View source for Timeout (computing)

{{Short description|Elapsed time before a specified event is to take place}}
{{No footnotes|date=January 2019}}

[[File:After earthquake INGV site down - 5 April 2009.jpg|thumb|Network timeout preventing a Web browser from loading a page]]

In [[telecommunication]]s and related engineering (including [[computer networking]] and [[Computer programming|programming]]), the term '''timeout''' or '''time-out''' has several meanings, including:

* A [[telecommunications network|network]] parameter related to an enforced [[Event-driven programming|event]] designed to occur at the conclusion of a predetermined elapsed [[time]].  
* A specified period of time that will be allowed to elapse in a [[system]] before a specified event is to take place, unless another specified event occurs first; in either case, the period is terminated when either event takes place.  Note:  A timeout condition can be canceled by the receipt of an appropriate time-out cancellation [[Signaling (telecommunications)|signal]]. 
* An event that occurs at the end of a predetermined period of time that began at the occurrence of another specified event. The timeout can be prevented by an appropriate signal.

Timeouts allow for more efficient usage of limited resources without requiring additional interaction from the agent interested in the goods that cause the consumption of these resources. The basic idea is that in situations where a system must wait for something to happen, rather than waiting indefinitely, the waiting will be aborted after the timeout period has elapsed. This is based on the assumption that further waiting is useless, and some other action is necessary.

==Challenges==
Balancing timeout values in distributed systems and microservices can be tricky: short timeout values can fail healthy requests prematurely, leading to complex workarounds, while long timeout values can result in slow error responses and poor user experiences. The [[circuit breaker design pattern]] can be a better alternative, as it can monitor service health, detect failures dynamically and faster, and improve the user experience.<ref>{{Cite book |last=Richards |first=Mark |title=Microservices AntiPatterns and Pitfalls |publisher=O'Reilly}}</ref>

==Examples==
{{Infobox software
| name                   = timeout
| logo                   = 
| screenshot             = Timeout Command - cmd.png
| screenshot size        = 
| caption                = The {{code|timeout}} command on [[Microsoft Windows]]
| developer              = [[Microsoft]], ReactOS Contributors
| released               = 
| latest release version = 
| latest release date    = 
| operating system       = [[Microsoft Windows|Windows]], [[ReactOS]]
| genre                  = [[Command (computing)|Command]]
| license                = Windows: [[Proprietary software|Proprietary]] [[commercial software]]<br />
ReactOS: [[GNU General Public License]]
| website                = {{URL|https://docs.microsoft.com/en-us/windows-server/administration/windows-commands/timeout_1}}
}}
Specific examples include:
* In the [[Microsoft Windows]] and [[ReactOS]]<ref>{{Cite web|url=https://github.com/reactos/reactos/blob/master/base/applications/cmdutils/timeout/timeout.c|title=timeout.c|date=July 13, 2019|via=GitHub}}</ref> [[command-line interface]]s, the <code>timeout</code> [[command (computing)|command]] pauses the command processor for the specified number of seconds.<ref>{{Cite web|url=https://docs.microsoft.com/en-us/windows-server/administration/windows-commands/timeout_1|title=timeout|website=docs.microsoft.com|date=3 February 2023 }}</ref><ref>{{Cite web|url=https://ss64.com/nt/timeout.html|title=TIMEOUT.exe (Windows 7/2008 or later)|website=ss64.com}}</ref>
* In [[Post Office Protocol|POP]] connections, the server will usually close a client connection after a certain period of inactivity (the timeout period).  This ensures that connections do not persist forever, if the client crashes or the network goes down.  Open connections consume resources, and may prevent other clients from accessing the same mailbox.
* In [[HTTP persistent connections]], the web server saves opened connections (which consume [[CPU time]] and [[computer memory|memory]]). The web client does not have to send an "end of requests series" signal.  Connections are closed (timed out) after five minutes of inactivity; this ensures that the connections do not persist indefinitely.
* In a timed light switch, both [[energy]] and lamp's [[life-span]] are saved. The user does not have to switch off manually.
* [[Tablet computer]]s and [[smartphone]]s commonly turn off their [[backlight]] after a certain time without user input.

==See also==
{{Wikibooks|Guide to Windows Commands}}
* [[Fibre Channel time out values]]
* [[Human-Machine Interaction]]
* [[Permanent signal]]

==References==
{{Reflist}}
{{refbegin}} 
*{{FS1037C MS188}}
{{refend}}

==Further reading==
*{{Cite book|author=John Paul Mueller|year=2007|title=Windows Administration at the Command Line for Windows Vista, Windows 2003, Windows XP, and Windows 2000|publisher=[[Wiley (publisher)|John Wiley & Sons]]|isbn=978-0470165799}}

{{Windows commands}}
{{Core Utilities commands}}

[[Category:Computer programming]]
[[Category:Telecommunications engineering]]
[[Category:Computer networking]]