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From Tim Bain <tb...@alumni.duke.edu>
Subject Re: Selective consuming of priority messages with message groups
Date Tue, 15 Dec 2015 13:58:19 GMT
You get all the things you described by continuing to use
policy.setPrioritizedMessages(true) and not having selectors on priority.
Normal-priority messages are still processed before low-priority messages
when both are waiting, and messages in a group are still processed one at a
time.  But you now have more consumers who can more quickly work on
normal-priority messages to get through them quickly, and more consumers
who can work on low-priority messages if you're lucky enough to get through
all the normal-priority ones, since all consumers are now allowed to
consume all messages.  Plus you no longer have the problem that made you
ask for help in the first place, which is the goal anyway.

What's the cost?  If there are no normal-priority messages in the queue (so
all consumers are consuming low-priority messages) when a normal-priority
message arrives, there is no longer a dedicated consumer sitting idle who
can start processing it immediately, and you have to wait for the consumer
for that message group to finish its current message before it picks up the
new message.  But that seems like a perfectly acceptable downside in light
of all the advantages, given that you haven't said that low-priority
messages take an unreasonable amount of time to process, especially since
your current implementation is broken anyway.

Tim
On Dec 14, 2015 11:34 AM, "artnaseef" <art@artnaseef.com> wrote:

> To acheive the split between "high priority" and "low priority" without
> starving the low-priority messages, I recommend:
>
> 1. use separate queues to split the priorities
> 2. either use dedicated consumers for the low priorities that do not take
> resources away from the higher priorities, or use some form of simple
> heuristic to choose when to process the same (e.g. after processing 10
> high-priority messages, process 1 low-priority message)
>
> The use of a heuristic will be important to allow the balance between
> starving low-priority messages and delaying high-priority ones.
>
> Messaging features, such as priority queueing, are limited and not likely
> to
> give you the desired results.
>
> BTW, I may have missed it - why use message groups?  Is messaging order
> important?
>
>
>
> --
> View this message in context:
> http://activemq.2283324.n4.nabble.com/Selective-consuming-of-priority-messages-with-message-groups-tp4704813p4704938.html
> Sent from the ActiveMQ - User mailing list archive at Nabble.com.
>

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