2016-03-24 18:13:37 +00:00
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---
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layout: pattern
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title: Semaphore
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folder: semaphore
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permalink: /patterns/semaphore/
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2016-07-21 09:27:48 +03:00
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categories: Concurrency
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2016-03-24 18:13:37 +00:00
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tags:
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- Java
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2016-07-21 09:27:48 +03:00
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- Difficulty-Intermediate
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2016-03-24 18:13:37 +00:00
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---
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## Also known as
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Counting Semaphore
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## Intent
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Create a lock which mediates access to a pool of resources.
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Only a limited number of threads, specified at the creation
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of the semaphore, can access the resources at any given time.
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A semaphore which only allows one concurrent access to a resource
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is called a binary semaphore.
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## Applicability
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Use a Semaphore when
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* you have a pool of resources to allocate to different threads
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* concurrent access to a resource could lead to a race condition
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## Credits
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* [Semaphore(programming)] (http://en.wikipedia.org/wiki/Semaphore_(programming))
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* [Semaphores] (http://tutorials.jenkov.com/java-concurrency/semaphores.html)
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