Simple Semaphore Usage

Usage.cs

using System;
using System.Threading;
using System.Threading.Tasks;

namespace Semaphore
{
    class Program
    {
        static void Main(string[] args)
        {
            Do();
            Console.ReadLine();
        }

        private static void Do()
        {
            var cts = new CancellationTokenSource(TimeSpan.FromSeconds(5));
            var concurrency = 10;
            var semaphore = new SemaphoreSlim(concurrency);

            Task.Run(async () =>
            {
                while (!cts.IsCancellationRequested)
                {
                    await semaphore.WaitAsync(cts.Token);

                    SimulateWork(semaphore, cts.Token).IgnoreContinuation();
                }
            });
        }

        static async Task SimulateWork(SemaphoreSlim semaphore, CancellationToken token)
        {
            try
            {
                await Task.Delay(500, token);
                Console.Write(".");
            }
            catch (OperationCanceledException)
            {
                // graceful shutdown
                Console.Write("!");
            }
            finally
            {
                semaphore.Release();
            }
        }
    }

    static class TaskExtensions
    {
        public static void IgnoreContinuation(this Task task)
        {
            task.ContinueWith(t =>
            {
                var exception = t.Exception;
                Console.Error.WriteLine(exception?.Message);
            }, TaskContinuationOptions.OnlyOnFaulted);
        }
    }
}