Memory leak when marshalling StringWriter between AppDomains.

src/RazorEngine.sln

@@ -1,7 +1,7 @@
 
 Microsoft Visual Studio Solution File, Format Version 12.00
 # Visual Studio 15
-VisualStudioVersion = 15.0.26621.2
+VisualStudioVersion = 15.0.26730.15
 MinimumVisualStudioVersion = 10.0.40219.1
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "RazorEngine.Core", "source\RazorEngine.Core\RazorEngine.Core.csproj", "{D268F86D-2DAB-4329-A75F-3BCF6D5BCDC4}"
 EndProject
@@ -98,82 +98,116 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "TestHelper", "test\TestHelp
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "TestRunnerHelper", "test\TestRunnerHelper\TestRunnerHelper.csproj", "{6B0E2ECB-01EE-482B-951C-9E0F0D80F030}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "TestMemory", "test\TestMemory\TestMemory.csproj", "{7E82E3B3-6223-4727-8099-CF4F31D38F10}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		Debug|Any CPU = Debug|Any CPU
 		Debug|Net40 = Debug|Net40
 		Debug|Net45 = Debug|Net45
 		Debug|Razor4 = Debug|Razor4
+		Release|Any CPU = Release|Any CPU
 		Release|Net40 = Release|Net40
 		Release|Net45 = Release|Net45
 		Release|Razor4 = Release|Razor4
 	EndGlobalSection
 	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		{D268F86D-2DAB-4329-A75F-3BCF6D5BCDC4}.Debug|Any CPU.ActiveCfg = Debug|Razor4
 		{D268F86D-2DAB-4329-A75F-3BCF6D5BCDC4}.Debug|Net40.ActiveCfg = Debug|Net40
 		{D268F86D-2DAB-4329-A75F-3BCF6D5BCDC4}.Debug|Net40.Build.0 = Debug|Net40
 		{D268F86D-2DAB-4329-A75F-3BCF6D5BCDC4}.Debug|Net45.ActiveCfg = Debug|Net45
 		{D268F86D-2DAB-4329-A75F-3BCF6D5BCDC4}.Debug|Net45.Build.0 = Debug|Net45
 		{D268F86D-2DAB-4329-A75F-3BCF6D5BCDC4}.Debug|Razor4.ActiveCfg = Debug|Razor4
 		{D268F86D-2DAB-4329-A75F-3BCF6D5BCDC4}.Debug|Razor4.Build.0 = Debug|Razor4
+		{D268F86D-2DAB-4329-A75F-3BCF6D5BCDC4}.Release|Any CPU.ActiveCfg = Release|Razor4
 		{D268F86D-2DAB-4329-A75F-3BCF6D5BCDC4}.Release|Net40.ActiveCfg = Release|Net40
 		{D268F86D-2DAB-4329-A75F-3BCF6D5BCDC4}.Release|Net40.Build.0 = Release|Net40
 		{D268F86D-2DAB-4329-A75F-3BCF6D5BCDC4}.Release|Net45.ActiveCfg = Release|Net45
 		{D268F86D-2DAB-4329-A75F-3BCF6D5BCDC4}.Release|Net45.Build.0 = Release|Net45
 		{D268F86D-2DAB-4329-A75F-3BCF6D5BCDC4}.Release|Razor4.ActiveCfg = Release|Razor4
 		{D268F86D-2DAB-4329-A75F-3BCF6D5BCDC4}.Release|Razor4.Build.0 = Release|Razor4
+		{F4F5AB5F-BF81-4C0C-8F2E-68AB02160C4E}.Debug|Any CPU.ActiveCfg = Debug|Razor4
 		{F4F5AB5F-BF81-4C0C-8F2E-68AB02160C4E}.Debug|Net40.ActiveCfg = Debug|Net40
 		{F4F5AB5F-BF81-4C0C-8F2E-68AB02160C4E}.Debug|Net40.Build.0 = Debug|Net40
 		{F4F5AB5F-BF81-4C0C-8F2E-68AB02160C4E}.Debug|Net45.ActiveCfg = Debug|Net45
 		{F4F5AB5F-BF81-4C0C-8F2E-68AB02160C4E}.Debug|Net45.Build.0 = Debug|Net45
 		{F4F5AB5F-BF81-4C0C-8F2E-68AB02160C4E}.Debug|Razor4.ActiveCfg = Debug|Razor4
 		{F4F5AB5F-BF81-4C0C-8F2E-68AB02160C4E}.Debug|Razor4.Build.0 = Debug|Razor4
+		{F4F5AB5F-BF81-4C0C-8F2E-68AB02160C4E}.Release|Any CPU.ActiveCfg = Release|Razor4
 		{F4F5AB5F-BF81-4C0C-8F2E-68AB02160C4E}.Release|Net40.ActiveCfg = Release|Net40
 		{F4F5AB5F-BF81-4C0C-8F2E-68AB02160C4E}.Release|Net40.Build.0 = Release|Net40
 		{F4F5AB5F-BF81-4C0C-8F2E-68AB02160C4E}.Release|Net45.ActiveCfg = Release|Net45
