
                useDirtyFlag="true">

           <Membership
               className="org.apache.catalina.cluster.mcast.McastService"
               mcastAddr="224.64.64.128"
               mcastPort="45600"
               mcastFrequency="500"
               mcastDropTime="3000"/>
    <Receiver
               
className="org.apache.catalina.cluster.tcp.ReplicationListener"
               tcpListenAddress="auto"
               tcpListenPort="4060"
               tcpSelectorTimeout="100"
               tcpThreadCount="3"/>

           <Sender
               
className="org.apache.catalina.cluster.tcp.ReplicationTransmitter"
               replicationMode="pooled"/>

        <Valve 
className="org.apache.catalina.cluster.tcp.ReplicationValve"
              filter=".*\.gif;.*\.js;.*\.jpg;.*\.htm;.*\.html;.*\.txt;"/>

       </Cluster>

Anyone know what's going on? Or can provide some insight into what I 
may be missing?

Thanks for any info.

-a

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