Finalize Method

[This documentation is for preview only, and is subject to change in later releases. Blank topics are included as placeholders.]

Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection.

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

protected virtual void Finalize()

The Finalize method is used to perform cleanup operations on unmanaged resources held by the current object before the current object is destroyed. The method is protected and therefore is accessible only through this class or through a derived class.

This method is automatically called after an object becomes inaccessible, unless the object has been exempted from finalization by a call to GC..::..SuppressFinalize. During shutdown of an application domain, Finalize is automatically called on objects that are not exempt from finalization, even those that are still accessible. Finalize is automatically called only once on a given instance, unless the object is re-registered using a mechanism such as GC..::..ReRegisterForFinalize and GC..::..SuppressFinalize has not been subsequently called.

Every implementation of Finalize in a derived type must call its base type's implementation of Finalize. This is the only case in which application code is allowed to call Finalize.

Finalize operations have the following limitations:

  • The exact time when the finalizer executes during garbage collection is undefined. Resources are not guaranteed to be released at any specific time, unless calling a Close method or a Dispose method.

  • The finalizers of two objects are not guaranteed to run in any specific order, even if one object refers to the other. That is, if Object A has a reference to Object B and both have finalizers, Object B might have already finalized when the finalizer of Object A starts.

  • The thread on which the finalizer is run is unspecified.

The Finalize method might not run to completion or might not run at all in the following exceptional circumstances:

  • Another finalizer blocks indefinitely (goes into an infinite loop, tries to obtain a lock it can never obtain and so on). Because the runtime attempts to run finalizers to completion, other finalizers might not be called if a finalizer blocks indefinitely.

  • The process terminates without giving the runtime a chance to clean up. In this case, the runtime's first notification of process termination is a DLL_PROCESS_DETACH notification.

The runtime continues to Finalize objects during shutdown only while the number of finalizable objects continues to decrease.

If Finalize or an override of Finalize throws an exception, and the runtime is not hosted by an application that overrides the default policy, the runtime terminates the process and no active try-finally blocks or finalizers are executed. This behavior ensures process integrity if the finalizer cannot free or destroy resources.

Show: