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From: Kevin Burton <burton@spinn3r.com>
Date: Fri, 24 Apr 2015 14:43:14 -0700
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Subject: =?UTF-8?Q?Re=3A_I_can_finally_somewhat_duplicate_the_bad_bug_I?=
	=?UTF-8?Q?=E2=80=99m_seeing_with_ActiveMQ_not_dispatching_messages=2E?=
To: users@activemq.apache.org
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On Fri, Apr 24, 2015 at 2:27 PM, Tim Bain <tbain@alumni.duke.edu> wrote:

> If every message has at least one consumer for which the consumer's
> selector matches the message, you'll eventually process every message.
>

That=E2=80=99s what I thought too,  but that doesn=E2=80=99t work.


> Consumers that have no messages matching their selector in the cursor wil=
l
> be delayed until the messages in front of their next one get consumed, bu=
t
> they'll do it eventually; I don't think you'd have a complete failure to
> process messages as Kevin described.  (Or maybe I'm reading the wrong thi=
ng
> into Kevin's description.  Kevin, can you confirm that you're getting NO
> messages to ANY consumer on your queue?)
>
>
Every message should be consumed.

I have basically for selectors:

artemis_priority > 4
artemis_priority =3D 4
artemis_priority < 4
artemis_priority is null

The last one was a fall through to consume messages once we first added the
artemis_priority header.

(artemis is the name of our internal codebase)

conceptually, I thought this might be an issue, which is why I designed the
selectors so that I don=E2=80=99t have to pre-read much.

I also confirm that once I remove the selector, I immediately start
receiving messages that should match the above priorities.

And if I change maxPageSize, it DOES work now =E2=80=A6 so eureka.  That=E2=
=80=99s a big
step.

Kevin, your screenshots didn't come through in my email client (Gmail) nor
> on the Nabble page; can you resend so we can see what you're seeing in JM=
X?
>

http://imgur.com/a/2myja


>
> Also, given the way cursors work, implementing priority using selectors i=
s
> never going to work.  At best you'll only be able to prioritize among the
> first N messages in the store at any point in time (with N =3D the number=
 of
> messages that will fit into the cursor), which will eventually result in
> you having only N lowest-priority messages so you'll process the
> low-priority messages while your high-priority consumers sit unable to
> reach the high-priority messages deeper in the store.  If you want to use
> selectors to implement priority, you're going to have to implement the
> enhancements to cursors that Jon and I were talking about on Wednesday.
>

URL to this?  Is this because with maxPageSize I=E2=80=99m getting partial =
priority?

If I=E2=80=99m already an in-memory store, is there any problem just settin=
g
maxPageSize to a HUGE number?

Kevin

--=20

Founder/CEO Spinn3r.com
Location: *San Francisco, CA*
blog: http://burtonator.wordpress.com
=E2=80=A6 or check out my Google+ profile
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