Time is a Resource, and Other Stories

Abstract

Computation, as expressed in modern programming languages, obscures many resource management problems. Memory is provided without bound by stacks and heaps. Power and energy consumption are not the concern of a programmer. Even when these resource management problems are important, there is no way to talk about them within the semantics of a programming language. Time, however, is not quite like these other resources. First, barring metaphysical discourse, it is genuinely unbounded. To say that "the available time per unit time is bounded" is tautological, yet this is effectively what people say when they manage it as a bounded resource. Second, time gets expended whether we use it or not. It cannot be conserved and saved for later. This is true up to a point with, say, battery power. Batteries leak, so their power cannot be indefinitely conserved, but designers rarely optimize a system to use as much battery power before it leaks away as they can. Yet that is what they do with time.