Semaphore.Release Method
[ This article is for Windows Phone 8 developers. If you’re developing for Windows 10, see the latest documentation. ]
Exits the semaphore and returns the previous count.
Assembly: System (in System.dll)
| Exception | Condition |
|---|---|
| SemaphoreFullException | The semaphore count is already at the maximum value. |
| IOException | A Win32 error occurred with a named semaphore. |
| UnauthorizedAccessException | The current semaphore represents a named system semaphore, but the user does not have the necessary access control rights.. |
Threads typically use the WaitOne method to enter the semaphore, and they typically use this method overload to exit.
If a SemaphoreFullException is thrown by the Release method, it does not necessarily indicate a problem with the calling thread. A programming error in another thread might have caused that thread to exit the semaphore more times than it entered.
The following code example creates a semaphore with a maximum count of three and an initial count of zero. The example starts five threads, which block waiting for the semaphore. The main thread uses the Release(Int32) method overload to increase the semaphore count to its maximum, allowing three threads to enter the semaphore. Each thread uses the Thread.Sleep method to wait for one second, to simulate work, and then calls the Release method overload to release the semaphore.
Each time the semaphore is released, the previous semaphore count is displayed. Console messages track semaphore use. The simulated work interval is increased slightly for each thread, to make the output easier to read.