[rabbitmq-discuss] BUG: Failing nodes with HA-queue stops message flow

Mon Oct 1 13:59:23 BST 2012

Simon,

On 01/10/12 13:48, Simon Lundström wrote:
> It's when/after ram01 restarts that the consumer disappears from
> "Consumers" in the queue and message passing stops.

Are you handling the consumer cancellation notification? From 
http://www.rabbitmq.com/ha.html
<quote>
Clients that were consuming from the mirrored-queue [and were connected 
to a node other than the one that died] will receive a notification that 
their subscription to the mirrored-queue has been abruptly cancelled. At 
this point they should re-consume from the queue, which will pick up the 
new master.
</quote>

> Admittedly I'm new to AMQP and RabbitMQ, but I don't get why the
> consumer which is connected to disk01 would start failing when ram01 is
> being restarted.

The docs explain that:
<quote>
The reason for sending this notification is that informing clients of 
the loss of the master is essential: otherwise the client may continue 
to issue acknowledgements for messages they were sent by the old, failed 
master [these acks will be discarded], and not expect that they might be 
about to see the same messages again, this time sent by the new master.
</quote>

Regards,

Matthias.