Pool DefaultHttpContext [Design]

src/Microsoft.AspNet.Hosting.Server.Abstractions/IServerFactory.cs

@@ -11,6 +11,6 @@ namespace Microsoft.AspNet.Hosting.Server
     public interface IServerFactory
     {
         IFeatureCollection Initialize(IConfiguration configuration);
-        IDisposable Start(IFeatureCollection serverFeatures, Func<IFeatureCollection, Task> application);
+        IDisposable Start(IFeatureCollection serverFeatures, Func<IFeatureCollection, Task<IDisposable>> application);
     }
 }

src/Microsoft.AspNet.Hosting/Builder/HttpContextFactory.cs

@@ -1,6 +1,8 @@
 // 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.
 
+using System;
+using System.Collections.Concurrent;
 using Microsoft.AspNet.Http;
 using Microsoft.AspNet.Http.Features;
 using Microsoft.AspNet.Http.Internal;
@@ -9,9 +11,47 @@ namespace Microsoft.AspNet.Hosting.Builder
 {
     public class HttpContextFactory : IHttpContextFactory
     {
+        private static int _capacity = 32 * Environment.ProcessorCount;
+        private static readonly ConcurrentQueue<DefaultHttpContext> _contextPool = new ConcurrentQueue<DefaultHttpContext>();
+        private static readonly ConcurrentQueue<FeatureCollection> _featureCollectionPool = new ConcurrentQueue<FeatureCollection>();
+
         public HttpContext CreateHttpContext(IFeatureCollection featureCollection)
         {
-            return new DefaultHttpContext(new FeatureCollection(featureCollection));
+            DefaultHttpContext context;
+            if (_contextPool.TryDequeue(out context))
+            {
+                context.Initalize(CreateFeatureCollection(featureCollection));
+                return context;
+            }
+            return new DefaultHttpContext(CreateFeatureCollection(featureCollection), PoolContext);
+        }
+
+        internal FeatureCollection CreateFeatureCollection(IFeatureCollection innerFeatureCollection)
+        {
+            FeatureCollection featureCollection;
+            if (_featureCollectionPool.TryDequeue(out featureCollection))
+            {
+                featureCollection.Reset(innerFeatureCollection);
+                return featureCollection;
+            }
+            return new FeatureCollection(innerFeatureCollection, PoolFeatureCollection);
+        }
+
+        internal void PoolContext(DefaultHttpContext context)
+        {
+            // Benign race condition
+            if (_contextPool.Count < _capacity)
+            {
+                _contextPool.Enqueue(context);
+            }
+        }
+        internal void PoolFeatureCollection(FeatureCollection context)
+        {
+            // Benign race condition
+            if (_featureCollectionPool.Count < _capacity)
+            {
+                _featureCollectionPool.Enqueue(context);
+            }
         }
     }
 }

src/Microsoft.AspNet.Hosting/Internal/HostingEngine.cs

@@ -71,6 +71,7 @@ public virtual IDisposable Start()
                 async features =>
                 {
                     var httpContext = contextFactory.CreateHttpContext(features);
+
                     httpContext.ApplicationServices = _applicationServices;
                     var requestIdentifier = GetRequestIdentifier(httpContext);
 
@@ -79,6 +80,8 @@ public virtual IDisposable Start()
                         contextAccessor.HttpContext = httpContext;
                         await application(httpContext);
                     }
+
+                    return httpContext;
                 });
 
             _applicationLifetime.NotifyStarted();

src/Microsoft.AspNet.Hosting/project.json

@@ -26,7 +26,8 @@
         "dnx451": { },
         "dnxcore50": {
             "dependencies": {
-                "System.Console": "4.0.0-beta-*"
+                "System.Console": "4.0.0-beta-*",
+                "System.Collections.Concurrent": "4.0.11-beta-*"
             }
         }
     }