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MSDN Library

Marshal.AreComObjectsAvailableForCleanup Method

Indicates whether runtime callable wrappers (RCWs) from any context are available for cleanup.

Namespace:  System.Runtime.InteropServices
Assemblies:   System.Runtime.InteropServices (in System.Runtime.InteropServices.dll)
  mscorlib (in mscorlib.dll)

public static bool AreComObjectsAvailableForCleanup()

Return Value

Type: System.Boolean
true if there are any RCWs available for cleanup; otherwise, false.

If there are a lot of references between managed and native code with deep dependency graphs it can take a long time for all the objects to clean up. Each time a GC runs it will free up some number of RCWs, which will in turn release the underlying COM objects. Those COM objects will then release their managed references and make more objects available for cleanup the next time a GC runs, which starts the process over again.

The AreComObjectsAvailableForCleanup method provides a way for the application to determine how many cycles of GC.Collect and GC.WaitForPendingFinalizers need to happen in order to clean everything up.

.NET Framework

Supported in: 4.6, 4.5, 4

.NET Framework Client Profile

Supported in: 4

.NET for Windows Phone apps

Supported in: Windows Phone 8.1

Portable Class Library

Supported in: Portable Class Library

  • SecurityCriticalAttribute 

    requires full trust for the immediate caller. This member cannot be used by partially trusted or transparent code.

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