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In this question @Jon skeet referenced this old blog post by the authority Chris Brumme.
I was wondering, do I need to follow all calls to GC.SuppressFinalize(this) with a GC.KeepAlive(this) to avoid weird race conditions where a finalizer can be invoked during the time a disposer is running in heavily multithreaded applications?
If so, can you come up with a sample program that exposes this bug?
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The GC does not call Dispose , it calls your finalizer (which you should make call Dispose(false) ).
Dispose() will not be called automatically. If there is a finalizer it will be called automatically. Implementing IDisposable provides a way for users of your class to release resources early, instead of waiting for the garbage collector.
There is a simple guideline: if you have finished with an object whose type implements IDisposable then call Dispose() on it; you should use a using block to do this.
Enter GC. KeepAlive() . The purpose of GC. KeepAlive() is to force the garbage collector to treat the object as still live, thereby preventing it from being collected, and thereby preventing the finalizer from running prematurely.
No. GC.KeepAlive doesn't actually do anything; its purpose is to 'fool' the runtime into preventing a specific object from being garbage collected between the start of the method and the call to GC.KeepAlive.
Any method call will keep an object alive in this way: you could pass it to Console.WriteLine, call ToString, or even... GC.SuppressFinalize.
(Or as MSDN puts it:
The KeepAlive method performs no operation and produces no side effects other than extending the lifetime of the object passed in as a parameter.)
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I was asked this recently by a colleague, and posted the answer on my blog, along with example code:
https://blog.stephencleary.com/2009/08/q-if-dispose-calls-suppressfinalize-is.html
You may also be interested in other Disposable blog posts of mine, one of which explores when SuppressFinalize or KeepAlive() is required.
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