[rabbitmq-discuss] Sematics of ACK/REQUEUE/DISCARD on a message

[Andreas Jung]

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Matthias Radestock wrote:
> Matthew Sackman wrote:
>> On Wed, May 05, 2010 at 07:51:35PM +0200, Andreas Jung wrote:
>>> Two questions:
>>>
>>> - - assuming a consumer could process a message with success - what is
>>>   the difference in the message handling inside the queue between
>>>   acknowledging it or discarding it - it will be removed from the queue
>>>   in both cases?!
>> If you don't ack it, it will be retained by RabbitMQ and will be
>> redelivered to some other consumer eventually when your current
>> consumer cancels/dies.
> 
> Careful here - cancelling a consumer with basic.cancel does *not* cause 
> unack'ed messages to be requeued/redelivered. For that to happen the 
> channel needs to be closed (explicitly, or implicitly via a connection 
> closure or termination).

Fair enough. Using Python you would ensure that the related code is
properly enclosed within a context manager. For the case the consumer
dies for whatever reasons: the channel would be closed and the action
taken by the queue as you described it.

Andreas
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