C#

public void Post(SendOrPostCallback sendOrPostCallback)
{
    // ...
}

public void Post(MethodInvoker methodInvoker)
{
    // ...
}

private static List<Thread> threads = new List<Thread> (0);
private static List<ThreadMethod> methods = new List<ThreadMethod>(0);

public delegate void xCO_Method(); delegate void CallBack(Thread T);
static private xCO_Method Method; static private CallBack CallBackMethod;

public static void Start(xCO_Method method, object[] args)
{
    int cpu = System.Environment.ProcessorCount;
    Method = method;
    CallBackMethod = new CallBack(Completed);

    for (int i = 0; i < cpu; i++)
    {
        methods.Add(new ThreadMethod());
        threads.Add(new Thread(methods[i].Work));
        threads[i].Name = i.ToString();
    }

    foreach (Thread T in threads)
        T.Start(args[i]);
}

private class ThreadMethod
{
    public object[] Result;
    public void Work()
    { 
        //Do Work
        Method.Invoke(args);
    
        //CallBack
        CallBackMethod.Invoke(Thread.CurrentThread);
    }
}

private static void Completed(Thread T)
{
    Console.WriteLine("Thread " + T.Name + " ended");
}