Task (computing): Difference between revisions

Revision as of 22:22, 24 November 2022

Latest revision as of 17:32, 17 March 2023

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===Examples===

In the [[Java (programming language)|Java]] programming language, these two concepts (unit of work and unit of execution) are conflated when working directly with threads, but clearly distinguished in the [https://docs.oracle.com/javase/tutorial/essential/concurrency/executors.html Executors] framework:

{{quote|When you work directly with threads, a <code>Thread</code> serves as both a unit of work and the mechanism for executing it. In the executor framework, the unit of work and the execution mechanism are separate. The key abstraction is the unit of work, which is called a ''task''.<ref>{{cite book |author-link = Joshua Bloch |first = Joshua |last = Bloch |title = Effective Java |edition = Third |page=[https://books.google.com/books?id=BIpDDwAAQBAJ&lpg=PT431&ots=LwbKdbR4_b&dq=%22the%20key%20abstraction%20is%20the%20unit%20of%20work+key+abstraction+is+the+unit+of+work%22&pg=PT431#v=onepage&q=%22the%20key%20abstraction%20is%20the%20unit%20of%20work%22&f=false p. 272], Item 68}}</ref>}}

===IBM terminology===

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==History==

The term ''task'' for a part of a job dates to [[multiprogramming]] in the early 1960s, as in this example from 1961:

{{quote |The serial model has the ability to process tasks of one job in an independent manner similar to the functioning of the [[IBM 709]].<ref>{{cite book |title=Simultaneous multiprogramming of electronic computers |year=1961 |author=James Larrimore McKenney |page=[https://books.google.com/books?id=ThYcAQAAMAAJ&dqq=%22tasks+of+one+job%22 154]}}</ref>}}

The term was popularized with the introduction of [[OS/360 and successors|OS/360]] (announced 1964), which featured [[OS/360 and successors#MFT|Multiprogramming with a Fixed number of Tasks]] (MFT) and [[OS/360 and successors#MVT|Multiprogramming with a Variable number of Tasks]] (MVT). In this case tasks were identified with light-weight processes, a job consisted of a number of tasks, and, later, tasks could have sub-tasks (in modern terminology, [[child process]]es).