Paralel.Invoke in C#

using System;
using System.Threading;
using System.Diagnostics;
using System.Threading.Tasks;

namespace SgartParallelInvoke
{
  class Program
  {
    static void Main(string[] args)
    {
      Stopwatch timer = new Stopwatch();
      string param = "esempio di passaggio parametri";
      timer.Start();

      Parallel.Invoke(
        delegate() { DoWork(1); },
        delegate() { DoWorkA(2); },
        delegate() { DoWorkA(3); },
        delegate() { DoWork(4); },
        delegate() { DoWork(5); },
        delegate() { DoWorkB(6, param); },
        delegate() { DoWorkA(7); },
        delegate() { DoWork(8); },
        delegate() { DoWorkB(9, param); }
      );

      timer.Stop();

      Console.WriteLine(string.Format("\nFinished...\nTotal time: {0}"
        , timer.Elapsed));
      Console.ReadKey(true);
    }

    static void DoWork(int i)
    {
      int pause = 500000000;
      Console.WriteLine(string.Format("{0} begin", i));
      Thread.SpinWait(pause);
      Console.WriteLine(string.Format("{0} end", i));
    }

    static void DoWorkA(int i)
    {
      int pause = 400000000;
      Console.WriteLine(string.Format("{0} begin A", i));
      Thread.SpinWait(pause);
      Console.WriteLine(string.Format("{0} end A", i));
    }

    static void DoWorkB(int i, string param)
    {
      int pause = 450000000;
      Console.WriteLine(string.Format("{0} begin B - param: {1}", i, param));
      Thread.SpinWait(pause);
      Console.WriteLine(string.Format("{0} end B", i));
    }
  }
}