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Try and use AssemblyLoadContext to load and unload assemblies

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This still doesn't work, since the old assembly never gets freed allowing it to be unloaded, my best guess is that there's some references to the types within in the old assembly somewhere which doesn't get cleared.
This commit is contained in:
Mole
2020-09-04 10:38:37 +02:00
parent 63c25b8695
commit 1000e19a20
3 changed files with 68 additions and 18 deletions
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58
src/Umbraco.ModelsBuilder.Embedded/PureLiveModelFactory.cs
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@@ -18,13 +18,11 @@ using Umbraco.Core.Models.PublishedContent;
using Umbraco.ModelsBuilder.Embedded.Building;
using File = System.IO.File;
using Umbraco.Core.Composing;
using System.Runtime.Loader;
namespace Umbraco.ModelsBuilder.Embedded
{
internal class PureLiveModelFactory : ILivePublishedModelFactory, IRegisteredObject
{
private Assembly _modelsAssembly;
private Infos _infos = new Infos { ModelInfos = null, ModelTypeMap = new Dictionary<string, Type>() };
private readonly ReaderWriterLockSlim _locker = new ReaderWriterLockSlim();
private volatile bool _hasModels; // volatile 'cos reading outside lock
@@ -34,6 +32,8 @@ namespace Umbraco.ModelsBuilder.Embedded
private int _ver, _skipver;
private readonly int _debugLevel;
private RoslynCompiler _roslynCompiler;
private UmbracoAssemblyLoadContext _currentAssemblyLoadContext;
private WeakReference _oldAssemblyLoadContext;
private readonly Lazy<UmbracoServices> _umbracoServices; // fixme: this is because of circular refs :(
private UmbracoServices UmbracoServices => _umbracoServices.Value;
@@ -247,9 +247,6 @@ namespace Umbraco.ModelsBuilder.Embedded
// this is for U4-8043 which is an obvious issue but I cannot replicate
//_modelsAssembly = _modelsAssembly ?? assembly;
// the one below is the normal one
_modelsAssembly = assembly;
var types = assembly.ExportedTypes.Where(x => x.Inherits<PublishedContentModel>() || x.Inherits<PublishedElementModel>());
_infos = RegisterModels(types);
_errors.Clear();
@@ -264,7 +261,6 @@ namespace Umbraco.ModelsBuilder.Embedded
}
finally
{
_modelsAssembly = null;
_infos = new Infos { ModelInfos = null, ModelTypeMap = new Dictionary<string, Type>() };
}
}
@@ -286,6 +282,25 @@ namespace Umbraco.ModelsBuilder.Embedded
}
}
private Assembly ReloadAssembly(string pathToAssembly)
{
// No AssemblyLoadContext has been loaded yet
// Just load assembly and we're done
if(_currentAssemblyLoadContext is null)
{
_currentAssemblyLoadContext = new UmbracoAssemblyLoadContext();
return _currentAssemblyLoadContext.LoadFromAssemblyPath(pathToAssembly);
}
// We must create a weak reference to the old assemblycontext in order to make sure later that it's no longer alive
_oldAssemblyLoadContext = new WeakReference(_currentAssemblyLoadContext, trackResurrection: true);
_currentAssemblyLoadContext.Unload();
// We must create a new assembly load context
// as long as theres a reference to the assembly load context we can't delete the assembly it loaded
_currentAssemblyLoadContext = new UmbracoAssemblyLoadContext();
return _currentAssemblyLoadContext.LoadFromAssemblyPath(pathToAssembly);
}
private Assembly GetModelsAssembly(bool forceRebuild)
{
var modelsDirectory = _config.ModelsDirectoryAbsolute(_hostingEnvironment);
@@ -340,9 +355,7 @@ namespace Umbraco.ModelsBuilder.Embedded
if (File.Exists(dllPath) && !File.Exists(dllPath + ".delete"))
{
// TODO: Figure out loading and unloading the assemblies to allow you to delete them.
AssemblyLoadContext assemblyContext = new AssemblyLoadContext("ModelsBuilder");
assembly = assemblyContext.LoadFromAssemblyPath(dllPath);
assembly = ReloadAssembly(dllPath);
var attr = assembly.GetCustomAttribute<ModelsBuilderAssemblyAttribute>();
if (attr != null && attr.PureLive && attr.SourceHash == currentHash)
@@ -382,7 +395,8 @@ namespace Umbraco.ModelsBuilder.Embedded
_ver++;
try
{
assembly = RoslynCompiler.GetCompiledAssembly(_hostingEnvironment.MapPathContentRoot(projFile), GetOutputAssemblyPath(currentHash));
var assemblyPath = RoslynCompiler.GetCompiledAssembly(_hostingEnvironment.MapPathContentRoot(projFile), GetOutputAssemblyPath(currentHash));
assembly = ReloadAssembly(assemblyPath);
File.WriteAllText(dllPathFile, assembly.Location);
TryDeleteUnusedAssemblies(dllPathFile);
}
@@ -421,7 +435,8 @@ namespace Umbraco.ModelsBuilder.Embedded
// compile and register
try
{
assembly = RoslynCompiler.GetCompiledAssembly(_hostingEnvironment.MapPathContentRoot(projFile), GetOutputAssemblyPath(currentHash));
var assemblyPath = RoslynCompiler.GetCompiledAssembly(_hostingEnvironment.MapPathContentRoot(projFile), GetOutputAssemblyPath(currentHash));
assembly = ReloadAssembly(assemblyPath);
File.WriteAllText(dllPathFile, assembly.Location);
File.WriteAllText(modelsHashFile, currentHash);
TryDeleteUnusedAssemblies(dllPathFile);
@@ -436,11 +451,24 @@ namespace Umbraco.ModelsBuilder.Embedded
return assembly;
}
private static void TryDeleteUnusedAssemblies(string dllPathFile)
private void TryDeleteUnusedAssemblies(string dllPathFile)
{
// We can't do this because the dllPathFile gets deleted when a new document type is saved
// But how do we delete the old assembly?
// It seems like ISS doesn't release it even though a new dll is genrated and loaded.
// Try and garbage collect to hopefully kill the old assembly
// This might be slow??
// I'm doing as mentioned in: https://docs.microsoft.com/en-us/dotnet/standard/assembly/unloadability
// The old assembly still doesn't get unloaded properly
// My best guess is that there's some some references to the types within the assembly somewhere
// which means that the assembly won't unload because it does so in a cooporative manner
// but I have no clue how to fix this
if (!(_oldAssemblyLoadContext is null))
{
for (int i = 0; _oldAssemblyLoadContext.IsAlive && (i < 10); i++)
{
GC.Collect();
GC.WaitForPendingFinalizers();
}
}
if (File.Exists(dllPathFile))
{
var dllPath = File.ReadAllText(dllPathFile);