An apportioned queue data structure allows a server to specify allocation of resources to return requests according to a prescribed usage request. The data structure comprises an input queue comprising of a set of subqueues (also known as windows). Windows contain requests that will be processed over a fixed window of time. Received items are removed from the input queue and packed into the subqueues according to the service level agreement. These windows (and the elements present within) are then processed in the order of the windows queue (and the order in the window) are arranged. The time for each task is not known until after the request is processed and may be estimated. In a steady state of high load, a queue is created that returns requests tending toward requested percentages of the service level agreement.