php rabbitmq Per-Message TTL Issue

Question

I'm using different "Per Message TTL" in RabbitMQ queue, and I expect that messages with different TTL should be processed by consumer in due time.

To provide this behaviour, I use RabbitMQ queue with huge "x-message-ttl", I add messages to this queue with own value of "Per Message TTL"(see code below). For example add to queue messages with TTL 30, 20 and 10 seconds.

The problem in behaviour, how RabbitMQ process the messages with different "Per MessageTTL" in queue, the messages with largest TTL stop the messages with less TTL. So consumer process all mesages together, when largest TTL expire.

Publish message code:

$channel = new AMQPChannel($this->connection);    
$exchange = new AMQPExchange($channel);
$exchange->setName($exchangeName);
$exchange->setType(AMQP_EX_TYPE_DIRECT);        
$ttl = $ttl*1000;    
$params = array('expiration'=>$ttl);    
$message = $exchange->publish($msg, $this->queueNotDelayedName, null, $params);

theMayer theMayer · Accepted Answer · 2014-02-05T12:33:07

I'm going to be up-front that I don't fully understand your question, because the wording is confusing to me.

Are you referring to this (from the documentation)?

When setting per-message TTL however, expired messages can queue up behind non-expired ones until the latter are consumed or expired. Hence resources used by such expired messages will not be freed, and they will be counted in queue statistics (e.g. the number of messages in the queue).

I have not had issues using the per-message TTL feature. The messages expire before they get to the consumer. What the documentation says is that they are not expired in random order out of the queue, but that they are only expired when the message is to be "read" from the queue. Is this the cause of your issue?

php rabbitmq Per-Message TTL Issue

3 Answers