 		{F4F5AB5F-BF81-4C0C-8F2E-68AB02160C4E}.Release|Net45.Build.0 = Release|Net45
 		{F4F5AB5F-BF81-4C0C-8F2E-68AB02160C4E}.Release|Razor4.ActiveCfg = Release|Razor4
 		{F4F5AB5F-BF81-4C0C-8F2E-68AB02160C4E}.Release|Razor4.Build.0 = Release|Razor4
+		{878A8554-ACF1-4A0B-9BFC-6BD5FC5048C4}.Debug|Any CPU.ActiveCfg = Debug|Net45
 		{878A8554-ACF1-4A0B-9BFC-6BD5FC5048C4}.Debug|Net40.ActiveCfg = Debug|Net45
 		{878A8554-ACF1-4A0B-9BFC-6BD5FC5048C4}.Debug|Net45.ActiveCfg = Debug|Net45
 		{878A8554-ACF1-4A0B-9BFC-6BD5FC5048C4}.Debug|Net45.Build.0 = Debug|Net45
 		{878A8554-ACF1-4A0B-9BFC-6BD5FC5048C4}.Debug|Razor4.ActiveCfg = Debug|Net45
+		{878A8554-ACF1-4A0B-9BFC-6BD5FC5048C4}.Release|Any CPU.ActiveCfg = Release|Net45
 		{878A8554-ACF1-4A0B-9BFC-6BD5FC5048C4}.Release|Net40.ActiveCfg = Release|Net45
 		{878A8554-ACF1-4A0B-9BFC-6BD5FC5048C4}.Release|Net45.ActiveCfg = Release|Net45
 		{878A8554-ACF1-4A0B-9BFC-6BD5FC5048C4}.Release|Net45.Build.0 = Release|Net45
 		{878A8554-ACF1-4A0B-9BFC-6BD5FC5048C4}.Release|Razor4.ActiveCfg = Release|Net45
+		{BC7891A1-8459-4A69-A37C-F40824E28C70}.Debug|Any CPU.ActiveCfg = Debug|Net45
 		{BC7891A1-8459-4A69-A37C-F40824E28C70}.Debug|Net40.ActiveCfg = Debug|Net45
 		{BC7891A1-8459-4A69-A37C-F40824E28C70}.Debug|Net45.ActiveCfg = Debug|Net45
 		{BC7891A1-8459-4A69-A37C-F40824E28C70}.Debug|Net45.Build.0 = Debug|Net45
 		{BC7891A1-8459-4A69-A37C-F40824E28C70}.Debug|Razor4.ActiveCfg = Debug|Net45
+		{BC7891A1-8459-4A69-A37C-F40824E28C70}.Release|Any CPU.ActiveCfg = Release|Net45
 		{BC7891A1-8459-4A69-A37C-F40824E28C70}.Release|Net40.ActiveCfg = Release|Net45
 		{BC7891A1-8459-4A69-A37C-F40824E28C70}.Release|Net45.ActiveCfg = Release|Net45
 		{BC7891A1-8459-4A69-A37C-F40824E28C70}.Release|Net45.Build.0 = Release|Net45
 		{BC7891A1-8459-4A69-A37C-F40824E28C70}.Release|Razor4.ActiveCfg = Release|Net45
+		{7CB02F9F-7E88-448B-A25B-7985058296C5}.Debug|Any CPU.ActiveCfg = Debug|Razor4
 		{7CB02F9F-7E88-448B-A25B-7985058296C5}.Debug|Net40.ActiveCfg = Debug|Net40
 		{7CB02F9F-7E88-448B-A25B-7985058296C5}.Debug|Net45.ActiveCfg = Debug|Net45
 		{7CB02F9F-7E88-448B-A25B-7985058296C5}.Debug|Net45.Build.0 = Debug|Net45
 		{7CB02F9F-7E88-448B-A25B-7985058296C5}.Debug|Razor4.ActiveCfg = Debug|Razor4
 		{7CB02F9F-7E88-448B-A25B-7985058296C5}.Debug|Razor4.Build.0 = Debug|Razor4
+		{7CB02F9F-7E88-448B-A25B-7985058296C5}.Release|Any CPU.ActiveCfg = Release|Razor4
 		{7CB02F9F-7E88-448B-A25B-7985058296C5}.Release|Net40.ActiveCfg = Release|Net40
 		{7CB02F9F-7E88-448B-A25B-7985058296C5}.Release|Net45.ActiveCfg = Release|Net45
 		{7CB02F9F-7E88-448B-A25B-7985058296C5}.Release|Net45.Build.0 = Release|Net45
 		{7CB02F9F-7E88-448B-A25B-7985058296C5}.Release|Razor4.ActiveCfg = Release|Razor4
 		{7CB02F9F-7E88-448B-A25B-7985058296C5}.Release|Razor4.Build.0 = Release|Razor4
+		{7899C0AE-844D-4A34-B3BC-96819C73EA68}.Debug|Any CPU.ActiveCfg = Debug|Net45
 		{7899C0AE-844D-4A34-B3BC-96819C73EA68}.Debug|Net40.ActiveCfg = Debug|Net45
 		{7899C0AE-844D-4A34-B3BC-96819C73EA68}.Debug|Net45.ActiveCfg = Debug|Net45
 		{7899C0AE-844D-4A34-B3BC-96819C73EA68}.Debug|Net45.Build.0 = Debug|Net45
 		{7899C0AE-844D-4A34-B3BC-96819C73EA68}.Debug|Razor4.ActiveCfg = Debug|Net45
