NET5.0.9 ListView BackgroundImage GDI object leak

[vsfeedback]

This issue has been moved from a ticket on Developer Community.

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[severity:I'm unable to use this version]
When a win forms app shows a form with a ListView Control that has its BackgorundImage set it does not release 3 GDI objects each time it is disposed and Garbage collected, this is causing major memeory leaks in our application.

Attached is a sample application to demonstrate the issue.

All I did to re-create this, is the following.

1. Create a new winforms application

   
   

2. Add a new form so you have a Form1 and a Form2.

   

3. Add two buttons on Form1, one to garbage collect, and one to open Form2.

       private void btnGarbageCollect_Click(object sender, EventArgs e)
   	{
   		GC. Collect();
   	}
   
       private void btnOpenFormWithListView_Click(object sender, EventArgs e)
   	{
   		Form2 oForm = new Form2();
           oForm.Show();
   	}

4. On Form2 add a listview and set a backgroup image from a resource.

   

5. Open Task manager with the GDIObjects coulmn enabled, and keep opening and closing from 2 from the app and garbage collecting, you will see a jump of 3 GDI objects each time you open and close the form.

   

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Original Comments

Feedback Bot on 9/8/2021, 09:25 AM:

We have directed your feedback to the appropriate engineering team for further evaluation. The team will review the feedback and notify you about the next steps.

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Original Solutions

Marie Shi [MSFT] solved on 9/8/2021, 05:09 PM, 0 votes:

We moved this issue to a relevant GitHub project. Please comment and track it at this URL: dotnet/core#6667

[Marie-Shi]

More info:

1. This is not a regression issue, it can repro in .Net Framework, also can repro in .NET 3.1, 5.0& 6.0.
2. This issue cannot repro in imageList.

Repro Steps:

1. Extract the attachment “BackGroundImageIssue.zip” and open it in VS.
   BackGroundImageIssue.zip
2. Open Task manger, select the 'Details' tab and add GDI objects column if not already visible.
3. Build and run the application, click ‘Open Form With List View’ button to open Form2 then close Form2, then click ‘Garbage Collect’ button, repeat this operation several times.

Actual behavior:
The number of GDI objects are increasing.

Expected behavior:
"GDI objects" don't increase.

[weltkante]

The GDI handles are leaked every time a BackgroundImage is assigned (given the ListView handle is already created). I've made a memory snapshot comparison and there seem to be no managed objects leaked. Needs investigation of what happens on the native level, I'll continue looking into it, but it may not be fixable on WinForms level if simple reassignment already leaks the previous images handles. Also explicitly clearing the image by sending LVM_SETBKIMAGE with LVBKIF_SOURCE_NONE does not prevent the handle leak.

[RussKie]

Are you able to check if MFC exhibiting the same issue?

[weltkante]

Good point reminding me, wanted to do that earlier but somehow slipped my mind.

The behavior is really surprising, a plain MFC setup doesn't leak, nor simply sending LVM_SETBKIMAGE manually in .NET. I'll try figuring out what WinForms does differently because on a first glance there isn't anything it can do wrong: it simply sends a window message with a filename, there isn't even an image handle involved.

[weltkante]

Oh wow, this has nothing to do with the native ListView at all. Winforms ListView.GenerateRandomName uses Bitmap.GetHIcon to generate a seed for a randomizer and never releases that handle ... that is really weird code, I didn't even expect to look in the file name generator for an image leak. I'll create a PR to simplify this.