[rabbitmq-discuss] Lack of Ack, Failure and Re-delivery

Bell, Paul M. pbell at syncsort.com
Sat Jan 21 22:18:58 GMT 2012

I apologize. I should have stated up front that the queues and messages are durable.

What happens in case 2, where the consumer bounces?

Thanks, Jason.


From: Jason J. W. Williams [jasonjwwilliams at gmail.com]
Sent: Saturday, January 21, 2012 5:05 PM
To: Bell, Paul M.
Cc: rabbitmq-discuss at lists.rabbitmq.com
Subject: Re: [rabbitmq-discuss] Lack of Ack, Failure and Re-delivery

Hi Paul,

If the messages were published with the durable flag and the queues are durable, the messages will survive the broker restart and be re-presented to consumers. If the messages or the queues were not durable they will disappear after restart.


Sent via iPhone

Is your email Premiere?

On Jan 21, 2012, at 14:57, "Bell, Paul M." <pbell at syncsort.com> wrote:

> Hi,
> Suppose I have a producer on NodeP, a broker on NodeB, and a consumer on NodeC. Suppose further that explicit acks are required (i.e., if I've understood the docs, that "noack" is not in effect) and that after consuming a message from the queue, NodeC.consumer dispatches some other work in order to process that message. IOW: NodeC.consumer doesn't respond immediately with an ack.
> So, from NodeB.broker's point of view, the message has been moved from the exchange to the queue, consumed, but not yet ack-ed.
> What will happen under these two scenarios:
> 1. NodeB.broker bounces - when broker restarts what will he do with un-acked messages that have been delivered to queue and haven't been ack-ed; e.g., will these be again delivered to the queue?
> 2. NodeC.consumer bounces - when consumer restarts is there any way he can again consume the un-acked message, and begin again the work that this message represents? (I suppose that NodeB.broker might be implicated here because it might detect the loss of connection to the NodeC.consumer....).
> When I say "bounces," I mean at a minimum that the application (broker, consumer) crashed and restarted. But I am also interested in the case where the node's OS is for whatever reason rebooted. Perhaps it looks no different.
> Thanks for your help.
> -Paul
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