Microsoft-ui-xaml: Navigation Memory Leak

[mhmd-azeez]

Describe the bug
We have noticed that our UWP apps have memory leaks. I have investigated it and found out that when navigating to new pages, the memory gets higher and doesn't seem to go down by much even when GC runs. The pages do get garbage collected (Their finalizer is run), but it seems like some kind of unmanaged memory is not properly cleaned up.

Steps to reproduce the bug

I have put together a small repro that consists of two pages:

1. MainPage

<Page>
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="70" />
            <RowDefinition  />
        </Grid.RowDefinitions>

        <Button x:Name="navigateButton" Content="Navigate" HorizontalAlignment="Center"
                    Click="NavigateButton_Click" />

        <Frame x:Name="mainFrame" IsNavigationStackEnabled="False"
               Padding="10" Grid.Row="1" />
    </Grid>
</Page>

    public sealed partial class MainPage : Page
    {
        public MainPage()
        {
            this.InitializeComponent();
        }

        private void NavigateButton_Click(object sender, RoutedEventArgs e)
        {
            mainFrame.Navigate(typeof(Page1), null, new Windows.UI.Xaml.Media.Animation.DrillInNavigationTransitionInfo());
        }
    }

1. Page1:

<Page>
    <VariableSizedWrapGrid ItemWidth="100" ItemHeight="60">
        <Button Padding="20, 10" Content="Hello!"/>
        <Button Padding="20, 10" Content="Hello!"/>
        <Button Padding="20, 10" Content="Hello!"/>
        <Button Padding="20, 10" Content="Hello!"/>
        <Button Padding="20, 10" Content="Hello!"/>

        <!-- And 25 more buttons here -->
    </VariableSizedWrapGrid>
</Page>

    public sealed partial class Page1 : Page
    {
        public Page1()
        {
            this.InitializeComponent();
        }

        ~Page1()
        {
            Debug.WriteLine("Page dead :(");
        }
    }

The full source code is available on GitHub.

I have also tried out setting Frame.IsNavigationStackEnabled to false, it doesn't help.

What am I doing wrong here?

Expected behavior
Memory is reclaimed after Garbage collector runs

Screenshots

And you can see a video of the repro.

Version Info
NuGet package version:
N/A (Not using WinUI)

| Windows 10 version | Saw the problem? |
| :--------------------------------- | :-------------------- |
| Insider Build (xxxxx) | |
| May 2019 Update (18362) | Yes |
| October 2018 Update (17763) |Yes |
| April 2018 Update (17134) | |
| Fall Creators Update (16299) | |
| Creators Update (15063) | |
| Anniversary Update (14393) | |

| Device form factor | Saw the problem? |
| :-------------------- | :------------------- |
| Desktop | Yes |
| Mobile | |
| Xbox | |
| Surface Hub | |
| IoT | |

Additional context

[jevansaks]

This issue is also cross-posted to https://stackoverflow.com/questions/56675628/uwp-navigation-memory-leak. We can investigate as a platform bug and report back to stack overflow when we understand this.

@MikeHillberg can you debug this repro?

[r7dev]

I also have this problem with the same settings cited.

[r7dev]

@Opiumtm explain it here, but it doesn't demonstrate the code.

[cheles]

I leave my comment here, although it's an old post, for others that might search for it.

We made huge improvements in memory handeling and GC calls with latest UWP 6.2.9 Nuget update while targeting >=RS4 . The complete release notes are here: https://github.com/microsoft/dotnet/blob/master/releases/UWP/net-native2.2/README.md

[mhmd-azeez]

@cheles I am not using WinUI currently, is there a way for me to use these latest changes?

[cheles]

@encrypt0r Microsoft.NETCore.UniversalWindowsPlatform is the default package for any UWP application. aren't you using this package?

[mhmd-azeez]

@cheles I actually do! Thanks, that's great to hear and I hope you continue these optimizations

[cheles]

cool. test it and let us know if we can close this one out.

[mhmd-azeez]

@cheles unfortunately, it doesn't seem to help with the repro. I have disabled NavigationStack on the frame and yet, no memory is reclaimed after 3 garbage collections.

[florian-alexandre]

Hi !
Any news about this problem please ?

[cheles]

@encrypt0r are you debugging a Debug build or Release? GC is implemented differently and, in general, it's an expensive. In Release you will see GC being called more rarely than Debug.

93 MB out of, probably 3/4GB or RAM is not dangerously enough to cause GC to clean gen 0/1/2 objects. I've tried your sample in Debug and I've barely got to 80 MB after 80+ clicks.
Try and see if you manage to reach at least 100MB+ or create an UI test with [WinAppDriver ] (https://github.com/microsoft/WinAppDriver/tree/master/Tests/UWPControls) to reach a higher memory consumption and observe GC calls

[kmgallahan]

Along the lines of what @cheles mentioned, I'd recommend you give this article a read. In particular item 4 of "What Causes Memory Leaks?".

[cheles]

Also, if you want a more in-depth way to inspect memory consumption & GC calls, use Performance Monitor (Win10 built-in) https://devblogs.microsoft.com/dotnet/gc-performance-counters/

[CodeForCSharp]

@cheles This problem has existed for a long time and has not been solved, even with the updated Microsoft.NETCore.UniversalWindowsPlatform to lastest.
I've seen a lot of people mention things like this. such as https://github.com/dotnet/runtime/issues/12255.
Look at the last few replies,from the snapshot,ConditionalWeakTable leak memory.
In other case,it is not necessary to switch pages. Frequent remove and add interface elements can also cause this problem.
We don't know what's going on inside, but that's how it shows.

[cheles]

@CodeForCSharp I haven't said that UWP team fixed all memory issues in UWP. I just said that UWP 6.2.9 brought some memory consumption improvements per this link

Adjust garbage collection timing during interop to eliminate memory increase in UWP app when navigating between pages

https://github.com/dotnet/runtime/issues/12255 seems to have been marked for Future release but I don't see any due date to it.

[CodeForCSharp]

@cheles Thank you for your work.I know it's getting better.
Many questions about UWP are usually unanswered, which is very disturbing.
UWP Framework also have many memory issues.Hope to fix it as soon as possible.

[abk90007]

@cheles, I am using latest version 6.2.10, and still facing this memory leak issue, which leads to app memory to 1 GB.
Is there any fixed date for the resolution of this issue?