Do I need to Dispose a SemaphoreSlim?

by

If you access the AvailableWaitHandle property, then Yes, you must call Dispose() to cleanup unmanaged resources.

If you do not access AvailableWaitHandle, then No, calling Dispose() won’t do anything important.

SemaphoreSlim will create a ManualResetEvent on demand if you access the AvailableWaitHandle. This may be useful, for example if you need to wait on multiple handles. If you do access the AvailableWaitHandle property, and then fail to call Dispose() you will have a leaked ManualResetEvent, which presumably wraps a handle to an unmanaged CreateEvent resource that needs a corresponding call to CloseHandle to clean up.

As other posters have pointed out, you should call Dispose() when you are done with any object that implements IDisposable. In this case, there are several risks to ignoring that practice, even though it may technically be safe to do so:

  1. My statements are based the reference source code to .NET 4.6.1. There is always the slim (pun intended) possibility that some future version of the framework will change SemaphoreSlim to where Dispose() is required.
  2. If your SemaphoreSlim is exposed outside of your class, calling code might reference the AvailableWaitHandle property not realizing that your class isn’t disposing the SemaphoreSlim and create an unmanaged resource leak.

More Related Contents:

  1. Dispose, when is it called?
  2. What happens if i return before the end of using statement? Will the dispose be called?
  3. Who Disposes of an IDisposable public property?
  4. Proper use of the IDisposable interface
  5. Use of Finalize/Dispose method in C#
  6. Is it considered acceptable to not call Dispose() on a TPL Task object?
  7. What is the difference between using IDisposable vs a destructor in C#?
  8. Disposing WPF User Controls
  9. Using statement vs. IDisposable.Dispose()
  10. Should you implement IDisposable.Dispose() so that it never throws?
  11. Proper way to dispose a new Form
  12. returning in the middle of a using block
  13. Does garbage collector call Dispose()? [duplicate]
  14. Should IDisposable.Dispose() be made safe to call multiple times?
  15. Difference between destructor, dispose and finalize method
  16. Is IDisposable.Dispose() called automatically? [duplicate]
  17. Implementing IDisposable on a subclass when the parent also implements IDisposable
  18. Is it possible to force the use of “using” for disposable classes?
  19. What does Process.Dispose() actually do?
  20. What is IDisposable for?
  21. When should I use GC.SuppressFinalize()?
  22. Who should call Dispose on IDisposable objects when passed into another object?
  23. Should I always disconnect event handlers in the Dispose method?
  24. When or if to Dispose HttpResponseMessage when calling ReadAsStreamAsync?
  25. Guidelines For Dispose() and Ninject
  26. using statement FileStream and / or StreamReader – Visual Studio 2012 Warnings
  27. What’s the purpose of GC.SuppressFinalize(this) in Dispose() method?
  28. Does SemaphoreSlim (.NET) prevent same thread from entering block?
  29. Determining if IDisposable should extend an interface or be implemented on a class implementing said interface
  30. Is it necessary to dispose System.Timers.Timer if you use one in your application?

Leave a Comment