Move package initialization off the UI thread entirely #81756
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This removes the eager creation on the UI thread. To maintain compatibility with F# that accesses this on the UI thread, we'll fetch it on-demand in that case.
We had some code scheduling to the UI thread to wait for the UI context to be complete, but that's no longer necessary. Since we also had multiple derived types all setting this up, but all of them had the pattern in one way or another, this also just unifies the pattern to just one case.
This trick means we don't have to switch to the UI thread to call LoadPackage, but can stay on the background thread the whole time.
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| get | ||
| { | ||
| Assumes.Present(_componentModel_doNotAccessDirectly); | ||
| return _componentModel_doNotAccessDirectly; | ||
| if (field is null) | ||
| { | ||
| // We should have been initialized asynchronously, but somebody is asking earlier than we expected, so fetch it synchronously. | ||
| var componentModel = (IComponentModel?)GetService(typeof(SComponentModel)); | ||
| Assumes.Present(componentModel); | ||
| field = componentModel; | ||
| return field; | ||
| } | ||
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| return field; | ||
| } |
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can this just be:
get => field ??= (IComponentModel?)GetService(typeof(SComponentModel)) ?? throw etc;
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If we weren't using Assumes.Present, yes....hmmm....
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That's why I have the throw :-)
| base.RegisterInitializeAsyncWork(packageInitializationTasks); | ||
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| packageInitializationTasks.AddTask(isMainThreadTask: true, task: PackageInitializationMainThreadAsync); | ||
| packageInitializationTasks.AddTask(isMainThreadTask: false, task: PackageInitializationBackgroundThreadAsync); |
CyrusNajmabadi
approved these changes
Dec 18, 2025
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This PR cleans up the final offenders so our package initialization for the C# package and the shared RoslynPackage do not transition to the UI thread anywhere. There are still UI thread transitions in the OnAfterPackageLoad, where we register event handlers for commands and object browser interfaces. VB is also still marked as not supporting background load to a COM marshalling issue to work around some legacy code.
At this point this somewhat moots the PackageLoadTasks infrastructure, but a follow-up will be made to this PR to remove that since that'll require some coordination and testing further.