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From Dejan Bosanac <de...@nighttale.net>
Subject Re: Automatic recovery when using Message Groups
Date Thu, 12 Feb 2009 18:05:03 GMT
I've filed a Jira enhacement request for this
https://issues.apache.org/activemq/browse/AMQ-2106

Cheers
--
Dejan Bosanac

Open Source Integration - http://fusesource.com/
ActiveMQ in Action - http://www.manning.com/snyder/
Blog - http://www.nighttale.net


On Thu, Feb 12, 2009 at 6:12 PM, kalki70 <lrg@pobox.com> wrote:

>
> Hi, Dejan,
>
> I agree consumers don't know which groups they will be assigned. As you
> said, if a consumer goes down, other will take those groups, but the
> problem
> comes when the consumer that went down comes back again. It will never
> receive any more messages. So what I proposed was something like the
> consumer saying :
> "Hey, I crashed, but I came back. Give me back the message groups I had
> before. By the way, last time I subscribed my consumer id was xxxxx".
>
> The feature you mention, that when a new consumer subscribes, the broker
> tries to distribute evenly the messages groups, is just like having now my
> Christmas gift :jumping:. It would be really wonderful :clap:, because it
> solves the problem of adding more consumers dynamically.
>
> The policy using consumersBeforeDispatchStarts and timeBeforeDispatchStarts
> seemed to me just a temporary solution to the problem, but this one looks
> much more powerful. Not only consumers that go down can come back and
> process messages, also more consumers can be added at any time.
>
> Best regards,
>
> Luis
>
> Dejan Bosanac wrote:
> >
> > Hi Luis,
> >
> > I'm not sure this is the correct use case. Consumers don't explicitly
> know
> > what groups they will be assigned to when they first subscribe, so there
> > is
> > usually no difference what consumer is consuming messages from what
> group.
> > When your consumer goes down, the other one will take its group and
> > everything will work fine.
> >
> > Maybe we should add a feature that would instruct the broker to try to
> > make
> > an even distribution of groups among consumers. So when the new consumer
> > is
> > subscribed, the broker will see if it can reassign certain groups to it
> > depending on the number of groups assigned to existing consumers. I have
> > an
> > impression, that this would make for you as well?
> >
> > Cheers
> > --
> > Dejan Bosanac
> >
> > Open Source Integration - http://fusesource.com/
> > ActiveMQ in Action - http://www.manning.com/snyder/
> > Blog - http://www.nighttale.net
> >
>
> --
> View this message in context:
> http://www.nabble.com/Automatic-recovery-when-using-Message-Groups-tp21938109p21980479.html
> Sent from the ActiveMQ - User mailing list archive at Nabble.com.
>
>

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