ListView/CollectionView memory leak under Windows

[hbraasch]

Description

A simple repro (see link below) demonstrates a ListView/CollectionView memory leak under Windows.
Each time the ItemSource gets updated with the exact same list, the app memory usage increases.
The repro is a simplification, normally the ListView/CollectionView gets filled through a binding. However the repro still demonstrates the same problem.

See this video for a demonstration:

ListviewMemoryTester.mp4

I'm a VS Community user so do not have access to the Xamarin Profiler to see if the problem also exists in Android and iOS.

Steps to Reproduce

1. Open the app from the repro in VS: https://github.com/hbraasch/ListViewMemoryTester.git
2. Set the platform to [Windows] and run
3. Click on the refresh button in the toolbar, see how the memory usage increases
4. Click on the [Click to launch [CollectionView] page] button, which launches the page based on a CollectionView
5. Click on the refresh button in the toolbar, see how the memory usage also increases

Version with bug

6.0.408 (current)

Last version that worked well

Unknown/Other

Affected platforms

Windows

Affected platform versions

net6.0-windows10.0.19041.0

Did you find any workaround?

No

Relevant log output

No response

[jfversluis]

Thanks for the report and investigation on this!

I'm not necessarily the expert on performance testing, but what happens if you try calling the garbage collector? I can imagine that memory might still be growing depending on the memory that is available on the system and only flushed whenever necessary?

Besides this repro do you have any real-world scenarios where you had this happening? What made you start investigating this?

Hi @hbraasch. 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.

[hbraasch]

Hi @jfversluis

When add the following code to the [Refresh] event, it now tries to force a GC before updating the ImageSource.

ToolbarItems.Add(new ToolbarItem("Refresh", "ic_refresh.png", () => {
    GC.Collect();
    listView.ItemsSource = GenerateDisplayItems();
}));

The small yellow dots on the memory graph shows where the GC's occurs. They do happen where expected. Unfortunately it still shows the memory growth

My real-world application... I'm developing a custom TreeView which inherits from a ListView. It appears to work well when running under Android and iOS (but I must admit I did not check for memory leaks as I do not have the tools - I think). But when I started testing for Windows, the Windows app crashes with an out-of-memory exception.

Since VS shows a memory graph while running a Windows app, I quickly noticed the continuous increase in memory each time e.g. a row gets expanded/collapsed, which is done by simply replacing the listview's ItemSource with a newly calculated (but mostly similar sized) one.

To investigating this further I started with a simple app (the repro), and found that it shows the same disconcerning effect.

I might be barking at the wrong tree, but I though I need to raise this before wasting an enormous amount of time searching for bugs elsewhere.

Regards