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Semaphore

semaphore

/patterns/semaphore/

Concurrency

Java	Difficulty-Intermediate

Also known as

Counting Semaphore

Intent

Create a lock which mediates access to a pool of resources. Only a limited number of threads, specified at the creation of the semaphore, can access the resources at any given time. A semaphore which only allows one concurrent access to a resource is called a binary semaphore.

Applicability

Use a Semaphore when

you have a pool of resources to allocate to different threads
concurrent access to a resource could lead to a race condition

Credits

[Semaphore(programming)] (http://en.wikipedia.org/wiki/Semaphore_(programming))
[Semaphores] (http://tutorials.jenkov.com/java-concurrency/semaphores.html)