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Marshal.CleanupUnusedObjectsInCurrentContext Method

Notifies the runtime to clean up all Runtime Callable Wrappers (RCWs) allocated in the current context.

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

public static void CleanupUnusedObjectsInCurrentContext()

The interop system pumps messages while it attempts to clean up RCWs. This ensures that cleanup for single-threaded apartment (STA) RCWs happens in all applications, including applications that do not pump often enough. However, some applications that do pump appropriately are very sensitive to where pumping occurs. When the interop system pumps messages in these applications, in places that are unexpected, , the application can encounter reentrancy issues that are difficult to diagnose. Therefore, applications need to be able to control their own pumping for a particular STA and to control the clean-up of RCWs.

However, developers often only control a subset of the threads in their application and thus cannot ensure that all threads are pumping appropriately.

To solve this problem:

  1. Use the Thread.DisableComObjectEagerCleanup method to turn off automatic cleanup of RCWs, and the message pumping that occurs, on a per-thread basis. This allows developers to opt out of automatic clean-up, and the corresponding message pumping.

  2. Use the CleanupUnusedObjectsInCurrentContext method to notify the runtime to clean up all RCWs that are allocated in the current context. This companion method allows developers to precisely control when the runtime performs cleanup in the current context.

.NET Framework

Supported in: 4

.NET Framework Client Profile

Supported in: 4

  • SecurityCriticalAttribute 

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

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.