Mailing-List: contact users-help@activemq.apache.org; run by ezmlm
Precedence: bulk
Reply-To: users@activemq.apache.org
Received-SPF: pass (herse.apache.org: domain of james.strachan@gmail.com
 designates 66.249.82.224 as permitted sender)
DomainKey-Signature: a=rsa-sha1; c=nofws;
        d=gmail.com; s=beta;
        h=received:message-id:date:from:to:subject:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references;
        b=ff+QD2PRrnySdRDP/NL4blomcaI/rDM/PztkpL5FU8pm8tn48R5IDBQQdLdjwOW+hlhlnhh7wnV6JnIBgn4N+nDmiXysOsB3JK+d1j30bJHpeg4Gn/9AKptdPDvLMemx8ZxQIbjmL58IxJWkJ+Z4KP1AtUvzNwfUzF/xqsGvTPk=
Message-ID: <ec6e67fd0706191051l2acc225er8b89a75d81e186af@mail.gmail.com>
Date: Tue, 19 Jun 2007 18:51:44 +0100
From: "James Strachan" <james.strachan@gmail.com>
To: users@activemq.apache.org
Subject: Re: Problem with message groups
In-Reply-To: <11191679.post@talk.nabble.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
Content-Disposition: inline
References: <11178578.post@talk.nabble.com>
	 <ec6e67fd0706182059x3d392ce2l2081c4e42e118b2f@mail.gmail.com>
	 <11191679.post@talk.nabble.com>

On 6/19/07, jcm231 <jcordoba@dynasty.es> wrote:
>
>
>
> James.Strachan wrote:
> >
> > On 6/18/07, jcm231 <jcordoba@dynasty.es> wrote:
> >>
> >> Hi!
> >>
> >> I am have a standalone ActiveMQ server and I am sending messages using a
> >> producer. The messages include the JMSXGroupID header with two different
> >> values: "one" and "two". I launch two Consumer objects, both being
> >> threads
> >> and implementing the interface MesageListener. The result is that only
> >> one
> >> of the two consumers receives all the messages. Sometimes is the first
> >> consumer and sometimes is the second who receives them all.
> >>
> >> What am I doing wrong? It is the first time I use ActiveMQ and I would
> >> thank
> >> any help anybody could give me.
> >
> > We don't yet guarrentee an exact round-robin dispatch policy on a per
> > message group basis; consumers tend to eagerly grab as many messages
> > as will fit into their pre-fetch buffer.
> > http://activemq.apache.org/what-is-the-prefetch-limit-for.html
> >
> > to mimick round-robin, try setting the prefetch to 1 on both
> > consumers; or try using thousands of messages
> >
> >
> >
> >
> > --
> > James
> > -------
> > http://macstrac.blogspot.com/
> >
> >
>
>
> I have sent 34000 messages but they all get consumed by the same consumer.
>
>
> I tried to specify the prefetchSize as indicated in:
>
> http://activemq.apache.org/what-is-the-prefetch-limit-for.html
>
> but I am not creating the ActiveMQQueue on the consumer's code but on the
> xml file. So I put this on my activemq.xml file:
>
>
>   <!-- Destination -->
>   <bean id="destination" class="org.apache.activemq.command.ActiveMQQueue">
>     <constructor-arg>
>
> <value>example.MyQueue?consumer.prefetchSize=1;consumer.exclusive=false</value>
>     </constructor-arg>
>   </bean>
>
> but it seems not be effective.

Creating a queue does nothing, unless you actually use it in your JMS
client (e.g. to consume from)

If you're struggling to set the prefetch groups; try sending say
50,000 messages to group 1, then start mixing 1 and 2; then the first
consumer will get its pre-fetch buffer filled with the first group; so
it won't grab group 2. (Or have lots of groups)

-- 
James
-------
http://macstrac.blogspot.com/