+		{7899C0AE-844D-4A34-B3BC-96819C73EA68}.Release|Any CPU.ActiveCfg = Release|Net45
 		{7899C0AE-844D-4A34-B3BC-96819C73EA68}.Release|Net40.ActiveCfg = Release|Net45
 		{7899C0AE-844D-4A34-B3BC-96819C73EA68}.Release|Net45.ActiveCfg = Release|Net45
 		{7899C0AE-844D-4A34-B3BC-96819C73EA68}.Release|Net45.Build.0 = Release|Net45
 		{7899C0AE-844D-4A34-B3BC-96819C73EA68}.Release|Razor4.ActiveCfg = Release|Net45
+		{6B0E2ECB-01EE-482B-951C-9E0F0D80F030}.Debug|Any CPU.ActiveCfg = Debug|Net45
 		{6B0E2ECB-01EE-482B-951C-9E0F0D80F030}.Debug|Net40.ActiveCfg = Debug|Net45
 		{6B0E2ECB-01EE-482B-951C-9E0F0D80F030}.Debug|Net45.ActiveCfg = Debug|Net45
 		{6B0E2ECB-01EE-482B-951C-9E0F0D80F030}.Debug|Net45.Build.0 = Debug|Net45
 		{6B0E2ECB-01EE-482B-951C-9E0F0D80F030}.Debug|Razor4.ActiveCfg = Debug|Net45
+		{6B0E2ECB-01EE-482B-951C-9E0F0D80F030}.Release|Any CPU.ActiveCfg = Release|Net45
 		{6B0E2ECB-01EE-482B-951C-9E0F0D80F030}.Release|Net40.ActiveCfg = Release|Net45
 		{6B0E2ECB-01EE-482B-951C-9E0F0D80F030}.Release|Net45.ActiveCfg = Release|Net45
 		{6B0E2ECB-01EE-482B-951C-9E0F0D80F030}.Release|Net45.Build.0 = Release|Net45
 		{6B0E2ECB-01EE-482B-951C-9E0F0D80F030}.Release|Razor4.ActiveCfg = Release|Net45
+		{7E82E3B3-6223-4727-8099-CF4F31D38F10}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{7E82E3B3-6223-4727-8099-CF4F31D38F10}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{7E82E3B3-6223-4727-8099-CF4F31D38F10}.Debug|Net40.ActiveCfg = Debug|Any CPU
+		{7E82E3B3-6223-4727-8099-CF4F31D38F10}.Debug|Net40.Build.0 = Debug|Any CPU
+		{7E82E3B3-6223-4727-8099-CF4F31D38F10}.Debug|Net45.ActiveCfg = Debug|Any CPU
+		{7E82E3B3-6223-4727-8099-CF4F31D38F10}.Debug|Net45.Build.0 = Debug|Any CPU
+		{7E82E3B3-6223-4727-8099-CF4F31D38F10}.Debug|Razor4.ActiveCfg = Debug|Any CPU
+		{7E82E3B3-6223-4727-8099-CF4F31D38F10}.Debug|Razor4.Build.0 = Debug|Any CPU
+		{7E82E3B3-6223-4727-8099-CF4F31D38F10}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{7E82E3B3-6223-4727-8099-CF4F31D38F10}.Release|Any CPU.Build.0 = Release|Any CPU
+		{7E82E3B3-6223-4727-8099-CF4F31D38F10}.Release|Net40.ActiveCfg = Release|Any CPU
+		{7E82E3B3-6223-4727-8099-CF4F31D38F10}.Release|Net40.Build.0 = Release|Any CPU
+		{7E82E3B3-6223-4727-8099-CF4F31D38F10}.Release|Net45.ActiveCfg = Release|Any CPU
+		{7E82E3B3-6223-4727-8099-CF4F31D38F10}.Release|Net45.Build.0 = Release|Any CPU
+		{7E82E3B3-6223-4727-8099-CF4F31D38F10}.Release|Razor4.ActiveCfg = Release|Any CPU
+		{7E82E3B3-6223-4727-8099-CF4F31D38F10}.Release|Razor4.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
@@ -192,9 +226,10 @@ Global
 		{7CB02F9F-7E88-448B-A25B-7985058296C5} = {AE7E811A-2B9F-45BC-9752-0FB4D1DEE12D}
 		{7899C0AE-844D-4A34-B3BC-96819C73EA68} = {AE7E811A-2B9F-45BC-9752-0FB4D1DEE12D}
 		{6B0E2ECB-01EE-482B-951C-9E0F0D80F030} = {AE7E811A-2B9F-45BC-9752-0FB4D1DEE12D}
+		{7E82E3B3-6223-4727-8099-CF4F31D38F10} = {AE7E811A-2B9F-45BC-9752-0FB4D1DEE12D}
 	EndGlobalSection
 	GlobalSection(ExtensibilityGlobals) = postSolution
-		SolutionGuid = {87BAAA5F-5CFE-4284-91D8-C3C5F4083599}
 		EnterpriseLibraryConfigurationToolBinariesPath = packages\Unity.2.1.505.0\lib\NET35
+		SolutionGuid = {87BAAA5F-5CFE-4284-91D8-C3C5F4083599}
 	EndGlobalSection
 EndGlobal

