| ←Older revision | Revision as of 05:33, 10 October 2023 | ||
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| - | Fighting problems with [[ImpossibleThreading|threading may seem impossible]], but there is an easy way avoid [[deadlock]]s. Just make sure | + | Fighting problems with [[ImpossibleThreading|threading may seem impossible]], but there is an easy way avoid [[deadlock]]s. Just make sure '''one''' (enough if only one) of following conditions isn't true. Then a [[deadlock]] cannot occur. |
== Mutual exclusion == | == Mutual exclusion == | ||
| ←Older revision | Revision as of 05:33, 10 October 2023 | ||
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| + | Fighting problems with [[ImpossibleThreading|threading may seem impossible]], but there is an easy way avoid [[deadlock]]s. Just make sure **one** (enough if only one) of following conditions isn't true. Then a [[deadlock]] cannot occur. | ||
| + | |||
== Mutual exclusion == | == Mutual exclusion == | ||
| ←Older revision | Revision as of 08:45, 1 August 2018 | ||
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| - | There must be a way to request another resource while already holding some. If a thread can only request resource(s) while holding none (or there is some order of resources and those can be requested only in such order), a deadlock cannot be created. | + | There must be a way to request another resource while already holding some. If a thread can only request resource(s) while holding none (or there is some order of resources and those can be requested only in such order), a [[deadlock]] cannot be created. |
Resource waiting or circular wait
| ←Older revision | Revision as of 07:52, 19 October 2014 | ||
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Nobody can take away a resource from a thread. If there was a supervisor, that could take the resource away, it could effectively solve all deadlocks by detecting them (which is easy) and then choosing a thread to loose its resource while letting others proceed. | Nobody can take away a resource from a thread. If there was a supervisor, that could take the resource away, it could effectively solve all deadlocks by detecting them (which is easy) and then choosing a thread to loose its resource while letting others proceed. | ||
| - | == | + | == Incremental Requests == |
| - | |||
| - | + | There must be a way to request another resource while already holding some. If a thread can only request resource(s) while holding none (or there is some order of resources and those can be requested only in such order), a deadlock cannot be created. | |
Hold and wait
| ←Older revision | Revision as of 07:51, 19 October 2014 | ||
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== Hold and wait == | == Hold and wait == | ||
| - | + | A thread can hold and wait indefinitely. If it could not, and for example would time out, the deadlock can be resolved by letting the timed out thread to give up and release all resources. | |
== Cannot Take Away a Resource == | == Cannot Take Away a Resource == | ||
No pre-emption
| ←Older revision | Revision as of 07:49, 19 October 2014 | ||
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There must be a way to request another resource while already holding some. If a thread can only request resource(s) while holding none, a deadlock cannot be created. | There must be a way to request another resource while already holding some. If a thread can only request resource(s) while holding none, a deadlock cannot be created. | ||
| - | == | + | == Cannot Take Away a Resource == |
| - | + | Nobody can take away a resource from a thread. If there was a supervisor, that could take the resource away, it could effectively solve all deadlocks by detecting them (which is easy) and then choosing a thread to loose its resource while letting others proceed. | |
== Resource waiting or circular wait == | == Resource waiting or circular wait == | ||
Hold and wait or partial allocation
| ←Older revision | Revision as of 07:47, 19 October 2014 | ||
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The resources involved must be exclusive. Once a thread gets on hold of a resource, nobody else can use it. Otherwise the concurrent threads would not be prevented from using the resource. | The resources involved must be exclusive. Once a thread gets on hold of a resource, nobody else can use it. Otherwise the concurrent threads would not be prevented from using the resource. | ||
| - | == Hold and wait | + | == Hold and wait == |
| - | + | There must be a way to request another resource while already holding some. If a thread can only request resource(s) while holding none, a deadlock cannot be created. | |
== No pre-emption == | == No pre-emption == | ||
Mutual exclusion
| ←Older revision | Revision as of 07:46, 19 October 2014 | ||
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== Mutual exclusion == | == Mutual exclusion == | ||
| - | The resources involved must be | + | The resources involved must be exclusive. Once a thread gets on hold of a resource, nobody else can use it. Otherwise the concurrent threads would not be prevented from using the resource. |
| - | + | ||
== Hold and wait or partial allocation == | == Hold and wait or partial allocation == | ||
New page: == Mutual exclusion == The resources involved must be unshareable; otherwise, the processes would not be prevented from using the resource when necessary. == Hold and wait or partial al...
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