Singleton и многопоточность

using System;
using System.Threading;
using System.Linq;

class Program
{
   static void Main(string[] args)
   {
        (new Thread(() =>
    {
        var comp2 = new Computer();
        comp2.OS = OS.GetInstance("Windows 10");
        Console.WriteLine(comp2.OS.Name);

    })).Start();

        (new Thread(() =>
    {
        var comp2 = new Computer();
        comp2.OS = OS.GetInstance("Windows xp");
        Console.WriteLine(comp2.OS.Name);

    })).Start();

    Console.ReadLine();
   }
}

class Computer
{
    public OS OS {get;set;}

    public void Launch(string osName)
    {
        this.OS = OS.GetInstance(osName);
    }
}

class OS
{
    private static OS instance;

    public static object syncRoot = new object();

    public string Name{get; private set;}

    protected OS(string name)
    {
        this.Name = name;
    }

    public static OS GetInstance(string name)
    {
        if(instance == null)
        {
            lock(syncRoot)
            {
                if(instance == null)
                {
                    instance = new OS(name);
                }
            }
        }
        return instance;
    }
}