using System;

using System.Threading;

using System.Collections.Generic;

using System.Threading.Tasks;

​

public static class Program

{

    public static void Main()

    {

        List<Task> tasks = new List<Task>();

        for (int index = 0; index < 10; index++)

        {

            tasks.Add(Task.Factory.StartNew(() => Console.WriteLine(TestObject.Instance.GetMessage())));

        }

​

        Task.WaitAll(tasks.ToArray());

        Console.WriteLine();

        Console.WriteLine("Completed...");

    }

}

​

public class TestObject

{

    private static TestObject pInstance;

    private readonly static Mutex pInstanceMutex = new Mutex(false);

    private readonly object pMsgLock = new Object();

    private readonly Random pRandom;

    public static TestObject Instance

    {

        get

        {

            try

            {

                pInstanceMutex.WaitOne();

                pInstance ??= new TestObject();

                Thread.Sleep(pInstance.GetRandomDelay());

                return pInstance;

            }

            finally

            {

                pInstanceMutex.ReleaseMutex();

            }

        }

    }

​

    public string GetMessage()

    {

        lock (pMsgLock)

        {

            string Result = "Message from Thread: " + Environment.CurrentManagedThreadId;

            return Result;

        }

    }

    private TimeSpan GetRandomDelay()

    {

        try

        {

            Monitor.Enter(pRandom);

            int randomValue = pRandom.Next(50,300);

            TimeSpan Result = TimeSpan.FromMilliseconds(randomValue); 

            return Result;

        }

        finally

        {

            Monitor.Exit(pRandom);

        }

    }

​

    private TestObject()

    {

        pRandom = new Random();

        Console.WriteLine("TestObject created by Thread: " + Environment.CurrentManagedThreadId);

    }

}