runtime: BufferBlock slow?

Just chiming in… if ConcurrentQueue works for your needs, then go ahead and use it. You won’t get much faster than that.

BlockingCollection provides an abstraction over a concurrent collection (defaulting to ConcurrentQueue) that allows producers/consumers to wait for a notfull/notempty signal. AsyncCollection provides (almost) the same abstraction over a concurrent collection (defaulting to ConcurrentQueue) that allows producers/consumers to asynchronously wait for a notfull/notempty signal.

If you don’t need the signals, then you don’t need that abstraction, and can just use ConcurrentQueue directly.

BufferBlock is a much more “batteries included” type of queue. Neither BufferBlock nor BlockingCollection / AsyncCollection attempt to compare performance-wise with ConcurrentQueue, but they bring their own different advantages.

I think he’s referring to the speed of ConcurrentQueue since the default underlying collection of AsyncCollection is … wait for it… a ConcurrentQueue

Yes, but as with any component A that layers functionality over B, A is going to be more expensive, e.g.

using Nito.AsyncEx;
using System;
using System.Collections.Concurrent;
using System.Diagnostics;

class Program
{
    static void Main()
    {
        const int Iters = 1000000;
        var sw = new Stopwatch();

        while (true)
        {
            var ac = new AsyncCollection<int>();
            sw.Restart();
            for (int i = 0; i < Iters; i++)
            {
                ac.Add(i);
                ac.Take();
            }
            sw.Stop();
            Console.WriteLine("AC: " + sw.Elapsed);

            var cq = new ConcurrentQueue<int>();
            sw.Restart();
            for (int i = 0; i < Iters; i++)
            {
                cq.Enqueue(i);
                cq.TryDequeue(out int _);
            }
            sw.Stop();
            Console.WriteLine("CQ: " + sw.Elapsed);

            Console.WriteLine();
        }
    }
}

yields results like:

AC: 00:00:00.8890268
CQ: 00:00:00.0198012

This isn’t a slight against AsyncCollection; anything that layered on such functionality would incur cost. I’m just highlighting why I wrote what I wrote.