SignalR Owin Self-Host on Linux/Mono SocketException when clients lose connection

Question

I'm running very simple signalr server self-hosted via Owin on ubuntu server 14.04, mono 3.2.8. (code below).

Connecting/Disconnecting works fine on both a remote windows server and when I deploy the bits to the linux server. But when a client dies unexpectedly instead of telling signalr that he's disconnecting, that's when I get a never-ending SocketException only on the linux server only. The windows server disconnects the client after about 30 seconds or so, but the linux server spews the socketexception (also below) every 10 seconds or so, forever.

How can I make the linux server behave like the windows server when running the same code, disconnect the user after a set timeout and not throw socketexceptions?

Server Code:

using System;
using System.Threading.Tasks;
using Microsoft.AspNet.SignalR;
using Owin;

namespace signalrtestserver
{
    class Program
    {
        static void Main(string[] args)
        {
            var uri = System.Configuration.ConfigurationManager.AppSettings["startup_uri"] ?? "http://*:7890";
            using (Microsoft.Owin.Hosting.WebApp.Start<Startup>(uri))
            {
                Console.WriteLine(string.Format("Server started on {0}. Press enter to close.", uri));
                Console.ReadLine();
            }
        }
    }

    class Startup
    {
        static Hub hub;

        public void Configuration(IAppBuilder app)
        {
            app.UseCors(Microsoft.Owin.Cors.CorsOptions.AllowAll);
            var configuration = new HubConfiguration();
            configuration.EnableDetailedErrors = true;
            app.MapSignalR("/signalr", configuration);
            hub = new MyHub();
        }
    }

    public class MyHub : Hub
    {
        public override Task OnConnected() { Console.WriteLine(Context.ConnectionId + " connected"); return base.OnConnected(); }
        public override Task OnDisconnected() { Console.WriteLine(Context.ConnectionId + " disconnected"); return base.OnDisconnected(); }
        public override Task OnReconnected() { Console.WriteLine(Context.ConnectionId + " reconnected"); return base.OnReconnected(); }
    }
}

Client Code:

using System;
using System.Net;
using Microsoft.AspNet.SignalR.Client;

namespace signalrconnection
{
    class Program
    {
        static void Main(string[] args)
        {
            var uri = System.Configuration.ConfigurationManager.AppSettings["signalr_uri"] ?? "http://localhost:7890/signalr";
            ServicePointManager.DefaultConnectionLimit = 10;
            var hubConnection = new HubConnection(uri, false);
            hubConnection.StateChanged += stateChange => Console.WriteLine(string.Format("SignalR {0} >> {1} ({2})", stateChange.OldState, stateChange.NewState, hubConnection.Transport == null ? "<<null>>" : hubConnection.Transport.Name));
            var hubProxy = hubConnection.CreateHubProxy("MyHub");
            hubConnection.Start();
            Console.WriteLine("Press enter to die...");
            Console.ReadLine();
            //hubConnection.Dispose(); //uncomment this to simulate a graceful disconnect which works on both windows and linux
        }
    }
}

Never-Ending Mono Exception:

{path-to-project}/Microsoft.AspNet.SignalR.Core.dll Error : 0 : SignalR exception thrown by Task: System.AggregateException: One or more errors occured ---> System.IO.IOException: Write failure ---> System.Net.Sockets.SocketException: Connection reset by peer
  at System.Net.Sockets.Socket.Send (System.Byte[] buf, Int32 offset, Int32 size, SocketFlags flags) [0x00000] in <filename unknown>:0
  at System.Net.Sockets.NetworkStream.Write (System.Byte[] buffer, Int32 offset, Int32 size) [0x00000] in <filename unknown>:0
  --- End of inner exception stack trace ---
  at System.Net.Sockets.NetworkStream.Write (System.Byte[] buffer, Int32 offset, Int32 size) [0x00000] in <filename unknown>:0
  at System.Net.ResponseStream.InternalWrite (System.Byte[] buffer, Int32 offset, Int32 count) [0x00000] in <filename unknown>:0
  at System.Net.ResponseStream.Write (System.Byte[] buffer, Int32 offset, Int32 count) [0x00000] in <filename unknown>:0
  at Microsoft.Owin.Host.HttpListener.RequestProcessing.ExceptionFilterStream.Write (System.Byte[] buffer, Int32 offset, Int32 count) [0x00000] in <filename unknown>:0
  --- End of inner exception stack trace ---
 --> (Inner exception 0) System.IO.IOException: Write failure ---> System.Net.Sockets.SocketException: Connection reset by peer
  at System.Net.Sockets.Socket.Send (System.Byte[] buf, Int32 offset, Int32 size, SocketFlags flags) [0x00000] in <filename unknown>:0
  at System.Net.Sockets.NetworkStream.Write (System.Byte[] buffer, Int32 offset, Int32 size) [0x00000] in <filename unknown>:0
  --- End of inner exception stack trace ---
  at System.Net.Sockets.NetworkStream.Write (System.Byte[] buffer, Int32 offset, Int32 size) [0x00000] in <filename unknown>:0
  at System.Net.ResponseStream.InternalWrite (System.Byte[] buffer, Int32 offset, Int32 count) [0x00000] in <filename unknown>:0
  at System.Net.ResponseStream.Write (System.Byte[] buffer, Int32 offset, Int32 count) [0x00000] in <filename unknown>:0
  at Microsoft.Owin.Host.HttpListener.RequestProcessing.ExceptionFilterStream.Write (System.Byte[] buffer, Int32 offset, Int32 count) [0x00000] in <filename unknown>:0

Any help would be much appreciated. Thanks in advance!

Answer 1

The problem is this line static Hub hub, and this one hub = new MyHub() in your Startup method.

You do not need to explicitly create instances of the Hub class, neither do you need to keep a reference around. The hub class is instantiated on every request to the server. See http://www.asp.net/signalr/overview/signalr-20/hubs-api/hubs-api-guide-server#transience the section on Hub object lifetime.