Workaround for the WaitHandle.WaitAll 64 handle limit?

Question

My application spawns loads of different small worker threads via ThreadPool.QueueUserWorkItem which I keep track of via multiple ManualResetEvent

Answer 1

Adding to dtb's answer you can wrap this into a nice simple class.

public class Countdown : IDisposable
{
    private readonly ManualResetEvent done;
    private readonly int total;
    private long current;

    public Countdown(int total)
    {
        this.total = total;
        current = total;
        done = new ManualResetEvent(false);
    }

    public void Signal()
    {
        if (Interlocked.Decrement(ref current) == 0)
        {
            done.Set();
        }
    }

    public void Wait()
    {
        done.WaitOne();
    }

    public void Dispose()
    {
        ((IDisposable)done).Dispose();
    }
}