Rabbitmq : Prioritize consuming messages from multiple queues

Question

If I have two queues from which I want to consume messages, and I use a single SimpleMessageQueueListenerContainer for it, in which order would the listeners be invoked/messages consumed when both queues have messages?

I will try to be more specific of the problem I am working on:

I have a consumer application which needs to consume messages from 2 queues – say regular-jobs-queue and infrequent-jobs-queue. If there are any messages in ‘infrequent-jobs-queue’ I want to consume those before consuming messages from ‘regular-jobs-queue’. I might not be able to combine these and put all messages into a single rabbitmq level priority queue and assign higher priority to infrequent-job message because of some upcoming use-cases like purging regular-jobs without affecting infrequent-jobs and others.

I am aware that RabbitMQ has support for consumer priority but I am not very sure if it will be applicable here. I want all instances of my consumer application to first consume messages of infrequent-jobs-queue if any and not prioritize amongst these consumers.

Or should I like have 2 containers, with dedicated consumer thread(s) per queue and have an internal priority-queue data structure into which I can put messages as and when consumed from rabbitmq queue.

Any help would be really appreciated. Thanks.

~Rashida

Answer 1

You can't do what you want; messages will be delivered with equal priority.

Moving them to an internal in-memory queue will risk message loss.

You might want to consider using one of the RabbitTemplate.receive() or receiveAndConvert() methods instead of a message-driven container.

That way you have complete control.