Remove GetService(...) calls from VS MEF importing constructors #10168
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The `VisualStudioEditorDocumentManager` listens for running document table events and was retrieving the `IVsRunningDocumentTable` in its constructor. Because this is an `[ImportingConstructor]` it will almost certain be called on the thread pool and will implicitly marshal to the UI thread to perform a QI as part of retrieving the service. This can cause a hang if the UI thread is tied up with other work, such as when a solution is loaded. This change avoids retrieving the running doc table service until its needed and we are already running on the UI thread.
`VisualStudioFileChangeTrackerFactory` retrieves an `IVsAsyncFileChangeEx` service in its constructor. Because this is an `[ImportingConstructor]` it will likely be called on the thread pool and implicitly marshal to the UI thread to perform a QI as part of retrieving the service. This can cause a hang if the UI thread is tied up with other work, such as when a solution is loaded. This change avoids retrieving `IVsAsyncFileChangeEx` until its needed. This does block on retrieving the service. However, avoiding that will require a more substantial change that I'll follow up with on `main`.
ryzngard
approved these changes
Mar 26, 2024
...Microsoft.VisualStudio.LanguageServices.Razor/Documents/VisualStudioEditorDocumentManager.cs
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...rosoft.VisualStudio.LanguageServices.Razor/Documents/VisualStudioFileChangeTrackerFactory.cs
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phil-allen-msft
approved these changes
Mar 26, 2024
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We observed a hang during solution load because
VisualStudioEditorDocumentManagerretrieves theIVsRunningDocumentTableservice in its constructor. When this constructor is called on a background thread, it results in an implicit marshal to the UI thread in order to retrieve the service and QI for its COM interface. This change fixes that issue delaying the request forIVsRunningDocumentTableuntil it is needed and running on the UI thread.In addition,
VisualStudioFileChangeTrackerFactoryhad a similar issue but withIVsAsyncFileChangeEx. BecauseIFileChangeTrackerFactoryis imported byVisualStudioEditorDocumentManager, I've fixed this service as well.