Editing Watchdog timer (section)

==Applications==

[[File:NASA Mars Rover.jpg|thumb|Watchdog timers are essential in remote, automated systems such as this [[Mars Exploration Rover]]]]

Watchdog timers are commonly found in [[embedded system]]s and other computer-controlled equipment where humans cannot easily access the equipment or would be unable to react to faults in a timely manner. In such systems, the computer cannot depend on a human to invoke a reboot if it [[hang (computing)|hangs]]; it must be self-reliant. For example, remote embedded systems such as [[space probe]]s are not physically accessible to human operators; these could become permanently disabled if they were unable to autonomously recover from faults. In [[robot]]s and other automated machines, a fault in the control computer could cause equipment damage or injuries before a human could react, even if the computer is easily accessed. A watchdog timer is usually employed in cases like these.

Watchdog timers are also used to monitor and limit software execution time on a normally functioning computer. For example, a watchdog timer may be used when running untrusted code in a [[sandbox (computer security)|sandbox]], to limit the CPU time available to the code and thus prevent some types of [[denial-of-service attack]]s.<ref name="grenade"/> In [[real-time operating system]]s, a watchdog timer may be used to monitor a time-critical task to ensure it completes within its maximum allotted time and, if it fails to do so, to terminate the task and report the failure.