Please forgive me if this is the incorrect place or format for
discussing this. I'm new to trying to develop for Tomcat.
I'm developing a patch for DeltaManager and I'd like to discuss with you
developers if it could be considered for inclusion in the base code.
Please see details below and comment.
Problem: When the "all sessions" message is sent from one node to
another, when the receiving node is first starting up, I often run into
various errors with one of the sessions and it fails to deserialize.
This causes all the remaining sessions in that chunk
(sendAllSessionsSize) to be lost by the receiver. The problem with the
sessions is totally an application problem, but until I can figure those
problems out and solve them I need a way to limit the impact of these
problems to just the one session that is in error. I could set
sendAllSessionsSize="1" but that would take a LONG time to transmit, and
we have many thousands of sessions at any given time.
Change details:
1. Update
org.apache.catalina.ha.session.DeltaManager.deserializeSessions(byte[])
and
org.apache.catalina.ha.session.DeltaSession.doReadObject(ObjectInput)
to produce a more detailed error message when a session is in
error. New error message includes: the session index in the list of
sessions, the session ID, the last field or attribute that was
attempted to be read.
2. Introduce new XML attribute verifySerializedSessions for DeltaManager.
3. If verifySerializedSessions="true",
org.apache.catalina.ha.session.DeltaManager.serializeSessions(Session[])
will first serialize each session then immediately deserialize it.
If all is good, send the session as usual. If any errors are
encountered, create and send a dummy session with a known session ID
instead. (This keeps the session count, which has already been put
in the output stream, correct for the receiving node.)
4. Update
org.apache.catalina.ha.session.DeltaManager.deserializeSessions(byte[])
to discard any received session that has the known dummy session ID.
--
Mitch
