[rabbitmq-discuss] Problem with publish confirms

Simon MacMullen simon at rabbitmq.com
Mon Apr 7 18:25:03 BST 2014

On 07/04/2014 18:07, Ryan Brown wrote:
> However, that said, I am curious about the option of just using
> amqp_channel:wait_for___confirms/1. I did not use this option for a
> couple of reasons.
> First was the fact that using the registered handler is mentioned quite
> often as the preferred option. My understanding was that using the
> amqp_channel:wait_for___confirms would cause the channel to wait for a
> response before another message could be published on that channel. If
> this is true, it seems like it could slow-down publishing more than
> registering a handler and letting publishing continue. Is this correct?
> Or am I misunderstanding the whole workflow?

It's possible I misunderstood you. I thought you were waiting for the 
confirm - i.e. you were effectively reimplementing wait_for_confirms() 
anyway. Yes, it is slower to call wait_for_confirms() (especially if you 
call it frequently) as you will stop publishing.

> Speaking of misunderstandings; the second reason I did not use
> wait_for_confirms was that I didn't completely understand the definition:
> "Wait until all messages published since the last call have been either
> ack'd or nack'd by the broker; or until timeout elapses."
> What exactly does it mean by the "last call"?

The last call to wait_for_confirms().

> This sounded to me as if
> it may get in a situation that if calls are coming-in rapidly enough
> that they are publishing new messages prior to the previous message
> getting ack'd, it would not respond until all such queued messages were
> ack'd/nack'd.

Yes, that's correct.

Cheers, Simon

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