using System;

using System.Threading;

​

public static class Program

{

    public static void Main()

    {

        WeakReference timer = StartTimer();

        Console.WriteLine($"Before GC.Collect - IsAlive: {timer.IsAlive}");

        GC.Collect();

        Console.WriteLine($"After GC.Collect  - IsAlive: {timer.IsAlive}");

        Thread.Sleep(1000);

        Console.WriteLine($"Finished");

​

        static WeakReference StartTimer()

        {

            System.Threading.Timer timer = new(_ => Console.WriteLine("Callback!"), null, 500, -1);

            return new(timer);

        }

    }

}