Action kullanarak multi thread sql update

using System;
using System.Collections.Generic;
using System.Data;
using System.Data.SqlClient;
using System.Linq;
using System.Text;
using System.Threading;

namespace caThreadSqlUpdate
{
    class Program
    {
        private static SqlConnection cnn = new SqlConnection("Data Source=10.130.214.200,8585;Initial Catalog=ERecete;User Id=kullanici;Password=sifre;");
        static void Main(string[] args)
        {
            if (cnn.State != ConnectionState.Open)
            {
                cnn.Open();
            }

            SqlCommand cmd = cnn.CreateCommand();
            cmd.CommandText = "select ereceteIlacListe_id,barkod FROM dbo.EReceteIlacListesi";
            SqlDataAdapter da = new SqlDataAdapter(cmd);
            DataSet ds = new DataSet();
            da.Fill(ds);

            Dictionary<IAsyncResult, Action<int, string>> li = new Dictionary<IAsyncResult, Action>();
            int i = 0;
            foreach (DataRow row in ds.Tables[0].Rows)
            {
                i++;
                Action<int, string> act = f_BarkodGuncelle;
                IAsyncResult ai = act.BeginInvoke((int)row[0], (string)row[1], delegate { Console.WriteLine("Bitti: " + row[0] + " ve " + row[1]); }, null);
                li.Add(ai, act);
                if (i == 5)
                {
                    break;
                }
            }
            while (true)
            {
                foreach (var key in li.Keys)
                {
                    if (key.IsCompleted && li[key] == null)
                    {
                        Console.WriteLine("End invoke çağırdım");
                        li[key].EndInvoke(key);
                        li[key] = null;
                    }
                }
                Thread.Sleep(1000);
            }

        }

        static public void f_BarkodGuncelle(int _iIlacId, string _sBarkod)
        {
            SqlCommand cmd = cnn.CreateCommand();
            cmd.CommandText = String.Format("UPDATE dbo.yedekEReceteIlaclari SET barkod={0} WHERE refEreceteIlacListe_id={1} ", _sBarkod, _iIlacId);
            cmd.ExecuteNonQuery();
        }
    }
}