Job control (computing): Difference between revisions

Revision as of 18:50, 9 May 2012

Revision as of 16:06, 22 August 2012

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{{Details|Job control (Unix)|Unix-specific job control}}

{{unreferenced|date=November 2008}}

'''Job control''' in [[computing]] refers to the control of multiple tasks or [[Job (software)|Job]]s on a computer system, ensuring that they each have access to adequate resources to perform correctly, that competition for limited resources does not cause a [[deadlock]] where two or more jobs are unable to complete, resolving such situations where they do occur, and terminating jobs that, for any reason, are not performing as expected.

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Job control has developed from the early days of computers where human [[Computer operator|operators]] were responsible for setting up, monitoring and controlling every job, to modern [[operating system]]s which take on the bulk of the work of job control.

Even with a highly sophisticated scheduling system, some human intervention is desirable. Modern systems permit their users to stop and resume jobs, to execute them in the foreground (with the ability to interact with the user) or in the background. See for instance [[Job control (Unix)|Unix-like systems follow this pattern]].

==History==

It became obvious to the early computer developers that their fast machines spent most of the time idle because the single program they were executing had to wait while a slow [[peripheral]] device completed an essential operation such as reading or writing data. [[Data buffer|Buffering]] only provided a partial solution; eventually an output buffer would occupy all available memory or an input buffer would be emptied by the program, and the system would be forced to wait for a relatively slow device to complete an operation.