[rabbitmq-discuss] what's the meaning of deliver and get ?

[Simon MacMullen]

On 31/01/13 07:08, andy lin wrote:
> <http://rabbitmq.1065348.n5.nabble.com/file/n24797/2.jpg>
>   In the picture , I find there are two value in the column of deliver/get,so
> I doubt that why it has two values and what  the meaning of them ,also you

For the record, your picture was very small and I couldn't read the 
text. But I know what that screen is supposed to look like.

However, to add to what people have already said:

* "deliver" refers to messages delivered as a result of basic.consume. * 
"get" refers to messages that arrived in response to basic.get.
* "deliver / get" is the sum of both.
* "ack" just shows the ack rate, if messages are delivered with autoack 
then this rate can be lower or zero.

However, the thing that everyone else missed :-) is that under 
"deliver/get" there is the text "(of which redelivered)". That's what 
the second figure in the cell is - it's showing the number of messages 
sent via deliver / get which have the redelivered flag set.

Messages with "redelivered" set may have already been delivered to a 
consumer once. Messages will be redelivered if the consumer dies or 
invokes basic.recover before acknowledging them, or if the consumer 
rejects / nacks them. (Or after HA failover, but I doubt that is what is 
happening.)

High rates of redelivery usually indicate unhealthy consumers - you 
should definitely investigate why so many messages are being redelivered!

> can see that the rate of deliver is 626 but the ack  is only 1.4/s
> so Could you tell me the reason and the difference between deliver and get?
>
> <http://rabbitmq.1065348.n5.nabble.com/file/n24797/11.jpg>
>
> In the picture ,there is only one value and the rate of deliver equals the
> ack.why?

Nothing is being redelivered in that case. If no messages are being 
redelivered the management web UI just hides everything to do with 
redelivery.

Cheers, Simon

-- 
Simon MacMullen
RabbitMQ, VMware