Package load failure when trying to lauch Navigate To after opening a solution

[shyamnamboodiripad]

Version Used: VS 16.0 P1 build 28231.51.d16.0

Steps to Reproduce:

1. Open a solution in VS without any files open in the editor
2. Ctrl + , to launch Navigate To
3. Search for some type

Note: Problem does not repro if you already had some files from the solution open in the editor at the point where Navigate To was launched.

Expected Behavior: Should succeed

Actual Behavior: Following package load failure error -

On debugging the underlying issue appears to be that AbstractNavigateToSearchService is trying to instantiate VisualStudioExperimentationService from the background thread resulting in an InvalidOperationException from the following Contract.ThrowIfFalse() call.

Dump file: Available at \\<internalshare>\\<myfolder>\Dumps\RoslynPackageLoad

      Microsoft.CodeAnalysis.Workspaces.dll!Roslyn.Utilities.Contract.ThrowIfFalse(bool condition, string message) Line 32  C#
Microsoft.CodeAnalysis.EditorFeatures.dll!Microsoft.CodeAnalysis.Editor.Shared.Utilities.ForegroundThreadAffinitizedObject.AssertIsForeground() Line 56   C#
Microsoft.CodeAnalysis.EditorFeatures.dll!Microsoft.CodeAnalysis.Editor.Shared.Utilities.ForegroundThreadAffinitizedObject.ForegroundThreadAffinitizedObject(Microsoft.CodeAnalysis.Editor.Shared.Utilities.IThreadingContext threadingContext, bool assertIsForeground) Line 34   C#
> Microsoft.VisualStudio.LanguageServices.dll!Microsoft.VisualStudio.LanguageServices.Experimentation.VisualStudioExperimentationService.VisualStudioExperimentationService(Microsoft.CodeAnalysis.Editor.Shared.Utilities.IThreadingContext threadingContext, Microsoft.VisualStudio.Shell.SVsServiceProvider serviceProvider) Line 27   C#
              [Native to Managed Transition]      
              [Managed to Native Transition]      
Microsoft.VisualStudio.Composition.dll!Microsoft.VisualStudio.Composition.ReflectionHelpers.Instantiate(System.Reflection.MethodBase ctorOrFactoryMethod, object[] arguments) Line 595  C#
Microsoft.VisualStudio.Composition.dll!Microsoft.VisualStudio.Composition.RuntimeExportProviderFactory.RuntimeExportProvider.RuntimePartLifecycleTracker.CreateValue() Line 517 C#
Microsoft.VisualStudio.Composition.dll!Microsoft.VisualStudio.Composition.ExportProvider.PartLifecycleTracker.Create() Line 1160             C#
Microsoft.VisualStudio.Composition.dll!Microsoft.VisualStudio.Composition.ExportProvider.PartLifecycleTracker.MoveNext(Microsoft.VisualStudio.Composition.ExportProvider.PartLifecycleState nextState) Line 1255          C#
Microsoft.VisualStudio.Composition.dll!Microsoft.VisualStudio.Composition.ExportProvider.PartLifecycleTracker.MoveToState(Microsoft.VisualStudio.Composition.ExportProvider.PartLifecycleState requiredState) Line 1336   C#
Microsoft.VisualStudio.Composition.dll!Microsoft.VisualStudio.Composition.ExportProvider.PartLifecycleTracker.GetValueReadyToExpose() Line 1061             C#
Microsoft.VisualStudio.Composition.dll!Microsoft.VisualStudio.Composition.ExportProvider.CreateExport.AnonymousMethod__0() Line 461 C#
              mscorlib.dll!System.Lazy<object>.CreateValue() Line 437         C#
              mscorlib.dll!System.Lazy<object>.LazyInitValue() Line 388       C#
              mscorlib.dll!System.Lazy<object>.Value.get() Line 339             C#
Microsoft.VisualStudio.Composition.dll!Microsoft.VisualStudio.Composition.NetFxAdapters.MefV1ExportProvider.UnwrapExport.AnonymousMethod__1() Line 246 C#
System.ComponentModel.Composition.dll!System.ComponentModel.Composition.Primitives.Export.GetExportedValueCore() Line 247 C#
System.ComponentModel.Composition.dll!System.ComponentModel.Composition.Primitives.Export.Value.get() Line 207 C#
System.ComponentModel.Composition.dll!System.ComponentModel.Composition.ExportServices.GetCastedExportedValue<Microsoft.CodeAnalysis.Host.IWorkspaceService>(System.ComponentModel.Composition.Primitives.Export export) Line 135  C#
System.ComponentModel.Composition.dll!System.ComponentModel.Composition.ExportServices.CreateStronglyTypedLazyOfTM.AnonymousMethod__1() Line 88   C#
mscorlib.dll!System.Lazy<Microsoft.CodeAnalysis.Host.IWorkspaceService>.CreateValue() Line 437 C#
mscorlib.dll!System.Lazy<Microsoft.CodeAnalysis.Host.IWorkspaceService>.LazyInitValue() Line 359 C#
mscorlib.dll!System.Lazy<Microsoft.CodeAnalysis.Host.IWorkspaceService>.Value.get() Line 339 C#
Microsoft.CodeAnalysis.Workspaces.dll!Microsoft.CodeAnalysis.Host.Mef.MefWorkspaceServices.GetService<Microsoft.CodeAnalysis.Experiments.IExperimentationService>() Line 49   C#
Microsoft.CodeAnalysis.Workspaces.dll!Microsoft.CodeAnalysis.Remote.RemoteHostClientExtensions.IsOutOfProcessEnabled(Microsoft.CodeAnalysis.Workspace workspace, Microsoft.CodeAnalysis.Options.Option<bool> featureOption) Line 129              C#
Microsoft.CodeAnalysis.Workspaces.dll!Microsoft.CodeAnalysis.Remote.RemoteHostClientExtensions.TryGetRemoteHostClientAsync(Microsoft.CodeAnalysis.Workspace workspace, Microsoft.CodeAnalysis.Options.Option<bool> featureOption, System.Threading.CancellationToken cancellationToken) Line 135         C#
Microsoft.CodeAnalysis.Features.dll!Microsoft.CodeAnalysis.NavigateTo.AbstractNavigateToSearchService.TryGetRemoteHostClientAsync(Microsoft.CodeAnalysis.Project project, System.Threading.CancellationToken cancellationToken) Line 47           C#
Microsoft.CodeAnalysis.Features.dll!Microsoft.CodeAnalysis.NavigateTo.AbstractNavigateToSearchService.SearchProjectAsync(Microsoft.CodeAnalysis.Project project, System.Collections.Immutable.ImmutableArray<Microsoft.CodeAnalysis.Document> priorityDocuments, string searchPattern, System.Collections.Immutable.IImmutableSet<string> kinds, System.Threading.CancellationToken cancellationToken)        C#
Microsoft.CodeAnalysis.EditorFeatures.Wpf.dll!Microsoft.CodeAnalysis.Editor.Implementation.NavigateTo.NavigateToItemProvider.Searcher.SearchAsyncWorker(Microsoft.CodeAnalysis.Project project, System.Collections.Immutable.ImmutableArray<Microsoft.CodeAnalysis.Document> priorityDocuments) Line 189           C#
Microsoft.CodeAnalysis.EditorFeatures.Wpf.dll!Microsoft.CodeAnalysis.Editor.Implementation.NavigateTo.NavigateToItemProvider.Searcher.SearchAsync(Microsoft.CodeAnalysis.Project project, System.Collections.Immutable.ImmutableArray<Microsoft.CodeAnalysis.Document> priorityDocuments)           C#
Microsoft.CodeAnalysis.EditorFeatures.Wpf.dll!Microsoft.CodeAnalysis.Editor.Implementation.NavigateTo.NavigateToItemProvider.Searcher.SearchProjectsInPriorityOrder.AnonymousMethod__5() Line 146 C#
mscorlib.dll!System.Threading.Tasks.Task<System.Threading.Tasks.Task>.InnerInvoke() Line 680 C#
              mscorlib.dll!System.Threading.Tasks.Task.Execute() Line 2498 C#
              mscorlib.dll!System.Threading.Tasks.Task.ExecutionContextCallback(object obj) Line 2861      C#
mscorlib.dll!System.Threading.ExecutionContext.RunInternal(System.Threading.ExecutionContext executionContext, System.Threading.ContextCallback callback, object state, bool preserveSyncCtx) Line 954 C#
mscorlib.dll!System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext executionContext, System.Threading.ContextCallback callback, object state, bool preserveSyncCtx) Line 902 C#
              mscorlib.dll!System.Threading.Tasks.Task.ExecuteWithThreadLocal(ref System.Threading.Tasks.Task currentTaskSlot) Line 2827         C#
              mscorlib.dll!System.Threading.Tasks.Task.ExecuteEntry(bool bPreventDoubleExecution) Line 2756            C#
mscorlib.dll!System.Threading.Tasks.Task.System.Threading.IThreadPoolWorkItem.ExecuteWorkItem() Line 2704             C#
              mscorlib.dll!System.Threading.ThreadPoolWorkQueue.Dispatch() Line 820              C#
           mscorlib.dll!System.Threading._ThreadPoolWaitCallback.PerformWaitCallback() Line 1161             C#

