Use System.Buffers for JSON.NET

src/Microsoft.AspNet.Mvc.Formatters.Json/Internal/JsonArrayPool.cs

@@ -0,0 +1,39 @@
+// 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.Buffers;
+using Newtonsoft.Json;
+
+namespace Microsoft.AspNet.Mvc.Formatters.Json.Internal
+{
+    public class JsonArrayPool<T> : IArrayPool<T>
+    {
+        private readonly ArrayPool<T> _inner;
+
+        public JsonArrayPool(ArrayPool<T> inner)
+        {
+            if (inner == null)
+            {
+                throw new ArgumentNullException(nameof(inner));
+            }
+
+            _inner = inner;
+        }
+
+        public T[] Rent(int minimumLength)
+        {
+            return _inner.Rent(minimumLength);
+        }
+
+        public void Return(T[] array)
+        {
+            if (array == null)
+            {
+                throw new ArgumentNullException(nameof(array));
+            }
+
+            _inner.Return(array);
+        }
+    }
+}

src/Microsoft.AspNet.Mvc.Formatters.Json/Internal/MvcJsonMvcOptionsSetup.cs

@@ -1,6 +1,7 @@
 // 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.Buffers;
 using Microsoft.AspNet.Mvc.ModelBinding.Validation;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
@@ -12,22 +13,26 @@ namespace Microsoft.AspNet.Mvc.Formatters.Json.Internal
 {
     public class MvcJsonMvcOptionsSetup : ConfigureOptions<MvcOptions>
     {
-        public MvcJsonMvcOptionsSetup(ILoggerFactory loggerFactory, IOptions<MvcJsonOptions> jsonOptions)
+        public MvcJsonMvcOptionsSetup(
-            : base((_) => ConfigureMvc(_, jsonOptions.Value.SerializerSettings, loggerFactory))
+            ILoggerFactory loggerFactory,
+            IOptions<MvcJsonOptions> jsonOptions,
+            ArrayPool<char> charPool)
+            : base((options) => ConfigureMvc(options, jsonOptions.Value.SerializerSettings, loggerFactory, charPool))
         {
         }
 
         public static void ConfigureMvc(
             MvcOptions options,
             JsonSerializerSettings serializerSettings,
-            ILoggerFactory loggerFactory)
+            ILoggerFactory loggerFactory,
+            ArrayPool<char> charPool)
         {
             var jsonInputLogger = loggerFactory.CreateLogger<JsonInputFormatter>();
             var jsonInputPatchLogger = loggerFactory.CreateLogger<JsonPatchInputFormatter>();
 
-            options.OutputFormatters.Add(new JsonOutputFormatter(serializerSettings));
+            options.OutputFormatters.Add(new JsonOutputFormatter(serializerSettings, charPool));
-            options.InputFormatters.Add(new JsonInputFormatter(jsonInputLogger, serializerSettings));
+            options.InputFormatters.Add(new JsonInputFormatter(jsonInputLogger, serializerSettings, charPool));
-            options.InputFormatters.Add(new JsonPatchInputFormatter(jsonInputPatchLogger, serializerSettings));
+            options.InputFormatters.Add(new JsonPatchInputFormatter(jsonInputPatchLogger, serializerSettings, charPool));
             
             options.FormatterMappings.SetMediaTypeMappingForFormat("json", MediaTypeHeaderValue.Parse("application/json"));
 

src/Microsoft.AspNet.Mvc.Formatters.Json/JsonInputFormatter.cs

@@ -2,7 +2,9 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
+using System.Buffers;
 using System.Threading.Tasks;
+using Microsoft.AspNet.Mvc.Formatters.Json.Internal;
 using Microsoft.AspNet.Mvc.Formatters.Json.Logging;
 using Microsoft.AspNet.Mvc.Internal;
 using Microsoft.AspNet.Mvc.ModelBinding;
@@ -13,16 +15,22 @@ namespace Microsoft.AspNet.Mvc.Formatters
 {
     public class JsonInputFormatter : InputFormatter
     {
-        private JsonSerializerSettings _serializerSettings;
+        private readonly IArrayPool<char> _charPool;
-        private ILogger _logger;
+        private readonly ILogger _logger;
 
+        private JsonSerializerSettings _serializerSettings;
 
         public JsonInputFormatter(ILogger logger)
-            : this(logger, SerializerSettingsProvider.CreateSerializerSettings())
+            : this(logger, SerializerSettingsProvider.CreateSerializerSettings(), ArrayPool<char>.Shared)
         {
         }
 
         public JsonInputFormatter(ILogger logger, JsonSerializerSettings serializerSettings)
+            : this(logger, serializerSettings, ArrayPool<char>.Shared)
+        {
+        }
+
+        public JsonInputFormatter(ILogger logger, JsonSerializerSettings serializerSettings, ArrayPool<char> charPool)
         {
             if (serializerSettings == null)
             {
@@ -36,6 +44,7 @@ namespace Microsoft.AspNet.Mvc.Formatters
 
             _logger = logger;
             _serializerSettings = serializerSettings;
+            _charPool = new JsonArrayPool<char>(charPool);
 
             SupportedEncodings.Add(UTF8EncodingWithoutBOM);
             SupportedEncodings.Add(UTF16EncodingLittleEndian);
@@ -84,6 +93,7 @@ namespace Microsoft.AspNet.Mvc.Formatters
             {
                 using (var jsonReader = new JsonTextReader(streamReader))
                 {
+                    jsonReader.ArrayPool = _charPool;
                     jsonReader.CloseInput = false;
 
                     var successful = true;

src/Microsoft.AspNet.Mvc.Formatters.Json/JsonOutputFormatter.cs

@@ -2,9 +2,11 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
+using System.Buffers;
 using System.IO;
 using System.Text;
 using System.Threading.Tasks;
+using Microsoft.AspNet.Mvc.Formatters.Json.Internal;
 using Microsoft.AspNet.Mvc.Internal;
 using Newtonsoft.Json;
 
