.NET: How does the EventHandler race-condition fix work?

Question

There\'s the following pattern which is used to avoid a race condition when raising events in case another thread unsubscribes from MyEvent, making it null.

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Answer 1

I would expect that once I got the MyEvent delegate inside the 'handler' reference, once somebody would change MyEvent that the object that 'handler' references will be changed as well. [..] Notice that System.Delegate is a class and not a struct.

Although you are correct that delegate-types are references-types, they are immutable reference-types. From System.Delegate:

"Delegates are immutable; once created, the invocation list of a delegate does not change.[...] Combining operations, such as Combine and Remove, do not alter existing delegates. Instead, such an operation returns a new delegate that contains the results of the operation, an unchanged delegate, or Nothing.

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On another note, the only issue this pattern addresses is preventing the attempted invocation of a null delegate-reference. Events are prone to races despite this "fix".