Project how a queue backlog grows or drains given arrival and processing rates.
A backlog only clears when processing exceeds arrivals, and the drain rate is the difference rather than the processing rate itself. A queue running at 95 per cent capacity takes twenty times longer to recover than one at 50 per cent. Recovery time after an incident depends entirely on spare capacity, which is why headroom sizing is a reliability decision.
Queue Backlog
Drain time = backlog ÷ (processing rate − arrival rate)
Drain time = backlog ÷ (processing rate − arrival rate) A backlog only clears when processing exceeds arrivals, and the drain rate is the difference rather than the processing rate itself. A queue running at 95 per cent capacity takes twenty times longer to recover than one at 50 per cent.
Recovery time after an incident depends entirely on spare capacity, which is why headroom sizing is a reliability decision.
This calculator takes 4 inputs: Current backlog, Messages arriving per second, Messages processed per second, Projection window. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.