I'm trying to stay connected to multiple queues in RabbitMQ. Each time I pop a new message from one of these queue, I'd like to spawn an external process.
This process will take some time to process the message, and I don't want to start processing another message from that specific queue until the one I popped earlier is completed. If possible, I wouldn't want to keep a process/thread around just to wait on the external process to complete and ack the server. Ideally, I would like to ack in this external process, maybe passing some identifier so that it can connect to RabbitMQ and ack the message.
Is it possible to design this system with RabbitMQ? I'm using Python and Pika, if this is relevant to the answer.
Thanks!
RabbitMQ can do this.
You only want to read from the queue when you're ready - so spin up a thread that can spawn the external process and watch it, then fetch the next message from the queue when the process is done. You can then have mulitiple threads running in parallel to manage multiple queues.
I'm not sure what you want an ack for? Are you trying to stop RabbitMQ from adding new elements to that queue if it gets too full (because its elements are being processed too slowly/not at all)? There might be a way to do this when you add messages to the queues - before adding an item, check to make sure that the number of messages already in that queue is not "much greater than" the average across all queues?
RabbitMQ: Consuming only one message at a time from multiple queues