using System;

using System.Threading;

​

class Program

    {

        class Singleton

        {

            private Singleton() { }

​

            private static Singleton _instance;

​

            private static readonly object _lock = new object();

​

            public static Singleton GetInstance(string value)

            {

                if (_instance == null)

                {

                    lock (_lock)

                    {

                        if (_instance == null)

                        {

                            _instance = new Singleton();

                            _instance.Value = value;

                        }

                    }

                }

                return _instance;

            }

            public string Value { get; set; }

        }

​

        static void Main(string[] args)

        {

​

            Thread process1 = new Thread(() =>

            {

                TestSingleton("Object 1");

            });

            Thread process2 = new Thread(() =>

            {

                TestSingleton("Object 2");

            });

​

            process1.Start();

            process2.Start();

​

            process1.Join();

            process2.Join();

​

            Console.ReadKey();

        }

​

        public static void TestSingleton(string value)

        {

            Singleton singleton = Singleton.GetInstance(value);

            Console.WriteLine(singleton.Value);

        }

    }