Polling reliably at scale using DLQs

I would _not_ recommend using DLQs in ActiveMQ as a delivery delay mechanism. DLQs are meant to hold bad messages that can't be processed by your consumers. Conflating those with good messages most certainly sounds like a debugging nightmare. Imagine your database going down and thousands of messages heading to your DLQ... you'd want to replay those so you don't lose valuable data. Mixing that with stuff that needed to run into the future sounds like a true headache.

ActiveMQ is an amazing toolbox however. In fact, it contains the exact feature they want (and surprised they did not mention). Internally it is driven by a robust Quartz scheduler. You simple enable scheduling on your broker config (schedulerSupport="true") then all you would need to do is put a header on your messages AMQ_SCHEDULED_DELAY with the number of ms to delay.