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{{Short description|Techniques used by computers to manage components with limited availability}}
In [[computer programming]], '''resource management''' refers to techniques for managing [[System resource|resources]] (components with limited availability).
[[Computer program]]s may manage their own resources{{which|date=November 2016}} by using features exposed by [[programming language]]s ({{harvtxt|Elder|Jackson|Liblit|2008}} is a survey article contrasting different approaches), or may elect to manage them by a host – an [[operating system]] or [[virtual machine]] – or another program.
Host-based management is known as ''resource tracking,'' and consists of cleaning up resource leaks: terminating access to resources that have been acquired but not released after use. This is known as ''reclaiming'' resources, and is analogous to [[Garbage collection (computer science)|garbage collection]] for memory. On many systems, the operating system reclaims resources after the process makes the [[exit (system call)|exit]] [[system call]].
==Controlling access==
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{{main|resource contention}}
In computer science, [https://www.techtarget.com/whatis/definition/resource-contention resource contention] refers to a conflict that arises when multiple entities attempt to access a shared resource, like random access memory, disk storage, cache memory, internal buses, or external network devices.
==Memory management==
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==Basic techniques==
The basic approach to resource management is to acquire a resource, do something with it, then release it, yielding code of the form (illustrated with opening a file in [[Python (programming language)|Python]]):
<syntaxhighlight lang="python">
f = open(filename)
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</syntaxhighlight>
The above techniques – unwind protection (<code>finally</code>) and some form of encapsulation – are the most common approach to resource management, found in various forms in [[C Sharp (programming language)|C#]], [[Common Lisp]], [[Java (programming language)|Java]], [[Python (programming language)|Python]], [[Ruby (programming language)|Ruby]], [[Scheme (programming language)|Scheme]], and [[Smalltalk]],{{sfn|Beck|1997|pp=37–39}} among others; they date to the late 1970s in the [[NIL (programming language)|NIL]] dialect of Lisp; see {{section link|Exception handling|History}}. There are many variations in the implementation, and there are also significantly different [[#Approaches|approaches]].
== Approaches ==
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</syntaxhighlight>
In [[.NET Framework|.NET]], convention is to only have direct user of resources be responsible: "You should implement IDisposable only if your type uses unmanaged resources directly."<ref name="idisposable">{{cite web |url=https://msdn.microsoft.com/en-us/library/system.idisposable(v=vs.110).aspx |title=IDisposable Interface |accessdate=2016-04-03}}</ref>
In case of a more complicated [[object graph]], such as multiple objects sharing a resource, or cycles between objects that hold resources, proper resource management can be quite complicated, and exactly the same issues arise as in object finalization (via destructors or finalizers); for example, the [[lapsed listener problem]] can occur and cause resource leaks if using the
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| isbn = 978-0134769042
}}
* {{cite
|url = http://research.cs.wisc.edu/techreports/2008/TR1647.pdf
|first1 = Matt |last1 = Elder
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* [http://c2.com/cgi/wiki?DeterministicResourceManagement Deterministic Resource Management], ''[[WikiWikiWeb]]''
[[Category:Articles with example Python (programming language) code]]
[[Category:Programming constructs]]
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