SemaphoreSlim Class
[ This article is for Windows Phone 8 developers. If you’re developing for Windows 10, see the latest documentation. ]
A lightweight alternative to Semaphore that limits the number of threads that can access a resource or pool of resources concurrently.
Inheritance Hierarchy
System..::.Object
System.Threading..::.SemaphoreSlim
Namespace: System.Threading
Assembly: mscorlib (in mscorlib.dll)
Syntax
Public Class SemaphoreSlim _
Implements IDisposable
public class SemaphoreSlim : IDisposable
The SemaphoreSlim type exposes the following members.
Constructors
| Name | Description | |
|---|---|---|
.gif "Public method") |
SemaphoreSlim(Int32) | Initializes a new instance of the SemaphoreSlim class, specifying the initial number of requests that can be granted concurrently. |
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SemaphoreSlim(Int32, Int32) | Initializes a new instance of the SemaphoreSlim class, specifying the initial and maximum number of requests that can be granted concurrently. |
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Properties
| Name | Description | |
|---|---|---|
.gif "Public property") |
AvailableWaitHandle | Returns a WaitHandle that can be used to wait on the semaphore. |
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CurrentCount | Gets the number of threads that will be allowed to enter the SemaphoreSlim. |
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Methods
| Name | Description | |
|---|---|---|
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Dispose()()() | Releases all resources used by the current instance of the SemaphoreSlim class. |
.gif "Protected method") |
Dispose(Boolean) | Releases the unmanaged resources used by the ManualResetEventSlim, and optionally releases the managed resources. |
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Equals(Object) | Determines whether the specified Object is equal to the current Object. (Inherited from Object.) |
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Finalize | Allows an object to try to free resources and perform other cleanup operations before the Object is reclaimed by garbage collection. (Inherited from Object.) |
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GetHashCode | Serves as a hash function for a particular type. (Inherited from Object.) |
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GetType | Gets the Type of the current instance. (Inherited from Object.) |
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MemberwiseClone | Creates a shallow copy of the current Object. (Inherited from Object.) |
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Release()()() | Exits the SemaphoreSlim once. |
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Release(Int32) | Exits the SemaphoreSlim a specified number of times. |
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ToString | Returns a string that represents the current object. (Inherited from Object.) |
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Wait()()() | Blocks the current thread until it can enter the SemaphoreSlim. |
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Wait(CancellationToken) | Blocks the current thread until it can enter the SemaphoreSlim, while observing a CancellationToken. |
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Wait(Int32) | Blocks the current thread until it can enter the SemaphoreSlim, using a 32-bit signed integer that specifies the timeout. |
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Wait(TimeSpan) | Blocks the current thread until it can enter the SemaphoreSlim, using a TimeSpan to specify the timeout. |
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Wait(Int32, CancellationToken) | Blocks the current thread until it can enter the SemaphoreSlim, using a 32-bit signed integer that specifies the timeout, while observing a CancellationToken. |
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Wait(TimeSpan, CancellationToken) | Blocks the current thread until it can enter the SemaphoreSlim, using a TimeSpan that specifies the timeout, while observing a CancellationToken. |
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WaitAsync()()() | Asynchronously waits to enter the SemaphoreSlim. |
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WaitAsync(CancellationToken) | Asynchronously waits to enter the SemaphoreSlim, while observing a CancellationToken. |
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WaitAsync(Int32) | Asynchronously waits to enter the SemaphoreSlim, using a 32-bit signed integer to measure the time interval. |
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WaitAsync(TimeSpan) | Asynchronously waits to enter the SemaphoreSlim, using a TimeSpan to measure the time interval. |
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WaitAsync(Int32, CancellationToken) | Asynchronously waits to enter the SemaphoreSlim, using a 32-bit signed integer to measure the time interval, while observing a CancellationToken. |
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WaitAsync(TimeSpan, CancellationToken) | Asynchronously waits to enter the SemaphoreSlim, using a TimeSpan to measure the time interval, while observing a CancellationToken. |
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Remarks
The SemaphoreSlim provides a lightweight semaphore class that doesn't use Windows kernel semaphores.
Examples
The following example shows how to use a SemaphoreSlim:
Version Information
Windows Phone OS
Supported in: 8.1, 8.0
Thread Safety
All public and protected members of SemaphoreSlim are thread-safe and may be used concurrently from multiple threads, with the exception of Dispose, which must only be used when all other operations on the SemaphoreSlim have completed.