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Subject: Re: InFlightCount/DispatchCount meaning
From: Denis Bazhenov <bazhenov@farpost.com>
To: users@activemq.apache.org
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Date: Thu, 25 Jun 2009 11:35:32 +1100
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Yeah, but I have fast consumers and slow producers. In my case
InFlightCount must be about zero, I guess. This is because of producers
too slow to generate a lot of messages for consumers. Do I miss
something?

On Wed, 2009-06-24 at 17:00 +0100, Gary Tully wrote:
> the inflight count means inflight to a consumers session, not necessarily
> received and unacked by a consumer. You must have 6 consumers. There is an
> additional prefetch extension that is used in transactions when a message is
> delivered so that a transction can span the prefetch limit.
> 
> 2009/6/24 Denis Bazhenov <bazhenov@farpost.com>
> 
> > There is one more aspect that I don't understand.
> >
> > My queue InFlightCount value vary about 6000. One moment it's exactly
> > 6000, another moment it's 6012 and so on (but never <6000). So new
> > messages are acknowledged correctly, but there is 6K messages that were
> > not commited by consumer, I guess.
> >
> > We have 2 options here. First of all maybe these 6K messages were
> > dispatched to another consumer (and acknowledged), so InFlightCount must
> > be equals zero. Second option is that these 6K messages are not
> > dispatched to another consumer and hang up somewhere.
> >
> > Where is truth?
> >
> > P.S. Browse method on queue (via JMX console) says that queue doesn't
> > have messages.
> >
> > On Tue, 2009-06-23 at 16:51 +0100, Gary Tully wrote:
> > > the prefetch has a large bearing on this, it defaults to 1000 for queues.
> > >
> > > If you have lots of consumers that consume just a few messages (say 100),
> > > each will get dispatched up to the prefetch value, and when the consumer
> > > closes, the remaining 900 will get dispatched again to another consumer.
> > >
> > > Hence dispatchCount total can increase past the enqueue count.
> > > The inflightCount is the sum of the current non committed prefetched
> > > messages for existing consumers.
> > >
> > > For more info on prefetch see:
> > > http://activemq.apache.org/what-is-the-prefetch-limit-for.html
> > >
> > >
> > > 2009/6/23 David Sitsky <sits@nuix.com>
> > >
> > > > 2009/6/19 Denis Bazhenov <bazhenov@farpost.com>:
> > > > > I'm interested in following topic. What does the InFlightCount mean
> > if
> > > > > JMX console for queue.
> > > > >
> > > > > It's seems like in flight count is difference between dequeue count
> > and
> > > > > dispatch count. But I have very strange situation.
> > > > >
> > > > > I have a queue which have following statistic:
> > > > >
> > > > > DequeueCount:  55189
> > > > > DispatchCount: 77525
> > > > > EnqueueCount:  55191
> > > > > InFlightCount: 22336
> > > > > QueueSize:     2
> > > > >
> > > > > How can I dispatch more messages than I enqueue? Can anyone explain
> > what
> > > > > does this numbers mean?
> > > >
> > > > Note that DequeueCount + InFlightCount == DispatchCount.
> > > >
> > > > From my understanding:
> > > >
> > > > EnqueueCount = Number of messages sent to a queue and committed.
> > > >
> > > > DequeueCount = Number of messages removed from a queue and committed.
> > > >
> > > > DispatchCount = Number of messages sent from this queue to consumers.
> > > > Includes messages which were not commit()ed, but rolledback.
> > > >
> > > > InFlightCount = Number of messages sent from this queue to consumers
> > > > that haven't been committed.
> > > >
> > > > Given you large difference in DispatchCount compared to DequeueCount,
> > > > perhaps a lot of your consumers are failing when they receive a
> > > > message, and don't call commit().
> > > >
> > > > --
> > > > Cheers,
> > > > David
> > > >
> > > > Nuix Pty Ltd
> > > > Suite 79, 89 Jones St, Ultimo NSW 2007, Australia    Ph: +61 2 9280
> > 0699
> > > > Web: http://www.nuix.com                            Fax: +61 2 9212
> > 6902
> > > >
> > >
> > >
> > >
> > --
> > Denis Bazhenov <bazhenov@farpost.com>
> > FarPost.
> >
> >
> 
> 
-- 
Denis Bazhenov <bazhenov@farpost.com>
FarPost.