[rabbitmq-discuss] unacknowledged messages lost after broker kill, despite consumer txCommit and noAck

Thu Nov 4 14:02:23 GMT 2010

On Thu, Nov 4, 2010 at 13:58, Marek Majkowski <majek04 at gmail.com> wrote:
> On Fri, Oct 29, 2010 at 19:46, rjwirth <rwirth at demandware.com> wrote:
>>> If you really need messages to go safely to disk, then you should put
>>> the channel into transactional mode (tx.select), and issue a tx.commit
>>
>> What about unacknowledged messages?
>>
>> A Producer (rabbit 2.1.1 java client, not Spring Rabbit AMQP) commits some
>> persistent messages on a durable queue/exchange.
>>
>> The Consumer is neither ack'ing nor rejecting the message to leave it on the
>> queue (and let recovery retry it later), but I am committing periodically,
>> e.g.:
>>
>>  QueueingConsumer.Delivery delivery = consumer.nextDelivery();
>>  // neither channel.basicReject or Ack
>>  channel.txCommit();
>>
>> Per ctl:
>>
>>  $ rabbitmqctl list_queues name messages messages_unacknowledged
>> messages_ready
>>  Listing queues ...
>>  testQueue       5       5       0
>>
>> Using a soft "rabbitmqctl stop", a Broker restart will make the
>> unacknowledged messages ready again (as expected).
>>  testQueue       5       0       5
>>
>> With a Broker hardkill, the unack'd messages disappear even after I have
>> just committed the channel
>>  testQueue       0       0       0
>>
>> Is there anything to commit on the channel if the Broker didn't get an Ack?
>> Shouldn't the "lease" of the message be at least committed?
>
> Hi,
>
> Maybe I missed something, but I'm not able to reproduce your results.
> 1. I publish 5 persistent messages in a transaction (tx_select, tx_commit).
> 2. I receive all of them, with no_ack=False and not acknowledge manually.
> 3. Restart the server.
>
> For both, hard kill and `rabbitmqctl stop` I'm able to see the messages after
> rabbit is up again.
>
> Did I get everything right?

I see the same results when I do receive messages in a committed
transaction (still without acking).

Marek