Memory leaks due to Garbage Collector not disposing controls with nested external controls

[dfernandezramos]

Describe the bug

Garbage Collector is not disposing Avalonia controls containing nested controls coming from another UserControl classes and turned invisible resulting on memory leaks.

To Reproduce

Steps to reproduce the behavior:

1. Run the AvaloniaLeakSample application git@github.com:LongoMatch/AvaloniaLeakSample.git
2. Click on the 'Move to view 2' button
3. Click on the 'BACK' button
4. Repeat steps 2 & 3 several times until GC disposes unused objects

Expected behavior

Mind the application output. View2 is not being destroyed. You should see "There is no leak on view 1" and "There is no leak on view 2" messages several times but only "There is no leak on view 1" is being displayed.

Screenshots

Environment

• OS: Tested on macOS Sonoma and Windows 10
• Avalonia-Version: 11.0.5

Additional context

Important information:

• Leak on "View 2" happens when using <sample:NestedControl1> (which just contains a button) AND setting NestedControl.IsVisible = false; on the code behind at the OnInitialized () method.
• Leak also happens when using <sample:NestedControl1> AND setting its IsVisible="False" property on the XAML file.
• Not setting <sample:NestedControl1> as invisible or if we just use a <Button> instead does not leak even if we set that button as not visible on the code behind at the OnInitialized () method or the XAML file.
• It seems it just happens with the button control. Changing <Button> for <Rectangle> or other controls in the nested control class does not produce the leak

[dfernandezramos]

As a note: we have seen that the latest Avalonia nightly build 11.1.999-cibuild0042640-beta is not reproducing this issue anymore. Maybe could you check this and try to port the fix to the next minor release?

Thanks a lot in advance

[timunie]

if it works in nightly, we can close this ticket imo. If that PR will be / can be backported to 11.0.6, I cannot guarantee.

[ylatuya]

@timunie could you please provide a link to the PR that fixes this memory leak? It's leaking the whole view and therefore all objects referenced by that view, including the ViewModel. I have been unable to find the PR from the commits lists and I would like to know if it has been backported or if it was labeled as backport-candidate-11.0.x.

Thanks!

[jp2masa]

There are at least 3 PRs to fix memory leaks that were backported to 11.0.x: https://github.com/AvaloniaUI/Avalonia/pulls?q=is%3Apr+sort%3Aupdated-desc+memory+leak+label%3Abackported-11.0.x+is%3Aclosed.

There also seems to be a new git tag for 11.0.6, so it may be released soon. The 11.0.6 packages appear in the nightly feed, if you want to test.

[ylatuya]

Thanks for the link. I did a similar search and I couldn’t find one that fits the same use case. Looking into more details I think #13529 might be the fix that we are looking for.

I didn’t know 11.06 was in the nightly builds, let’s see if it’s fixed in this release.

[dfernandezramos]

JFYI: Upgraded to Avalonia 11.0.6 on the sample app and the leak is still happening

[timunie]

@dfernandezramos that means you have to wait for 11.1 or use nightly.

[maxkatz6]

Unrelated to the leak, but: don't use finalizers or IDisposable in your controls. It's not reliable, and controls are not disposed ever (but still should be garbage collected).
Instead, use atteched/detached from visual tree events/overrides if you need to initialize or release your unmanaged resources.

[maxkatz6]

Checked where this issue was fixed on master.
Seems like it's not reproducible since #12861
Added to the backport list.