Q3 2010 Memory Leak?

[Adam]

I've read the threads on the RadComboBox memory leak stemming from the well known SL4 memory leak. Are there any known issues with leaks on the SL4 SP1 / Telerik 2010.3.1314.1040 RadComboBox?

We experience leaks when using the control in a DataTemplate for a CellTemplate in a RadGridView. The data template is a static resource on the page and the items source is an observable collection that contains hundreds of business objects.

Without going into too much more detail I was just wondering if this was a known issue. Thanks!

-Adam

[Valeri Hristov]

Hello Adam,

We are not aware of new memory leaks in RadComboBox that appeared recently. We strongly recommend testing with the latest Silverlight runtime (GDR3) and if the problem persists, we will need a simple project that could be used to trace memory leak. After that we will do our best to provide a fix as soon as possible.

Kind regards,
Valeri Hristov
the Telerik team

[Adam]

I am using GDR3, I mistakenly called it SP1.

I have a project that reproduces the issue. See the RadGridView below. Each time the user clicks to open a new drop down in the grid the private bytes jumps significantly (I have 584 strings in the Birds ObservableCollection). The bytes are never reclaimed. 

<UserControl xmlns:telerik="http://schemas.telerik.com/2008/xaml/presentation"  x:Class="MemoryLeakTest.MainPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d"
    d:DesignHeight="300" d:DesignWidth="400">
 
	<UserControl.Resources>
		<ContentControl x:Key="BaseContent" />
		<DataTemplate x:Key="BirdPicker">
			<telerik:RadComboBox 
				ItemsSource="{Binding Source={StaticResource BaseContent}, Path=DataContext.Birds}"
				SelectedValue="{Binding Path=Bird}"
			/>
		</DataTemplate>
	</UserControl.Resources>
	<Grid>
		<telerik:RadGridView ItemsSource="{Binding BizObjs}" AutoGenerateColumns="False">
			<telerik:RadGridView.Columns>
				<telerik:GridViewDataColumn CellTemplate="{StaticResource BirdPicker}" DataMemberBinding="{Binding Bird}" />
			</telerik:RadGridView.Columns>
		</telerik:RadGridView>
	</Grid>
</UserControl>

[Valeri Hristov]

Hi Adam,

I noticed that you have a ContentControl as a static resource, that seems to provide data context in the BirdPicker data template. This is not typical usage and might be causing the leak. Unfortunately without a complete project for debugging, I cannot say what's the real cause for the problem.

All the best,
Valeri Hristov
the Telerik team

[Adam]

The static resource is a little trick we all learned to slow the leak inherent in the SL4 runtime. If you hadn't heard about it, read this for a laugh: http://forums.silverlight.net/forums/t/171739.aspx

Anyway, that static resource work around has become second nature, and while I agree it is not "typical usage", it is legal and should not (to my understanding) place us in uncharted territory.

My colleague is sending you a toy project to demonstrate the problem. The only way I can stem the leak is to employ the virtualizing feature of RadComboBox. 

Thanks for taking a look.

-Adam

[Valeri Hristov]

Hi Adam,

I received an application from Neil, I guess he is your colleague. I CC-ed you in his support ticket.

Regards,
Valeri Hristov
the Telerik team

[Adam]

Thank you for pointing out our oversight - The cell template's lifespan (and everything inside it) will always be equal to the Grid's. We need to quit being lazy and start using cell edit templates.

No Leak!!