public class Singleton
{
        private static Singleton instance;
        private static readonly object threadlock = new Object(); 

        private string Name;

        private Singleton(String name)
        {
           Name = name;
        }

        public static Singleton getInstance(string name)
        {
             if(instance == null)
	     {
		    lock(threadlock) 
		   {
		        instance = new Singleton(name);
		   }
	    }
            return instance; 
        }

        public void Print()
        {
           Console.WriteLine(Name);
        }
 }

 static void Main(string[] args)
{
            //Дополнительный поток (поток2)
             (new Thread(() =>
                {
                    var obj1 = Singleton.getInstance("obj1");
                        obj1.Print();
            
                })).Start();

            //Основной поток (поток1)
            var obj2 = Singleton.getInstance("obj2");
            obj2.Print();
}