@@ -15,6 +17,8 @@ namespace Microsoft.AspNet.Mvc.Formatters
     /// </summary>
     public class JsonOutputFormatter : OutputFormatter
     {
+        private readonly IArrayPool<char> _charPool;
+
         private JsonSerializerSettings _serializerSettings;
 
         // Perf: JsonSerializers are relatively expensive to create, and are thread safe. We cache
@@ -22,18 +26,29 @@ namespace Microsoft.AspNet.Mvc.Formatters
         private JsonSerializer _serializer;
 
         public JsonOutputFormatter()
-            : this(SerializerSettingsProvider.CreateSerializerSettings())
+            : this(SerializerSettingsProvider.CreateSerializerSettings(), ArrayPool<char>.Shared)
         {
         }
 
         public JsonOutputFormatter(JsonSerializerSettings serializerSettings)
+            : this(serializerSettings, ArrayPool<char>.Shared)
+        {
+        }
+
+        public JsonOutputFormatter(JsonSerializerSettings serializerSettings, ArrayPool<char> charPool)
         {
             if (serializerSettings == null)
             {
                 throw new ArgumentNullException(nameof(serializerSettings));
             }
 
+            if (charPool == null)
+            {
+                throw new ArgumentNullException(nameof(charPool));
+            }
+
             _serializerSettings = serializerSettings;
+            _charPool = new JsonArrayPool<char>(charPool);
 
             SupportedEncodings.Add(Encoding.UTF8);
             SupportedEncodings.Add(Encoding.Unicode);
@@ -94,8 +109,11 @@ namespace Microsoft.AspNet.Mvc.Formatters
                 throw new ArgumentNullException(nameof(writer));
             }
 
-            var jsonWriter = new JsonTextWriter(writer);
+            var jsonWriter = new JsonTextWriter(writer)
-            jsonWriter.CloseOutput = false;
+            {
+                ArrayPool = _charPool,
+                CloseOutput = false,
+            };
 
             return jsonWriter;
         }

src/Microsoft.AspNet.Mvc.Formatters.Json/JsonPatchInputFormatter.cs

@@ -2,6 +2,7 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
+using System.Buffers;
 using System.Reflection;
 using System.Threading.Tasks;
 using Microsoft.AspNet.JsonPatch;
@@ -14,12 +15,15 @@ namespace Microsoft.AspNet.Mvc.Formatters
     public class JsonPatchInputFormatter : JsonInputFormatter
     {
         public JsonPatchInputFormatter(ILogger logger)
-            : this(logger, SerializerSettingsProvider.CreateSerializerSettings())
+            : this(logger, SerializerSettingsProvider.CreateSerializerSettings(), ArrayPool<char>.Shared)
         {
         }
 
-        public JsonPatchInputFormatter(ILogger logger, JsonSerializerSettings serializerSettings)
+        public JsonPatchInputFormatter(
-            : base(logger, serializerSettings)
+            ILogger logger,
+            JsonSerializerSettings serializerSettings,
+            ArrayPool<char> charPool)
+            : base(logger, serializerSettings, charPool)
         {
             // Clear all values and only include json-patch+json value.
             SupportedMediaTypes.Clear();

src/Microsoft.AspNet.Mvc.Formatters.Json/project.json

@@ -16,7 +16,7 @@
       "version": "1.0.0-*",
       "type": "build"
     },
-    "Newtonsoft.Json": "6.0.6"
+    "Newtonsoft.Json": "8.0.1"
   },
   "frameworks": {
     "net451": {},

src/Microsoft.AspNet.Mvc.ViewFeatures/DependencyInjection/MvcViewFeaturesMvcCoreBuilderExtensions.cs

@@ -112,7 +112,8 @@ namespace Microsoft.Extensions.DependencyInjection
             services.TryAdd(ServiceDescriptor.Singleton<JsonOutputFormatter>(serviceProvider =>
             {
                 var options = serviceProvider.GetRequiredService<IOptions<MvcJsonOptions>>().Value;
-                return new JsonOutputFormatter(options.SerializerSettings);
+                var charPool = serviceProvider.GetRequiredService<ArrayPool<char>>();
+                return new JsonOutputFormatter(options.SerializerSettings, charPool);
             }));
 
             //

test/Microsoft.AspNet.Mvc.IntegrationTests/TestMvcOptions.cs

@@ -1,6 +1,7 @@
 // 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.Buffers;
 using Microsoft.AspNet.Mvc.DataAnnotations;
 using Microsoft.AspNet.Mvc.DataAnnotations.Internal;
 using Microsoft.AspNet.Mvc.Formatters.Json.Internal;
@@ -30,7 +31,7 @@ namespace Microsoft.AspNet.Mvc.IntegrationTests
             var loggerFactory = new LoggerFactory();
             var serializerSettings = SerializerSettingsProvider.CreateSerializerSettings();
 
-            MvcJsonMvcOptionsSetup.ConfigureMvc(Value, serializerSettings, loggerFactory);
+            MvcJsonMvcOptionsSetup.ConfigureMvc(Value, serializerSettings, loggerFactory, ArrayPool<char>.Shared);
         }
 
         public MvcOptions Value { get; }