Well, I've finished an initial implementation of a ConcurrentList<T> data structure. It implements the IList<T> interface (partially—no Insert, RemoveAt, etc.--it is an append-only structure) and is both thread-safe and lock-free.

(I also came up with a few different ways to resolve the Count issue mentioned in my previous post; what I've settled on for now is basically the most obvious and straightforward version.)

The source code for the class itself is available to view in my GitHub repository here:

Check out the source code.

Now for the somewhat disheartening part: thus far, based on my own performance benchmarks, I see little evidence that this actually outperforms a simple List<T> with synchronized calls to Add (using, e.g., a lock statement). So that's a bit disappointing. But I figured I'd share the source code, in case some hackers out there might be able to figure out how to make it better.

Also, I feel like part of the issue I may be having is that it's tough to really create a lot of thread contention on a puny little laptop with such a lightweight method (I'd wager List<T>.Add couldn't be much more than 10 lines). So maybe if this could get tested on a 32-core server somewhere, the results would be more noteworthy. I don't know!

Anyway, at least it passes the unit tests. That's got to be worth something, right?

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