Few changes according to code review

src/Microsoft.AspNet.Server.WebListener/AwaitableThrottle.cs

@@ -1,5 +1,5 @@
 //------------------------------------------------------------------------------
-// <copyright file="HttpListener.cs" company="Microsoft">
+// <copyright file="AwaitableThrottle.cs" company="Microsoft">
 //     Copyright (c) Microsoft Corporation.  All rights reserved.
 // </copyright>
 //------------------------------------------------------------------------------
@@ -13,7 +13,7 @@ namespace Microsoft.AspNet.Server.WebListener
     /// <summary>
     /// Awaitable object that acts like a semaphore. The object would wait if more than maxConcurrent number of clients waits on it
     /// </summary>
-    public class AwaitableThrottle
+    internal class AwaitableThrottle
     {
         private static readonly TaskAwaiter<bool> CompletedAwaiter = Task.FromResult(true).GetAwaiter();
 

src/Microsoft.AspNet.Server.WebListener/OwinWebListener.cs

@@ -500,6 +500,8 @@ namespace Microsoft.AspNet.Server.WebListener
                 }
                 catch (Exception ex)
                 {
+                    // Request processing failed to be queued in threadpool
+                    // Log the error message, release throttle and move on
                     LogHelper.LogException(_logger, "ProcessRequestAsync", ex);
                     _requestProcessingThrottle.Release();
                 }