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GC.KeepAlive Method

References the specified object, which makes it ineligible for garbage collection from the start of the current routine to the point where this method is called.

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

static member KeepAlive : 
        obj:Object -> unit 

Parameters

obj
Type: System.Object
The object to reference.

The purpose of the KeepAlive method is to ensure the existence of a reference to an object that is at risk of being prematurely reclaimed by the garbage collector. A common scenario where this might happen is when there are no references to the object in managed code or data, but the object is still in use in unmanaged code such as Win32 APIs, unmanaged DLLs, or methods using COM.

This method references the obj parameter, making that object ineligible for garbage collection from the start of the routine to the point, in execution order, where this method is called. Code this method at the end, not the beginning, of the range of instructions where obj must be available.

The KeepAlive method performs no operation and produces no side effects other than extending the lifetime of the object passed in as a parameter.

The following code example creates an object at the beginning of its Main method and does not refer to the object again until the end, when the KeepAlive method is called. The object persists for the 30-second duration of the Main method, despite calls to the Collect and WaitForPendingFinalizers methods.

No code example is currently available or this language may not be supported.

.NET Framework

Supported in: 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, 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.
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