[rabbitmq-discuss] parallel consuming from one queue
Jan.Andersson at UNIBET.com
Fri Mar 25 08:10:45 GMT 2011
On 03/24/2011 05:50 PM, Emile Joubert wrote:
> Hi Jan,
> On 24/03/11 16:38, Jan Andersson wrote:
>> we are trying to setup something that we hoped would be pretty straight
>> forward but can't seem to get it to work.
>> We want to consume messages from a persistent queue and use ack:s.
>> However all of our attempts end in us consuming one message off the
>> queue and then no one else (thread or process) can consume messages off
>> the queue until that message has been ack:ed.
>> This is in Java, we set up one channel per thread like this:
>> channel = connection.createChannel();
>> channel.exchangeDeclare(configuration.getExchangeName(), "topic", true);
>> channel.queueDeclare(queueName, true); // durable queue
>> channel.queueBind(queueName, configuration.getExchangeName(),
>> consumer = new QueueingConsumer(channel);
>> channel.basicConsume(queueName, false, consumer);
>> The ack is done like this:
>> channel.basicAck(delivery.getEnvelope().getDeliveryTag(), false);
>> Might be hard to answer this but if anyone could point us in the right
>> direction that would be great!
> You should set QoS on each channel. The first QueueingConsumer has
> taken all the messages - that's why no other consumers can retrieve
> messages. Setting QoS will prevent the broker from delivering more
> than the set number of messages without acknowledgement and allow
> other consumers to retrieve some messages.
after setting the QoS like "channel.basicQos(1);" we can pickup messages
However, every message gets the deliveryTag set to 1. So when we ack the
2nd, 3rd... message we get the error:
channel error; reason:
unknown delivery tag 1,class-id=60,method-id=80),null,""}
Are we consuming the messages in the wrong way somehow?
(QueueingConsumer.Delivery delivery = consumer.nextDelivery();)
thanks for your quick reply,
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