SemaphoreFullException Class

[ This article is for Windows Phone 8 developers. If you’re developing for Windows 10, see the latest documentation. ]

The exception that is thrown when the Semaphore..::.Release method is called on a semaphore whose count is already at the maximum.

Inheritance Hierarchy


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


Public Class SemaphoreFullException _
    Inherits SystemException
public class SemaphoreFullException : SystemException

The SemaphoreFullException type exposes the following members.


Name Description
SemaphoreFullException()()() Initializes a new instance of the SemaphoreFullException class with default values.
SemaphoreFullException(String) Initializes a new instance of the SemaphoreFullException class with a specified error message.
SemaphoreFullException(String, Exception) Initializes a new instance of the SemaphoreFullException class with a specified error message and a reference to the inner exception that is the cause of this exception.



Name Description
Data Gets a collection of key/value pairs that provide additional user-defined information about the exception. (Inherited from Exception.)
HelpLink Gets or sets a link to the help file associated with this exception. (Inherited from Exception.)
HResult Gets or sets HRESULT, a coded numerical value that is assigned to a specific exception. (Inherited from Exception.)
InnerException Gets the Exception instance that caused the current exception. (Inherited from Exception.)
Message Gets a message that describes the current exception. (Inherited from Exception.)
Source Gets or sets the name of the application or the object that causes the error. (Inherited from Exception.)
StackTrace Gets a string representation of the frames on the call stack at the time the current exception was thrown. (Inherited from Exception.)



Name Description
Equals(Object) Determines whether the specified Object is equal to the current Object. (Inherited from Object.)
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.)
GetBaseException When overridden in a derived class, returns the Exception that is the root cause of one or more subsequent exceptions. (Inherited from Exception.)
GetHashCode Serves as a hash function for a particular type. (Inherited from Object.)
GetType Gets the runtime type of the current instance. (Inherited from Exception.)
MemberwiseClone Creates a shallow copy of the current Object. (Inherited from Object.)
ToString Creates and returns a string representation of the current exception. (Inherited from Exception.)



The count on a semaphore is decremented each time a thread enters the semaphore, and incremented when a thread releases the semaphore. When the count is zero, subsequent requests block until other threads release the semaphore. When all threads have released the semaphore, the count is at the maximum value specified when the semaphore was created. If a programming error causes a thread to call the Semaphore..::.Release method at this point, a SemaphoreFullException is thrown.


The Semaphore class does not enforce thread identity on calls to the WaitHandle..::.WaitOne and Semaphore..::.Release methods. It is not necessary for the same thread that called WaitOne to call Release.

SemaphoreFullException does not necessarily indicate a problem with the code where the exception occurred. Consider the following scenario: Thread A and thread B enter a semaphore that has a maximum count of two. A programming error in thread B causes it to call Release twice, so that the count on the semaphore is full. As a result, when thread A eventually calls Release, a SemaphoreFullException is thrown.

For a list of initial property values for an instance of the SemaphoreFullException class, see the SemaphoreFullException()()() constructor.


The following code example shows how a programming error in one thread can lead to a SemaphoreFullException in another thread: Two threads enter a semaphore. The second thread releases the semaphore twice, while the first thread is still executing its task. When the first thread finishes and releases the semaphore, the semaphore count is already full and an exception is thrown.

Version Information

Windows Phone OS

Supported in: 8.1, 8.0

Thread Safety

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

See Also


System.Threading Namespace