Hi, Please keep the mails on the list so that everybody can share the discussion.
On Thu, 2003-08-14 at 21:30, Barlow, Dustin wrote: > I guess it isn't obvious to me why is "readahead" important in terms of > efficiency of queue message consumption. Can you elaborate? > The readahead means the ConnectionConsumer can get the next message(s) while you process the current one(s). It only has to wait for a session to become available to process those messages. > Is it possible to configure the container to wait for the ServerSession in > this case? I have already defined a separate invoker-binding and a > container-config for this bean, so I could isolate it to just the singleton > MDB. > It is not supported with the current implementation. It could be supported with the changes I mentioned to the ConnectionConsumer, but this wouldn't be portable to other JMS implementations and see below. > I am not sure that having it wait for the ServerSession and then consume the > message would solve the problem. If the retry behaviour of the container is > simply consuming the message and then pushing the message back onto the > source queue again, this still wouldn't guarantee that other messages > wouldn't be in front of that reposted message correct? > It wouldn't guarantee it, the message is put back at the top of the queue - but higher priority messages could have arrived in the mean time. This problem and the no guarantee of ordering for MDBs (because of the concurrent sessionpool) is mentioned in the spec. JBoss lets you avoid the concurrency problem but not the ordering problem of redelivery. The actual ordering is message priority then arrival order (the initial arrival not the nack). Regards, Adrian > Thanks for the help, > > Dustin > > > > -----Original Message----- > From: Adrian Brock > To: [EMAIL PROTECTED] > Sent: 8/14/2003 3:11 PM > Subject: Re: [JBoss-user] MDB Singleton retry semantics > > That isn't the way it currently works. > > The ConnectorConsumer immediatley retrieves the next message > from the queue then waits for a ServerSession from the pool. > > Once you've nacked the failed message back into the queue, it will > process the waiting message using the freed session. > > It will then ask the queue for the next message which will > be the one you nacked. > > To make it work the way you want the ConnectionConsumer > would have to work in the opposite order. > Instead of receiving message(s) and waiting for a > ServerSession. It would wait for a ServerSession then > receive the message. > This is obviously less efficient in the normal use case, > you lose the "readahead" of the messages. > > Regards, > Adrian > > On Thu, 2003-08-14 at 19:00, Barlow, Dustin wrote: > > I have a singleton CMT MDB consuming on a JMS queue with a retry > threshold > > set to 3 attempts. I made the assumption that no other messages on > the > > queue would be consumed until the current message being processed > either > > finishes and is consumed, or in the event of a container transaction > > rollback and the retry threshold is reached, the message is consumed > off the > > source queue and pushed to the DLQ. > > > > However, the behaviour I'm seeing is that on the retry, other messages > > sitting on the queue are consumed prior to the retry occurring. The > > singleton is working in terms of only one message at a time being > processed, > > however the retry semantic seems odd to me in that it appears like the > > implementation of the retry logic is just simply pushing the message > back on > > the queue to be consumed again in a different "thread" later on. > > > > Is this correct? If so, how do I change that behaviour so that no > other > > messages on the queue are triggered until the message completes its > > processing either by consumed normally, or by being consumed and > pushed to > > the DLQ once the retry threshold is reached? > > > > Dustin > > > > > > ------------------------------------------------------- > > This SF.Net email sponsored by: Free pre-built ASP.NET sites including > > Data Reports, E-commerce, Portals, and Forums are available now. > > Download today and enter to win an XBOX or Visual Studio .NET. > > > http://aspnet.click-url.com/go/psa00100003ave/direct;at.aspnet_072303_01 > /01 > > _______________________________________________ > > JBoss-user mailing list > > [EMAIL PROTECTED] > > https://lists.sourceforge.net/lists/listinfo/jboss-user ------------------------------------------------------- This SF.Net email sponsored by: Free pre-built ASP.NET sites including Data Reports, E-commerce, Portals, and Forums are available now. Download today and enter to win an XBOX or Visual Studio .NET. http://aspnet.click-url.com/go/psa00100003ave/direct;at.aspnet_072303_01/01 _______________________________________________ JBoss-user mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/jboss-user
