KestrelTimeout.cs

using System;
using System.Net.Http;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Http;

namespace KestrelTimeout
{
    class Program
    {
        static void Main(string[] args)
        {
            var webhost = new WebHostBuilder()
                .UseKestrel()
                .UseSockets()
                .UseUrls("http://*:9000")
                .UseStartup<Startup>()
                .Build();

            webhost.Start();

            Task.Run(Client);

            Console.ReadLine();
        }

        static void Client()
        {
            int id = 0;

            var httpClient = new HttpClient();

            while (true)
            {
                try
                {
                    var currentId = Interlocked.Increment(ref id);

                    var request = new HttpRequestMessage { RequestUri = new Uri("http://localhost:9000/") };
                    request.Headers.Add("id", currentId.ToString()); // Send the id in the header

                    var response = await httpClient.SendAsync(request);
                    var content = await response.Content.ReadAsByteArrayAsync();

                    if (content.Length >= 4)
                    {
                        var responseId = BitConverter.ToInt32(content);

                        // Check that we got the same id back
                        if (currentId != responseId)
                        {
                            Console.WriteLine("Id mismatch! {0}, {1}", currentId, responseId);
                        }
                    }
                }
                catch
                {
                }
            }
        }
    }

    class Startup
    {
        public void Configure(IApplicationBuilder app)
        {
            app.Run(ProcessRequest);
        }

        private Random _rnd = new Random();

        private int GetNext()
        {
            lock (_rnd) return _rnd.Next(0, 100) - 50;
        }

        private async Task ProcessRequest(HttpContext context)
        {
            var timeout = Task.Delay(200 + GetNext());
            var process = Task.Run(() => HandleRequest(context));

            var t = await Task.WhenAny(timeout, process);

            if (t == timeout)
            {
                // In case of timeout, set the status code and return
                context.Response.StatusCode = 503;
            }
        }

        private void HandleRequest(HttpContext context)
        {
            // Read the id early on
            var id = context.Request.Headers["id"];

            // Simulate some processing
            Thread.Sleep(200 + GetNext());
            
            // Reply with the same id. 
            // At this point, if ProcessRequest already returned, context.Response can be the response of the next request!
            context.Response.Body.Write(BitConverter.GetBytes(int.Parse(id))); 
        }
    }
}