Shortest job next

Shortest job next, also called shortest job first or shortest process next, is a scheduling policy an operating system uses to decide which waiting task runs first. It always chooses the waiting process with the smallest execution time. The policy is valued for its simplicity and because it minimizes the average time each process waits until it completes. Its drawbacks are that long processes can starve if short ones keep arriving, which highest response ratio next addresses with a technique called aging, and that the total execution time of a job must be known before it runs, so estimates such as a weighted average of previous execution times are used in practice. It is a non-preemptive algorithm, and shortest remaining time is its preemptive variant. A related modification, weighted shortest job first, is used in agile development to weight jobs by their cost of delay.