Memoryleak VisualstateManager in ButtonStyle on Android

[Larhei]

Description

When creating an explicite Button Style in Styles.xaml like this.

<Style x:Key="MyButtonStyle" TargetType="Button"> <Setter Property="VisualStateManager.VisualStateGroups"> <VisualStateGroupList> <VisualStateGroup x:Name="CommonStates"> <VisualState x:Name="Normal" /> <VisualState x:Name="Pressed"> </VisualState> <VisualState x:Name="Disabled"> </VisualState> </VisualStateGroup> </VisualStateGroupList> </Setter> </Style>

And referencing it on any ContentenPage like this
<Button x:Name="PART_MyButton" Style="{StaticResource MyButtonStyle}" Text="Welcome to .NET MAUI!" VerticalOptions="Center" HorizontalOptions="Center" />

The ContentPage never get garbage collected on Android.

Steps to Reproduce

1. Checkout the code
2. Start the App on Android
3. Navigate to Leak by pressing Button "Leak"
4. Navigate back
5. Hit GC Button multiple Time to force GC

Link to public reproduction project repository

https://github.com/Larhei/Maui-Issues/tree/main/VisualStateLeak

Version with bug

8.0.10 SR3

Is this a regression from previous behavior?

Not sure, did not test other versions

Last version that worked well

Unknown/Other

Affected platforms

Android

Affected platform versions

No response

Did you find any workaround?

Moving the Style to ContentPage.Resources will stop the leak, but with will force me to copy my styles in multiple locations.

Relevant log output

No response

[MitchBomcanhao]

speaking of workarounds, just wondering: what if instead of using the style directly on each page, you import a smaller resource dictionary which includes the necessary button style into the page? if that works (ie it doesn't still trigger a memory leak), it'd get rid of multiple copies of the style.

[Larhei]

@MitchBomcanhao
I also tested this... Not working :-(
Even when doing code behind Code that is clearing resources after navigating away and clearing Visual States Group on the Button instance

[PureWeen]

@jonathanpeppers @StephaneDelcroix thoughts?

[StephaneDelcroix]

I'll check if this is Android specific or a general issue. VSM or Style might be holding a stronger-than-necessary ref to the Label...

[jonathanpeppers]

This app seems like it is working for me on both Windows & Android:

[0:] NotLeakingPage finalized.
[0:] LeakingPage finalized.

@Larhei did you disable XAML hot reload when testing this? (otherwise it can keep things alive)

• https://aka.ms/maui-memory-leaks
• https://learn.microsoft.com/visualstudio/xaml-tools/xaml-hot-reload-impact-performance

[Larhei]

I will retest and get back to you Gesendet von meinem Windows-10 Gerät.

…

________________________________ Von: dotnet-policy-service[bot] ***@***.***> Gesendet: Tuesday, March 26, 2024 10:13:35 PM An: dotnet/maui ***@***.***> Cc: Lars Heinrich ***@***.***>; Mention ***@***.***> Betreff: Re: [dotnet/maui] Memoryleak VisualstateManager in ButtonStyle on Android (Issue #21389) Hi @Larhei<https://github.com/Larhei>. We have added the "s/needs-info" label to this issue, which indicates that we have an open question for you before we can take further action. This issue will be closed automatically in 7 days if we do not hear back from you by then - please feel free to re-open it if you come back to this issue after that time. — Reply to this email directly, view it on GitHub<#21389 (comment)>, or unsubscribe<https://github.com/notifications/unsubscribe-auth/ALLM2RLT5VIKMY3HZADCBWDY2HQH7AVCNFSM6AAAAABFDB4P6SVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZDAMRRGQ4DINBWGI>. You are receiving this because you were mentioned.Message ID: ***@***.***>

[Larhei]

@jonathanpeppers

Did a Test in release with dotnet gc-dump. Maybe I am reading this wrong... but I still can see LeakingPage in this dump... And this should not be the case from my understanding. Dump

[jonathanpeppers]

Do you see the log messages?

[0:] NotLeakingPage finalized.
[0:] LeakingPage finalized.

If you push/pop the pages a few times and click GC multiple times? I was just tapping quicly and noticed those messages printed.

The file just shows 1 instance:

It should grow to several instances if there is an issue.

[Larhei]

Hi @jonathanpeppers, how comes this instance is holding multiple button instances? See latest dump file in the repro? Or how comes no instance of the not leaking page is showing even when navigated to that page? I am confused

[StephaneDelcroix]

<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
                    xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
                    x:Class="Microsoft.Maui.Controls.Xaml.UnitTests.Maui21839">
    <Button x:Name="button" Text="Click me" Style="{StaticResource buttonStyle}"/>
</ContentPage>

            Application.Current.Resources.Add("buttonStyle", 
                new Style(typeof(Button)) {
                    Setters = {
                        new Setter { Property = VisualStateManager.VisualStateGroupsProperty, Value = new VisualStateGroupList{
                            new VisualStateGroup {
                                Name = "CommonStates",
                                States = {
                                    new VisualState { Name = "Normal" },
                                    new VisualState { Name = "Pressed" },
                                    new VisualState { Name = "Disabled" }
                                }
                            }
                        } }
                    }
                });
            var pagewr = new WeakReference(new Maui21839(useCompiledXaml));
            await Task.Delay(10);
            GC.Collect();
            Assert.IsNull(pagewr.Target, "Page leaked");

I can confirm that it leaks

[Larhei]

@jonathanpeppers and @StephaneDelcroix
Thanks for taking you time and investigating this.