[rabbitmq-discuss] BasicQoS usage: consuming 1 by 1 messages avoind unacking the whole queue

[Matthias Radestock]

Alfonso,

On 20/04/11 08:50, Alfonso Pantoja wrote:
> Regarding basic.qos...
>
> Having prefetchCount=1 what happens if 2 consumers consume from the
> same queue?

basic.qos is a channel setting, so the quota set that way is shared by 
all consumers on that channel.

> Consider this scenario:
>
> *3 messages on the queue Q1: M2, M1
> *2 consumers consuming from Q1: C1, C2
> *Consumers connected using basic.qos(prefetchSize=0, prefetchCount=1,
> global=false)
>
> 1. Is it possible to achieve this behavior? "C1 gets M1 and  C2 does
> not get message M2  until C1 acks or rejects M1" (some kind of
> blocking the queue until messages are acked or rejected)

That can only happen if C1 and C2 are on the same channel.

> setting QoS means that acks or rejects are mandatory?

Unless consuming in noack mode, generally consumers are expected to 
(eventually) ack or reject messages they have received.

Regards,

Matthias.