QUESTION: Why does not this program quit when compiled in Release mode?

The following works as expected when building in Debug – the execution is done after three seconds. But, for some reason, it fails when in Release.

class Program
{
    static void Main(string[] args)
    {
        var w = new Worker();
        while (!w.IsDone);
        Console.WriteLine("The work is done.");
    }
}

class Worker
{
    public bool IsDone;

    public Worker()
    {
        var thread = new Thread(Job);
        thread.Start();
    }

    private void Job()
    {
        Thread.Sleep(3000);
        IsDone = true;
    }
}

Could you explain what is happening? How could you fix it?

Tomorrow, I will share the answer.