RxTimer

gistfile1.cs

using System;
using System.Reactive.Linq;
using System.Threading.Tasks;

namespace RxTimer
{
    class Program
    {
        static void Main(string[] args)
        {
            var isBusy = false;
            var interval = Observable.Interval(TimeSpan.FromSeconds(1));

            interval.Where(x => !isBusy)
             .Subscribe(async (item) =>
             {
                 isBusy = true;

                 Console.WriteLine("Doing some background work: {0}", DateTime.UtcNow);

                 await Task.Delay(TimeSpan.FromSeconds(2));

                 Console.WriteLine("Done doing some background work: {0}", DateTime.UtcNow);

                 isBusy = false;
             });

            Console.ReadLine();
        }
    }
}