[rabbitmq-discuss] RECONDITION_FAILED - unknown delivery tag

Matthias Radestock matthias at rabbitmq.com
Mon May 6 10:09:08 BST 2013

On 05/05/13 23:48, macmillan.josh09 at gmail.com wrote:
> My Node.js worker crashes (RECONDITION_FAILED - unknown delivery tag) if
> the following 2 conditions are met:
> 1. I start it AFTER the queue have at least 2 messages.
> 2. The q.shift() is in an async code.
> http://pastebin.com/uMQJn0Fe

Looking at the amqp.js code, q.shift() acknowledges the last message 
that was received. So with your code...

>          q.subscribe({ack:true, prefetchCount: 0}, function (message,
>     headers, deliveryInfo) {
>            console.log(message);
>            setTimeout(function() { q.shift(); }, 100);
>     });
>     });

due to the delayed execution, when two messages arrive in quick 
succession then the first to arrive won't be acknowledged at all and the 
second will be acknowledged twice. Rabbit is complaining about the latter.

I've never used node-amqp, so I don't know what the correct approach is 
for accomplishing what you want to do. You may want to ask the node-amqp 


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