using System;

using System.Reactive.Linq;

​

public class Program

{

    public static void Main()

    {

        Observable

            .Generate(0, _ => true, x => x, x => x, _ => TimeSpan.FromMilliseconds(10))

            .Select(_ => Observable

                .Return(DateTime.Now)

                .Do(d => Console.WriteLine(

                    "Then: {0:HH:mm:ss.fff}, " +

                    "Now: {1:HH:mm:ss.fff}, " +

                    "TotalMemory: {2:#,0} bytes", d, DateTime.Now, GC.GetTotalMemory(true)))

                .Delay(TimeSpan.FromMilliseconds(1000)))

            .Merge(maxConcurrent: 1)

            .Take(9)

            .Wait();

    }

}

​