Semaphore Constructor (Int32, Int32)


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Initializes a new instance of the Semaphore class, specifying the initial number of entries and the maximum number of concurrent entries.

Namespace:   System.Threading
Assembly:  System (in System.dll)

new : 
        initialCount:int *
        maximumCount:int -> Semaphore


Type: System.Int32

The initial number of requests for the semaphore that can be granted concurrently.

Type: System.Int32

The maximum number of requests for the semaphore that can be granted concurrently.

Exception Condition

initialCount is greater than maximumCount.


maximumCount is less than 1.


initialCount is less than 0.

This constructor initializes an unnamed semaphore. All threads that use an instance of such a semaphore must have references to the instance.

If initialCount is less than maximumCount, the effect is the same as if the current thread had called WaitOne (maximumCount minus initialCount) times. If you do not want to reserve any entries for the thread that creates the semaphore, use the same number for maximumCount and initialCount.

The following 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.

No code example is currently available or this language may not be supported.

Universal Windows Platform
Available since 8
.NET Framework
Available since 2.0
Portable Class Library
Supported in: portable .NET platforms
Windows Phone Silverlight
Available since 8.0
Windows Phone
Available since 8.1
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