[windows] fix VisualDiagnosticsOverlay keeping Page's alive#23489
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jonathanpeppers merged 2 commits intoJul 10, 2024
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Fixes: dotnet#23034 Context: https://github.com/user-attachments/files/15817814/MauiApp1.zip In the above sample app, you can observe a memory leak on Windows by doing: Application.Current.MainPage = new Page1(); // This page lives forever Application.Current.MainPage = new Page2(); Reviewing memory snapshots, it appears that the `VisualDiagnosticsOverlay` class is keeping the `Page1` instance alive: MauiApp1.Page1 -> Microsoft.Maui.Platform.ContentPanel -> Microsoft.Maui.Controls.VisualDiagnostics.VisualDiagnosticsOverlay -> Microsoft.Maui.Controls.Window In this case, the `Window` holds a reference to the `VisualDiagnosticsOverlay`, and the `Window` is still open. `VisualDiagnosticsOverlay`'s base class is `WindowOverlay`, which has a `_platformElement` field holding the `ContentPanel` which holds the `Page1` instance. In this case, `_platformElement` is only used for unsubscribing events, so it feels like we can just change it to a `WeakReference` to solve the issue. I was able to write a test for this scenario as well.
jonathanpeppers
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perf/memory-leak 💦
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The iOS/Catalyst tests have a failure: |
jonathanpeppers
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Jul 9, 2024
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| [Fact("VisualDiagnosticsOverlay Does Not Leak" | ||
| #if IOS || MACCATALYST | ||
| , Skip = "Fails with 'MauiContext should have been set on parent.'" | ||
| #endif | ||
| )] |
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I did not figure out how to get this test to work on iOS/Catalyst. It seems like it wants the Window's Handler to be created for it to work.
In either case, I think there is only a problem on Windows here.
Redth
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Jul 10, 2024
samhouts
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Fixes: #23034
Context: https://github.com/user-attachments/files/15817814/MauiApp1.zip
In the above sample app, you can observe a memory leak on Windows by doing:
Reviewing memory snapshots, it appears that the
VisualDiagnosticsOverlayclass is keeping thePage1instance alive:In this case, the
Windowholds a reference to theVisualDiagnosticsOverlay, and theWindowis still open.VisualDiagnosticsOverlay's base class isWindowOverlay, which has a_platformElementfield holding theContentPanelwhich holds thePage1instance.In this case,
_platformElementis only used for unsubscribing events, so it feels like we can just change it to aWeakReferenceto solve the issue.I was able to write a test for this scenario as well.