using System;

using System.Collections.Concurrent;

using System.Threading.Tasks;

​

public class Program

{

    public class BaseClass

    {

        public static ConcurrentDictionary<Type, int> Counter = new ConcurrentDictionary<Type, int>();

        public BaseClass()

        {

            Counter.AddOrUpdate(GetType(), 1, (type, i) => i + 1);

        }

    }

​

    public class A : BaseClass

    {

    }

​

    public class B : A

    {

    }

​

    public class C : A

    {

    }

​

    public static void Main(string[] args)

    {

        var t1 = Task.Run(() =>

        {

            for (var i = 0; i < 2; i++)

            {

                Console.WriteLine("Creating " + new A());

            }

        }

​

        );

        var t2 = Task.Run(() =>

        {

            for (var i = 0; i < 4; i++)

            {

                Console.WriteLine("Creating " + new B());

            }

        }

​

        );

        var t3 = Task.Run(() =>

        {

            for (var i = 0; i < 1; i++)

            {

                Console.WriteLine("Creating " + new C());

            }

        }

​

        );

        Task.WaitAll(t1, t2, t3);

        foreach (var item in BaseClass.Counter.Keys)

        {

            Console.WriteLine(item + " " + BaseClass.Counter[item]);

        }

    }

}