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From Tim Bain <tb...@alumni.duke.edu>
Subject Re: Advisory Topic
Date Wed, 23 Sep 2015 13:13:58 GMT
That's definitely possible, if either selectors are in use or the messages
were all sent before any consumer subscribed.  EnqueueCount and
DequeueCount aren't very useful for topics; instead, you need to check the
EnqueueCount and DequeueCount on each individual subscription on the topic,
and for that I always use JMX.  That will eliminate the "messages sent
before the consumer subscribed" factor (because by definition, the
subscription only gets those messages sent after it was created), and using
JMX lets you look at other attributes such as how many messages have been
dispatched, whether a selector is in use, etc.

Many, many people run networks of brokers without the advisory messages
running them out of memory, so it's unlikely that that's your problem.  So
if you see any subscription with messages that have been dispatched but are
not acknowledged, that's a cause for concern; otherwise, this "theory"
isn't your problem and you should focus your attention elsewhere.

With that being said, if you're still on the pre-5.3.0 broker you were on a
month ago, all bets are off (and JMX might or might not expose the
attributes I mentioned).  If you did the upgrade (I sure hope you did, or
that you have one scheduled in the very near future), what version are we
talking about?

Tim

On Tue, Sep 22, 2015 at 9:37 AM, Daniel Israel <disrael@liveops.com> wrote:

>
> We are running a network of brokers, but I'm tracking down a memory issue
> and one of the "theories" is that messages sent to Advisory topics is not
> being freed because we see [sometimes very large] numbers of messages
> enqueued, no messages dequeued, and a non-zero number of consumers.  Is
> that something that's possible?
>
>
>
>
> On 9/21/15, 8:46 PM, "tbain98@gmail.com on behalf of Tim Bain" <
> tbain98@gmail.com on behalf of tbain@alumni.duke.edu> wrote:
>
> >This is the first search result when I Google for 'activemq advisory':
> >http://activemq.apache.org/advisory-message.html
> >
> >If you're not trying to explicitly use advisory topics yourself, you can
> >ignore them; brokers in a network of brokers use them to figure out where
> >consumers are, but you don't have to do anything with them.  If you're not
> >running a network of brokers, you'll get a small performance boost by
> >turning them off, as described on the page I linked.  Note that it's a
> >small benefit and that you'll have to remember to undo the change if you
> >ever move to a network of brokers topology; consider whether it's worth
> the
> >effort for your use case.
> >
> >On Mon, Sep 21, 2015 at 4:44 PM, Daniel Israel <disrael@liveops.com>
> wrote:
> >
> >> I see a large number of advisory topics (ActiveMQ.Advisory.*) in my list
> >> of topics, such as:
> >>
> >> ActiveMQ.Advisory.TempQueue
> >>
> >>
> >> What are these used for?  Is it a problem if these Topics have consumers
> >> and none of the messages are dequeued?
> >>
> >> Thanks for any help.
> >>
>

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