[jira] [Created] (WICKET-6356) Clustering failover not working on Tomcat

["wayne pope (JIRA)" <ji...@apache.org>]

wayne pope created WICKET-6356:
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             Summary: Clustering failover not working on Tomcat
                 Key: WICKET-6356
                 URL: https://issues.apache.org/jira/browse/WICKET-6356
             Project: Wicket
          Issue Type: Bug
          Components: wicket
    Affects Versions: 7.5.0, 6.17.0
         Environment: Tomcat 8.0.32, Apache 2.4, OSx and Solaris 9,
            Reporter: wayne pope
         Attachments: IssueFiles.zip

Clustering failover with Tomcat 8 is not working for us in Production. The reason is the following from the debugging that I did and from the best of my understanding:

Whenever a statefull page is used/touched the SessionEntry is updated. This SessionEntry is stored in the tomcats session under the attribute name  "wicket:persistentPageManagerData-APPLICATION_NAME". 
However at the end of the wicket request, Session.internalDetach() is called and setAttribute() is called passing the wicket session under the name "wicket:wicket.hub:session". This triggers the replication in Tomcat (only when setAttribute is called and ONLY that attribute is replicated). Because the SessionEntry is stored under a different attribute name its never replicated.

The only time the SessionEntry is replicated is when a node first starts up and joins the cluster , at this point all sessions are replicated across (including all attritbutes) by the daltamanager and SessionEntry#readObject() is used which contains all the pages. On Tomcat after this initial syncing of all sessions SessionEntry#readObject() is never used.

So the only time session failover works is when you kill the other instance (in a 2 node cluster) just after the other instance starts up - at this point the correct SessionEntry is on the new instance. If however you visit some more pages the new pages are never replicated across as the SessionEntry is never replicated.

Further to this IF the SessionEntry was to be replicated it would not be any good as the cache are transient 
private transient List<IManageablePage> sessionCache;
private transient List<Object> afterReadObject
 
So in summary there seems there is no way for the current mechanism on Tomcat to work. It would seem the SessionEntry.sessionCache needs to be not transient and setAttribute needs to be called for the SessionEntry at the end of request on the internalDetach so that Tomcats deltamanager replicates that attribute in the session.

Attached my quickstart , tomcat, and apache conf.





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