src/source/RazorEngine.Core/Templating/RazorEngineServiceExtensions.cs

@@ -217,11 +217,15 @@ public static void RunCompile(this IRazorEngineService service, string templateS
         /// <returns></returns>
         private static string WithWriter(Action<TextWriter> withWriter)
         {
-            using (var writer = new System.IO.StringWriter())
-            {
+            // There seems to be something wrong with using a StringWriter when marshalling it to the other AppDomain. 
+            // The internal StringBuilder instance inside StringWriter will not get GC:ed until several minutes later, 
+            // resulting in OutOfMemoryException on high load. If we use a StreamWriter instead, the problem will go away.
+            var ms = new MemoryStream();
+
+            using (var writer = new StreamWriter(ms))
                 withWriter(writer);
-                return writer.ToString();
-            }
+
+            return System.Text.Encoding.UTF8.GetString(ms.ToArray());
         }
 
         /// <summary>

src/test/TestMemory/App.config

@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="utf-8"?>
+<configuration>
+    <startup> 
+        <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.7"/>
+    </startup>
+</configuration>

src/test/TestMemory/Program.cs

@@ -0,0 +1,37 @@
+using System;
+using System.Linq;
+using RazorEngine.Templating;
+
+namespace TestMemory
+{
+  [Serializable]
+  public class TemplateModel
+  {
+    public string Name { get; set; }
+  }
+
+  class Program
+  {
+    static void Main(string[] args)
+    {
+      using (var service = IsolatedRazorEngineService.Create())
+      {
+        service.AddTemplate("TestTemplate",
+          "Hello @Model.Name " + new String(Enumerable.Repeat('A', 100000).ToArray()));
+        service.Compile("TestTemplate", typeof(TemplateModel));
+
+        int counter = 0;
+
+        while (!Console.KeyAvailable)
+        {
+          var result = service.Run("TestTemplate", typeof(TemplateModel), new TemplateModel {Name = "World"});
+          Console.WriteLine("Run: {0}. Result: {1}", ++counter, result.Substring(0, 20));
+        }
+      }
+
+      Console.ReadKey();
+      Console.WriteLine("Key pressed. Press a key again to quit");
+      Console.ReadKey();
+    }
+  }
+}

