scheduleready

Scheduleready is a state used in computer scheduling to describe a task, process, or job that has satisfied all conditions required to begin execution and is eligible to be selected by the scheduler. In many systems, scheduleready corresponds to the contents of a ready queue, where all runnable tasks reside until the processor is assigned to one of them.

To reach scheduleready, tasks must have had dependencies resolved, necessary resources allocated and available, and any pending input data or I/O operations completed or arranged. In a multitasking operating system, the scheduler may include prerequisites such as priority, aging, CPU affinity, and preemption policies. A task marked scheduleready is typically not blocked by I/O waits, locks, or other blocking conditions; however, it may still be preempted by a higher-priority task or by a time slice expiration.

Usage of the concept helps separate tasks that are truly able to run from those that are waiting on external events. Scheduling decisions are then made among the pool of scheduleready tasks, with algorithms that may prioritize fairness, throughput, latency, or energy efficiency. In batch and distributed schedulers, scheduleready can indicate a job is ready to start on a compute resource.

Relation to other states: It is related to, but distinct from, the blocked or waiting state, where a task cannot proceed until some condition occurs. The term may appear in design documents or specific implementations of kernels or schedulers and is often implied by terms like runnable or ready.