SkiaSharp on iOS gets corrupted after opening and hiding many pages, grids and layouts

[janne-hmp]

I'm working on a game called GnollHack in .NET MAUI 9.0 Preview 6 that uses SkiaSharp 3.0 Preview 3.1 with several SKCanvasViews. However, after opening and hiding several pages or grids covering the whole page, SkiaSharp somehow gets corrupted and starts drawing just black. It may be a memory issue, runtime issue, composition engine issue, or something else.

In Xamarin iOS using SkiaSharp 2.88.8, the same pages and grids worked just fine. They also work with SkiaSharp 3.0 Preview 3.1 on Android and Windows. So this seems to be a .NET MAUI problem on iOS, perhaps something with .NET runtime on iOS or the like.

I have already posted this to SkiaSharp repository many months ago, but there have been no reaction to it, and the problem persists in .NET MAUI 9.0 Preview 6. This really prevents any serious use of SkiaSharp on iOS in .NET MAUI, and in consequence the publication of our game on iOS as well, so it is a pretty critical issue overall.

Does anybody know any settings for the project file or workarounds I could try here?

Steps to Reproduce

1. Download the test app at https://github.com/hyvanmielenpelit/iOSMauiSkiaSharpMemoryLeak
2. Press click me, which start's opening and closing the same page up to 500 times
3. The app crashes after it runs out of memory. My old iPad (11,7) crashed after 145th time.

Expected Behavior

SkiaSharp works just as in Xamarin iOS in .NET MAUI.

Actual Behavior

All SkiaSharp canvases start drawing black after a few clicks of Play Game.

Environment

iPad 11,7. iOS 17.5.1

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Build Logs

Available upon request, but everything builds just fine.

Example Project (If Possible)

https://github.com/hyvanmielenpelit/iOSMauiSkiaSharpMemoryLeak

[janne-hmp]

I just made a new example project here: https://github.com/hyvanmielenpelit/iOSMauiSkiaSharpMemoryLeak . It tries to open and close the same page 500 times, but crashes after 145th time or so.

I will also update the original description accordingly.

[rolfbjarne]

If I add a GC.Collect between each iteration, the memory usage seems to stay stable. Can you try that and see if something changes on your end? I'm not suggesting this as something you should actually do in the app, it's just to help diagnose the problem.

Unfortunately I haven't been able to use memory profiling with Instruments on your app, for some reason the code Instruments injects in the app to profile memory ends up crashing the app. Would it be possible to create a test project without MAUI to see if Instruments likes that better, or does your code require MAUI?

[janne-hmp]

Actually, Matt Leibowitz has most likely already fixed this in the forthcoming version of SkiaSharp. The problem on iOS was that there were circular references between PlatformView and its Maui control, preventing garbage collection on iOS. Also Jonathan Peppers knows more. I've been waiting for the new version to come out before closing this issue.

[rolfbjarne]

Unfortunately I haven't been able to use memory profiling with Instruments on your app, for some reason the code Instruments injects in the app to profile memory ends up crashing the app. Would it be possible to create a test project without MAUI to see if Instruments likes that better, or does your code require MAUI?

Actually nvm about this part, I disabled the interpreter and now Instruments work