Thanks Gordon, and Sandy. With RabbitMQ if a message is silently dropped by the broker will a timeout still occur/exception be raised because no reply/ack was received?
With the QPID driver the automatic ack()'s Sandy mentioned don't occur? Will the sender eventually become aware that a message was lost? I'll take a timeout over a silent message drop any day. Thanks! -Aaron On Tue, Oct 14, 2014 at 1:33 PM, Gordon Sim <g...@redhat.com> wrote: > I agree that greater clarity on expectations around reliability are needed. > > The drivers all differ in this regard. > > As it stands today, the impl_rabbit driver only retries an RPC request if > an exception occurs while sending it. However messages are sent > unconfirmed[1]. This means a message can be lost before it gets enqueued by > the broker, without the sender of the message receiving any error or > notification of that fact. > > Even if the requests are durably stored and/or replicated in a clustered > RabbitMQ configuration, the reply queues are currently always auto-deleted > and are not durable regardless of configuration, so replies may be lost on > broker failure even if requests are not. > > So I believe that various failures may cause an RPC request to fail (i.e. > to timeout). It seems this is not universally expected however, so I am not > sure how many OpenStack services using oslo.messaging expect and handle > such failures. > > --Gordon > > [1] The impl_qpid driver by contrast sends messages synchronously - i.e. > blocking until confirmed, but on the receive side it does not use > acknowledgements so again message loss is possible. > > > _______________________________________________ > Mailing list: http://lists.openstack.org/cgi-bin/mailman/listinfo/ > openstack > Post to : openstack@lists.openstack.org > Unsubscribe : http://lists.openstack.org/cgi-bin/mailman/listinfo/ > openstack >
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