QueueExecution.cs

using System;
using System.Threading;

namespace ConsoleApplication11
{
    internal class Program
	{
		private static void Main(string[] args)
		{
			for (int i = 0; i < 50; i++)
			{
				ThreadPool.QueueUserWorkItem(Handler, i);
			}

			Console.ReadLine();
		}

		private static void Handler(object state)
		{
			Execute((int)state);
		}

		private static void Execute(int i)
		{
			int index = i;

			Thread.Sleep((new Random(100)).Next(1000));

			Console.WriteLine(index.ToString());
		}
	}
}