Adding an IKestralServerInformation.ThreadCount property

Will default to 1 until multi-loop stability is ensured

src/Kestrel/IKestrelServerInformation.cs

@@ -0,0 +1,10 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+namespace Kestrel
+{
+    public interface IKestrelServerInformation
+    {
+        int ThreadCount { get; set; }
+    }
+}

src/Kestrel/ServerFactory.cs

@@ -38,7 +38,7 @@ namespace Kestrel
             var disposables = new List<IDisposable>();
             var information = (ServerInformation)serverInformation;
             var engine = new KestrelEngine(_libraryManager, _appShutdownService);
-            engine.Start(Environment.ProcessorCount);
+            engine.Start(information.ThreadCount == 0 ? 1 : information.ThreadCount);
             foreach (var address in information.Addresses)
             {
                 disposables.Add(engine.CreateServer(

src/Kestrel/ServerInformation.cs

@@ -8,7 +8,7 @@ using Microsoft.Framework.Configuration;
 
 namespace Kestrel
 {
-    public class ServerInformation : IServerInformation
+    public class ServerInformation : IServerInformation, IKestrelServerInformation
     {
         public ServerInformation()
         {
@@ -25,7 +25,7 @@ namespace Kestrel
             foreach (var url in urls.Split(new[] { ';' }, StringSplitOptions.RemoveEmptyEntries))
             {
                 var address = ServerAddress.FromUrl(url);
-                if(address != null)
+                if (address != null)
                 {
                     Addresses.Add(address);
                 }
@@ -41,5 +41,7 @@ namespace Kestrel
         }
 
         public IList<ServerAddress> Addresses { get; private set; }
+
+        public int ThreadCount { get; set; }
     }
 }