FinalizerSample.cs

using System;
using System.Threading;

namespace ConsoleApplication1
{
    internal class Program
    {
        private class A
        {
            ~A()
            {
                Console.WriteLine("  Finalizer called;");
            }
        }

        // IMPORTANT: run release build without debugging (Ctrl-F5 to launch)
        private static void Main()
        {
            var x = new A();
            var r = new WeakReference(x);
            GC.Collect();
            GC.Collect();
            Console.WriteLine("object at gc gen" + GC.GetGeneration(x));
            GC.KeepAlive(x);

            // x is available for collection now;
            Console.WriteLine("before GC0, alive? " + r.IsAlive);
            GC.Collect(0);
            Console.WriteLine("before GC1, alive? " + r.IsAlive);
            GC.Collect(1);
            Console.WriteLine("before GC2, alive? " + r.IsAlive);
            GC.Collect(2);
            Console.WriteLine("after GC2,  alive? " + r.IsAlive);

            Thread.Sleep(500);

            Console.WriteLine("After 500ms idle");

            GC.WaitForPendingFinalizers();

            Console.WriteLine("Done");
            Console.ReadKey();
        }
    }
}