[shyamnamboodiripad]

cc @sharwell @jasonmalinowski @jinujoseph

This is a regression and we should ideally address this soon since it can affect dogfooding.

[sharwell]

I see two primary ways to resolve this:

1. Use JTF in the constructor to remove the caller affinity requirement.
2. Make IsExperimentEnabled an asynchronous method that lazily initializes the function. In can return ValueTask<bool> since the majority case (after initialization) doesn't need to jump to the main thread again.

[davkean]

The fix here sharwell@9ddfbf0 is incorrect, JFT.Run shouldn't be used in MEF constructors and can lead to deadlocks and possible thread-starvation, please see: https://github.com/Microsoft/vs-threading/blob/master/doc/cookbook_vs.md#how-do-i-effectively-verify-that-my-code-is-fully-free-threaded, in particular:

It is not always necessary for code to be free-threaded. There are many cases where code must run on the main thread because it calls into other code that itself has thread-affinity or is not thread-safe. Important places to be free-threaded include:

1. Code that runs in the MEF activation code paths (e.g. importing constructors, OnImportsSatisfied callbacks, and any code called therefrom).

We just recently removed a bunch of these across the product. The pattern elsewhere is to wrap this in an AsyncLazy<T> and just switch to the UI thread on first access.

[sharwell]

@davkean The fix there is an interim solution only. A proper fix is in a follow-up PR (#30929) for preview 2.