> If the queue is not empty, it means that whatever job is consuming from the queue is not keeping up with messages coming into it. You could conceivably have

> If the queue is not empty, it means that whatever job is consuming from the queue is not keeping up with messages coming into it. You could conceivably have a non-zero queue size that asymptotically reaches some stable size over time. In such a case you are keeping up with messages but with some approximately static amount of added latency. I don’t think I’ve seen this happen in practice but I think some systems can be engineered to be approximately stable (grows and shrinks but within predictable bounds)