Re: Camel, concurrent consumers, message groups and prefetch size

[Paul Gale <pa...@gmail.com>]

claus.takeLeafFrom(christian.getBook());


:)


On Mon, Mar 31, 2014 at 5:09 PM, Christian Posta
<ch...@gmail.com>wrote:

> On Fri, Mar 28, 2014 at 10:06 AM, Paul Gale <pa...@gmail.com> wrote:
> > Hi,
> >
> > I have an embedded Camel client that contains a single route. All
> messages
> > the route consumes have their JMSXGroupID property set.
> >
> > What I need to know is how message grouping behaves in the context of
> > concurrent consumers and how does the choice of the prefetch buffer size
> > come into play (when not using the default)?
>
> It's the same as if not using concurrent consumers, as described on
> the ActiveMQ wiki... however,
> each one of your consumers will compete for its own individual message
> group.
>
> >
> > Say I have route that looks like:
> >
> >
> from("activemq:some_queue?concurrentConsumers=5&maxConcurrentConsumers=5&destination.consumer.prefetchSize=5")
> >   .bean(new SomeBean());
> >
> > - Is it guaranteed that a given message group will always be handled by
> the
> > same consumer thread?
> Same logical thread, yes. The same consumer will consume the messages
> for which group it's assigned up until the group closes or the
> consumer is closed.
>
> >
> > - Is the prefetch size applied at the consumer thread level or to the
> > single underlying connection that they're all sharing?
>
> It's applied at the individual consumer, not at the connection.
>
> >
> > - If the prefetch size is applied at the connection level, is it correct
> to
> > assume that its value must be >= the number of concurrent consumers to
> > avoid leaving threads idle when there are messages available to be
> > processed, example: when consumer.prefetchSize=1?
> >
> > Yes, I have read this page:
> > https://camel.apache.org/parallel-processing-and-ordering.html but it
> > didn't answer my questions.
> >
> > Thanks,
> > Paul
>
>
>
> --
> Christian Posta
> http://www.christianposta.com/blog
> twitter: @christianposta
>