[rabbitmq-discuss] Prefetch fields in management UI

Ben Hood 0x6e6562 at gmail.com
Wed Apr 23 13:55:49 BST 2014

On Wed, Apr 23, 2014 at 9:08 AM, Simon MacMullen <simon at rabbitmq.com> wrote:
> Note that the semantics of qos have changed in 3.3.0:
> http://www.rabbitmq.com/consumer-prefetch.html
> Per-consumer prefetch will be fixed at the moment the consumer is created.
> Per-channel prefetch can be changed after the fact, as before. But it was
> never a great idea to do that since if you set qos after consuming then the
> broker can deliver as many messages as it wants in between the two commands,
> which is unlikely to be what you want.

Yep, that all makes sense and the change in the scope of qos in 3.3 is
really good idea.

So the take home is that you could have an app with a bug in it
(issuing qos after the consume), then a pre-3.3 broker would mask this
issue for you. So app only then becomes really broken after upgrading
to 3.3.

But the fix is simple.



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