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Date: Wed, 8 Jan 2014 04:41:40 +0000
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 <CAFitrpRJmuORT7wzh95_41b1McaDcr0grJ+4BNHDim0DQqLz7g@mail.gmail.com>
Subject: Re: Java broker - message grouping in C++ compatibility mode
From: Robbie Gemmell <robbie.gemmell@gmail.com>
To: "users@qpid.apache.org" <users@qpid.apache.org>
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On 8 January 2014 04:33, Helen Kwong <helenkwong@gmail.com> wrote:

> Oh I see, I thought what you meant was that I could only alter the default
> group in shared-groups mode starting with 0.24.


No, I just missed that you said 0.16 and assumed 0.24 was the version you
were using . You could always change it, just in more limited ways in
earlier releases.

To make sure I'm
> understanding this correctly -- changing the the default message group name
> to something else in C++ mode won't change the serial processing behavior I
> saw, right?


Correct


> Messages without a group identifier will still be considered to
> be in a group -- rather than no group -- and they cannot be processed by
> multiple consumers concurrently?
>
>
Yes. In the C++/shared-groups mode every message is considered to be in a
group, it is just a case of whether the message specifies that group or
instead gets put into the default group.


> Thanks,
> Helen
>
>
> On Tue, Jan 7, 2014 at 8:22 PM, Robbie Gemmell <robbie.gemmell@gmail.com
> >wrote:
>
> > I just noticed you said you were using 0.16, somehow glossed over it
> > originally and only noticed the 0.24 in the doc URL (its many hours past
> > time I was asleep, I might be getting tired).
> >
> > Realising that, I should add that prior to 0.22 the only way to alter the
> > default group in the shared-groups mode from 'qpid.no-group' to something
> > else would have been via the 'qpid.default-message-group' queue declare
> > argument when using an AMQP client to create the queue originally, and
> for
> > 0.22 itself only that and the system property approach I mentioned would
> > work.
> >
> > Robbie
> >
> > On 8 January 2014 04:03, Helen Kwong <helenkwong@gmail.com> wrote:
> >
> > > Hi Robbie,
> > >
> > > I see. Thanks for the quick response and explanation!
> > >
> > > Helen
> > >
> > >
> > > On Tue, Jan 7, 2014 at 7:43 PM, Robbie Gemmell <
> robbie.gemmell@gmail.com
> > > >wrote:
> > >
> > > > Hi Helen,
> > > >
> > > > The short answer to your question is that it is the documentation
> which
> > > is
> > > > incorrect, and the behaviour you are seeing is expected.
> > > >
> > > > The long answer is, when that documentation was composed a segment
> was
> > > > missed out indicating this, and needs to be added to the docs. The
> > > > behaviour listed for when no group is specified is only true of the
> > > > 'non-shared' groups supported by the Java broker, in the C++/shared
> > group
> > > > mode any messages recieved without an explicit group value are all
> > > assigned
> > > > to a default group of 'qpid.no-group'. This is as per the behaviour
> of
> > > the
> > > > C++ broker itself, which is explained in the C++ broker docs at the
> end
> > > of
> > > > the following page
> > > >
> > > >
> > >
> >
> http://qpid.apache.org/releases/qpid-0.24/cpp-broker/book/Using-message-groups.html
> > > > .
> > > > For the 0.24 Java broker, this default shared group can be changed
> > > > broker-wide using the Java system property
> > > > 'qpid.broker_default-shared-message-group', or can be overriden for
> an
> > > > individual queue during creation programatically via AMQP clients or
> > the
> > > > management interfaces through use of the argument
> > > > 'qpid.default-message-group' or 'messageGroupDefaultGroup'.
> > > >
> > > > I coincidentally happened to have fixed a defect with the shared
> groups
> > > > functionality last night on trunk. Its not yet included in the
> imminent
> > > > 0.26 release, though I am about to request whether that is possible.
> > > > https://issues.apache.org/jira/browse/QPID-5450
> > > >
> > > > Robbie
> > > >
> > > > On 8 January 2014 02:43, Helen Kwong <helenkwong@gmail.com> wrote:
> > > >
> > > > > Hi,
> > > > >
> > > > > I use the Java broker and client, version 0.16, and am considering
> > > using
> > > > > the message grouping feature (
> > > > >
> > > > >
> > > >
> > >
> >
> http://qpid.apache.org/releases/qpid-0.24/java-broker/book/Java-Broker-Queues.html#Java-Broker-Queues-OtherTypes-Message-Grouping
> > > > > ).
> > > > > From testing I've done, there seems to be a bug with the C++
> > > > compatibility
> > > > > model, and I'm wondering if this is a known issue. Specifically, in
> > my
> > > > test
> > > > > I have a queue configured to use a group header field with
> > > > > "qpid.group_header_key" and C++ mode with "qpid.shared_msg_group",
> > and
> > > > have
> > > > > multiple listeners to the queue. Each listener will sleep for a
> short
> > > > > amount of time when it receives a message before returning. I then
> > > > enqueue
> > > > > 10 messages that do not have a value in the group header field to
> the
> > > > > queue. Since the doc says that messages without a value in the
> > grouping
> > > > > header will be delivered to any available consumer, the behavior I
> > > expect
> > > > > is that the messages will be processed in parallel, i.e., when
> > > listener 1
> > > > > is holding on to a message and sleeping, listener 2 can receive
> > another
> > > > > message from the queue. But what I see is that the messages are
> > > processed
> > > > > serially -- message 2 won't be received by some thread until
> message
> > 1
> > > is
> > > > > done. When I use the default mode instead of C++ mode, then I get
> the
> > > > > parallel processing behavior.
> > > > >
> > > > > Is this is a known bug, and is there a fix for it already?
> > > > >
> > > > > Thanks,
> > > > > Helen
> > > > >
> > > >
> > >
> >
>

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