using System;

using System.Threading;

​

​

public class Program

{

    private static readonly object _lock = new object();

    public static void Main()

    {

        //Console.WriteLine("Start");

        for (var i = 0; i < 10; i++)

        {

            //Console.WriteLine("Start "+i); 

            System.Threading.Thread thread = new System.Threading.Thread(() => ExecuteInBackground(i));

            thread.IsBackground = true;

            thread.Start();

        }

        //Console.WriteLine("End");

        //Console.ReadLine();

    }

​

    private static void ExecuteInBackground(Object obj)

    {

        lock (_lock)

        {

            //Thread.Sleep(10);

            Console.WriteLine("A "+obj);

            test.ttt(obj);

        }

    }

}

​

​

public static class test

{

    public static void ttt(object obj)

    {

        Console.WriteLine("B "+ obj);

    }

}