class Program
    {
        static void Main(string[] args)
        {
            var ev = new CountdownEvent(8);
            var a = DateTime.Now;
          /*  ThreadPool.QueueUserWorkItem(Pi.CountPi, new ThreadData() {Count = 1000000000, Event = ev});
            ThreadPool.QueueUserWorkItem(Pi.CountPi, new ThreadData() {Count = 1000000000, Event = ev});
            ThreadPool.QueueUserWorkItem(Pi.CountPi, new ThreadData() {Count = 1000000000, Event = ev});
            ThreadPool.QueueUserWorkItem(Pi.CountPi, new ThreadData() {Count = 1000000000, Event = ev});
            ThreadPool.QueueUserWorkItem(Pi.CountPi, new ThreadData() {Count = 1000000000, Event = ev});
            ThreadPool.QueueUserWorkItem(Pi.CountPi, new ThreadData() {Count = 1000000000, Event = ev});
            ThreadPool.QueueUserWorkItem(Pi.CountPi, new ThreadData() {Count = 1000000000, Event = ev});
            ThreadPool.QueueUserWorkItem(Pi.CountPi, new ThreadData() {Count = 1000000000, Event = ev});
            Console.WriteLine("start");
            ev.Wait();
            */

            var a1 = new Thread(Pi.CountPi);
            var a2 = new Thread(Pi.CountPi);
            var a3 = new Thread(Pi.CountPi);
            var a4 = new Thread(Pi.CountPi);
            var a5 = new Thread(Pi.CountPi);
            var a6 = new Thread(Pi.CountPi);
            var a7 = new Thread(Pi.CountPi);
            var a8 = new Thread(Pi.CountPi);
            a1.Start(new ThreadData()
            {
                Count = 1000000000, Event = ev
            });
            a2.Start(new ThreadData()
            {
                Count = 1000000000, Event = ev
            });
            a3.Start(new ThreadData()
            {
                Count = 1000000000, Event = ev
            });
            a4.Start(new ThreadData()
            {
                Count = 1000000000, Event = ev
            });
            a5.Start(new ThreadData()
            {
                Count = 1000000000, Event = ev
            });
            a6.Start(new ThreadData()
            {
                Count = 1000000000, Event = ev
            });
            a7.Start(new ThreadData()
            {
                Count = 1000000000, Event = ev
            });
            a8.Start(new ThreadData()
            {
                Count = 1000000000, Event = ev
            });
            a1.Join();
            a2.Join();
            a3.Join();
            a4.Join();
            a5.Join();
            a6.Join();
            a7.Join();
            a8.Join();

            Console.WriteLine("stop all");
            Console.WriteLine(DateTime.Now-a);
        }
    }
 public class Pi
    {
        public static void CountPi(object o)
        {
            var c = o as ThreadData;

            int d = 1;
            double pi = 0;
            for (int i = 0; i < c.Count; i++)
            {
                if (i % 2 == 0)
                    pi += 1.0 / d;
                else
                    pi -= 1.0 / d;
                d += 2;
            }

            Console.WriteLine("kek");
            c.Event.Signal();
        }
    }
 public class ThreadData
    {
        public int Count { get; set; }
        public CountdownEvent Event { get; set; }
    }