Task (computing): Difference between revisions

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{{Use mdy dates|date=June 2015}}

[[File:Thread pool.svg|thumb|400px|A sample [[thread pool]] (green boxes) with [[task queue]]s of waiting '''tasks''' (blue) and completed '''tasks''' (yellow), in the sense of task as "unit of work".]]

In [[computers|computing]], a '''task''' is a unit of [[execution (computing)|execution]]. Inor somea [[operatingunit system]]s,of awork. taskThe term is synonymousambiguous; withmore aprecise alternative terms include ''[[process (computing)|process]]'', and in others with a ''[[thread (computing)|thread]]'' (for execution), or ''step'', ''[[request–response|request]]'', or ''query'' (for work). In the diagram at right, there are [[batchtask processingqueue|queues]] computerof systems,incoming awork taskto isdo aand unitoutgoing ofcompleted executionwork, withinand a [[jobthread (computing)|jobpool]].<ref>{{cite web|url=http://whatisof threads to perform this work.techtarget.com/definition/task|title=What isEither task?the -work Definitionunits fromthemselves or the threads that perform the WhatIs.com|work=WhatIs.com|accessdate=June 11can be referred to as "tasks", 2015}}</ref><ref>{{citeand web|url=http:these can be referred to respectively as requests/responses/www.liutilities.comthreads, incoming tasks/articlescompleted tasks/what-are-computer-processes/#.VXn8h0b7LDc|title=Whatthreads are(as computerillustrated), processes?|work=liutilities.com|accessdate=June 11,or 2015}}<requests/ref>responses/tasks.

==Terminology==

In the sense of "unit of execution", in some [[operating system]]s, a task is synonymous with a [[process (computing)|process]], and in others with a [[thread (computing)|thread]]. In non-interactive execution ([[batch processing]]), a task is a unit of execution within a [[job (computing)|job]],<ref>{{cite web|url=http://whatis.techtarget.com/definition/task|title=What is task? - Definition from WhatIs.com|work=WhatIs.com|accessdate=June 11, 2015}}</ref><ref>{{cite web|url=http://www.liutilities.com/articles/what-are-computer-processes/#.VXn8h0b7LDc|title=What are computer processes?|work=liutilities.com|accessdate=June 11, 2015}}</ref> with the task itself typically a process. The term "[[multitasking]]" primarily refers to the processing sense – multiple tasks ''executing'' at the same time – but has nuances of the work sense of multiple tasks being ''performed'' at the same time.

In the sense of "unit of work", in a job (meaning "one-off piece of work") a task can correspond to a single step (the step itself, not the execution thereof), while in [[batch processing]] individual tasks can correspond to a single step of processing a single item in a batch, or to a single step of processing all items in the batch. In online systems, tasks most commonly correspond to a single ''request'' (in [[request–response]] architectures) or a ''query'' (in [[information retrieval]]), either a single stage of handling, or the whole system-wide handling.

==History==