Fixed shutdown hanging

- Added Stopping event to KestrelThread so that
incoming connections get a chance to gracefully close
before disposing the event loop
- Call _post.Dispose instead of UnReference. Sometimes
Dispose would happen on the finalizer thread and _queueCloseHandle
would be null.

#9

Author: davidfowl

src/Microsoft.AspNet.Server.Kestrel/Http/Connection.cs

@@ -61,6 +61,8 @@ public Connection(ListenerContext context, UvStreamHandle socket) : base(context
         {
             _socket = socket;
             ConnectionControl = this;
+
+            Thread.OnStopping += OnLoopStopping;
         }
 
         public void Start()
@@ -73,6 +75,11 @@ public void Start()
             _socket.ReadStart(_allocCallback, _readCallback, this);
         }
 
+        private void OnLoopStopping()
+        {
+            _socket.Dispose();
+        }
+
         private Libuv.uv_buf_t OnAlloc(UvStreamHandle handle, int suggestedSize)
         {
             return handle.Libuv.buf_init(

src/Microsoft.AspNet.Server.Kestrel/Infrastructure/KestrelThread.cs

@@ -26,6 +26,7 @@ public class KestrelThread
         Queue<CloseHandle> _closeHandleRunning = new Queue<CloseHandle>();
         object _workSync = new Object();
         bool _stopImmediate = false;
+        volatile bool _aborting = false;
         private ExceptionDispatchInfo _closeError;
 
         public KestrelThread(KestrelEngine engine)
@@ -41,6 +42,8 @@ public KestrelThread(KestrelEngine engine)
 
         public Action<Action<IntPtr>, IntPtr> QueueCloseHandle { get; internal set; }
 
+        public event Action OnStopping;
+
         public Task StartAsync()
         {
             var tcs = new TaskCompletionSource<int>();
@@ -61,6 +64,7 @@ public void Stop(TimeSpan timeout)
 #endif
                 }
             }
+
             if (_closeError != null)
             {
                 _closeError.Throw();
@@ -69,7 +73,13 @@ public void Stop(TimeSpan timeout)
 
         private void OnStop(object obj)
         {
-            _post.Unreference();
+            if (OnStopping != null)
+            {
+                OnStopping();
+            }
+            
+            _aborting = true;
+            _post.Dispose();
         }
 
         private void OnStopImmediate(object obj)
@@ -80,6 +90,11 @@ private void OnStopImmediate(object obj)
 
         public void Post(Action<object> callback, object state)
         {
+            if (_aborting)
+            {
+                return;
+            }
+
             lock (_workSync)
             {
                 _workAdding.Enqueue(new Work { Callback = callback, State = state });
@@ -130,19 +145,6 @@ private void ThreadStart(object parameter)
                     return;
                 }
 
-                // run the loop one more time to delete the open handles
-                _post.Reference();
-                _post.DangerousClose();
-                _engine.Libuv.walk(
-                    _loop,
-                    (ptr, arg) =>
-                    {
-                        var handle = UvMemory.FromIntPtr<UvHandle>(ptr);
-                        handle.Dispose();
-                    },
-                    IntPtr.Zero);
-                var ran2 = _loop.Run();
-
                 _loop.Dispose();
             }
             catch (Exception ex)