src/test/TestMemory/Properties/AssemblyInfo.cs

@@ -0,0 +1,36 @@
+using System.Reflection;
+using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
+
+// General Information about an assembly is controlled through the following
+// set of attributes. Change these attribute values to modify the information
+// associated with an assembly.
+[assembly: AssemblyTitle("TestMemory")]
+[assembly: AssemblyDescription("")]
+[assembly: AssemblyConfiguration("")]
+[assembly: AssemblyCompany("")]
+[assembly: AssemblyProduct("TestMemory")]
+[assembly: AssemblyCopyright("Copyright ©  2017")]
+[assembly: AssemblyTrademark("")]
+[assembly: AssemblyCulture("")]
+
+// Setting ComVisible to false makes the types in this assembly not visible
+// to COM components.  If you need to access a type in this assembly from
+// COM, set the ComVisible attribute to true on that type.
+[assembly: ComVisible(false)]
+
+// The following GUID is for the ID of the typelib if this project is exposed to COM
+[assembly: Guid("7e82e3b3-6223-4727-8099-cf4f31d38f10")]
+
+// Version information for an assembly consists of the following four values:
+//
+//      Major Version
+//      Minor Version
+//      Build Number
+//      Revision
+//
+// You can specify all the values or you can default the Build and Revision Numbers
+// by using the '*' as shown below:
+// [assembly: AssemblyVersion("1.0.*")]
+[assembly: AssemblyVersion("1.0.0.0")]
+[assembly: AssemblyFileVersion("1.0.0.0")]

src/test/TestMemory/TestMemory.csproj

@@ -0,0 +1,59 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Project ToolsVersion="15.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <Import Project="$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props" Condition="Exists('$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props')" />
+  <PropertyGroup>
+    <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
+    <Platform Condition=" '$(Platform)' == '' ">AnyCPU</Platform>
+    <ProjectGuid>{7E82E3B3-6223-4727-8099-CF4F31D38F10}</ProjectGuid>
+    <OutputType>Exe</OutputType>
+    <RootNamespace>TestMemory</RootNamespace>
+    <AssemblyName>TestMemory</AssemblyName>
+    <TargetFrameworkVersion>v4.7</TargetFrameworkVersion>
+    <FileAlignment>512</FileAlignment>
+    <AutoGenerateBindingRedirects>true</AutoGenerateBindingRedirects>
+    <TargetFrameworkProfile />
+  </PropertyGroup>
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
+    <PlatformTarget>AnyCPU</PlatformTarget>
+    <DebugSymbols>true</DebugSymbols>
+    <DebugType>full</DebugType>
+    <Optimize>false</Optimize>
+    <OutputPath>bin\Debug\</OutputPath>
+    <DefineConstants>DEBUG;TRACE</DefineConstants>
+    <ErrorReport>prompt</ErrorReport>
+    <WarningLevel>4</WarningLevel>
+  </PropertyGroup>
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
+    <PlatformTarget>AnyCPU</PlatformTarget>
+    <DebugType>pdbonly</DebugType>
+    <Optimize>true</Optimize>
+    <OutputPath>bin\Release\</OutputPath>
+    <DefineConstants>TRACE</DefineConstants>
+    <ErrorReport>prompt</ErrorReport>
+    <WarningLevel>4</WarningLevel>
+  </PropertyGroup>
+  <ItemGroup>
+    <Reference Include="System" />
+    <Reference Include="System.Core" />
+    <Reference Include="System.Xml.Linq" />
+    <Reference Include="System.Data.DataSetExtensions" />
+    <Reference Include="Microsoft.CSharp" />
+    <Reference Include="System.Data" />
+    <Reference Include="System.Net.Http" />
+    <Reference Include="System.Xml" />
+  </ItemGroup>
+  <ItemGroup>
+    <Compile Include="Program.cs" />
+    <Compile Include="Properties\AssemblyInfo.cs" />
+  </ItemGroup>
+  <ItemGroup>
+    <None Include="App.config" />
+  </ItemGroup>
+  <ItemGroup>
+    <ProjectReference Include="..\..\source\RazorEngine.Core\RazorEngine.Core.csproj">
+      <Project>{D268F86D-2DAB-4329-A75F-3BCF6D5BCDC4}</Project>
+      <Name>RazorEngine.Core</Name>
+    </ProjectReference>
+  </ItemGroup>
+  <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
+</Project>