[Solved] RadGridView releasing memory?

[Jim]

The garbage collector doesn't appear to be able to free my RadGridViews once I set their ItemsSource to an ObservableCollection.

Perhaps I am not really executing things correctly so I am hoping you can set me straight on this.  I created a very simple project that demonstrates my problem.  Unfortunately even a simple project is a lengthy post, so I appologize in advance for that.

btw: I am using the silverlight 3 controls, version 2009.1.529.1020

The project simply adds a UserControl that contains a RadGridView which binds to a very simple two property class.  A button allows you to add one of these UserControls and another button removes it.  Theoritically if you punch add, add, add, then remove, remove, remove, then garbage collect (also a button) you should be able to fire up WinDBG and notice that there are no instances of the class TestGarbage.AGridView in the heap. Unfortunately this is not what I see... HELP?

Here are the !DumpHeap -type TestGarbage.AGridView results from doing the previously mentioned steps:

0:026> .loadby sos coreclr
0:026> !dumpheap -type TestGarbage.AGridView
...
 Address       MT     Size
0482f6a8 06bd70a4       84
048e8cec 06bd70a4       84
049e6f60 06bd70a4       84
total 3 objects
Statistics:
      MT    Count    TotalSize Class Name
06bd70a4        3          252 TestGarbage.AGridView

And the !gcroot on the first item 0482f6a8

0:026> !gcroot 0482f6a8
Note: Roots found on stacks may be false positives. Run "!help gcroot" for
more info.
Scan Thread 8 OSTHread f9c
Scan Thread 24 OSTHread 10d4
Scan Thread 25 OSTHread 7ec
DOMAIN(02E9F5A8):HANDLE(Pinned):6be12f8:Root:  05814260(System.Object[])->
  04820230(System.Collections.Generic.Dictionary`2[[System.IntPtr, mscorlib],[System.Object, mscorlib]])->
  05818170(System.Collections.Generic.Dictionary`2+Entry[[System.IntPtr, mscorlib],[System.Object, mscorlib]][])->
  048799b4(MS.Internal.ManagedObjectReference)->
  0486cb40(Telerik.Windows.Data.FieldFilterDescription)->
  0486cbe8(Telerik.Windows.Data.RadObservableCollection`1[[Telerik.Windows.Data.FilterDescriptor, Telerik.Windows.Data]])->
  0486ccc4(System.Collections.Specialized.NotifyCollectionChangedEventHandler)->
  0486ccac(System.Object[])->
  0486cc8c(System.Collections.Specialized.NotifyCollectionChangedEventHandler)->
  048656f4(Telerik.Windows.Controls.GridView.FilteringDropDown)->
  048659a8(System.Windows.Controls.Grid)->
  04865608(System.Windows.Controls.Grid)->
  04865aa4(System.Windows.Controls.Grid)->
  0486351c(Telerik.Windows.Controls.GridView.GridViewHeaderCell)->
  04830a84(Telerik.Windows.Controls.RadGridView)->
  0484574c(System.Windows.Controls.Grid)->
  0482f6a8(TestGarbage.AGridView)->

The code follows ( I can also send a .RAR file that contains the project if that helps)

XAML for User Control that has the grid in it:

<UserControl x:Class="TestGarbage.AGridView"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:telerikGrid="clr-namespace:Telerik.Windows.Controls;assembly=Telerik.Windows.Controls.GridView"
    Loaded="UserControl_Loaded">
    <Grid x:Name="LayoutRoot" Background="White">
        <telerikGrid:RadGridView x:Name="cGridView" >
            <telerikGrid:RadGridView.Columns>
                <telerikGrid:GridViewDataColumn HeaderText="ID" DataMemberBinding="{Binding ID}" Width="Auto"/>
                <telerikGrid:GridViewDataColumn HeaderText="Name" DataMemberBinding="{Binding Name}" Width="Auto" />
            </telerikGrid:RadGridView.Columns>
        </telerikGrid:RadGridView>
    </Grid>
</UserControl>

.CS for same User Control

using System;
using System.Collections.ObjectModel;
using System.Windows.Controls;
using System.Windows;

namespace TestGarbage
{
    public partial class AGridView : UserControl
    {
        public AGridView()
        {
            InitializeComponent();
        }

        private void UserControl_Loaded(object sender, RoutedEventArgs e)
        {
            var coll = new ObservableCollection<Simple>();
            coll.Add( new Simple { Name = "First", ID = "1" });
            coll.Add(new Simple { Name = "Second", ID = "2" });
            cGridView.ItemsSource = coll;
        }
    }
}

.XAML for MAINPAGE in a new application

<UserControl x:Class="TestGarbage.MainPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:telerikGrid="clr-namespace:Telerik.Windows.Controls;assembly=Telerik.Windows.Controls.GridView"
    xmlns:local="clr-namespace:TestGarbage"
    Width="400" Height="300">
    <StackPanel x:Name="LayoutRoot" Background="White" Orientation="Vertical">

        <Button Content="Add Control" Click="AddOne" />
        <Button Content="Remove OK" Click="RemoveOK" />

        <Button Content="Collect Garbage" Click="OnCollect" />
        <StackPanel x:Name="cStack" Orientation="Vertical" />
    </StackPanel>
</UserControl>

.CS for MAINPAGE

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;
using System.Collections.ObjectModel;

namespace TestGarbage
{
    public partial class MainPage : UserControl
    {
        public MainPage()
        {
            InitializeComponent();
        }

        private void
        AddOne(object sender, RoutedEventArgs e)
        {
            var control = new AGridView();

            cStack.Children.Add( control );
        }

        private void
        OnCollect(object sender, RoutedEventArgs e)
        {
            GC.Collect();
            GC.WaitForPendingFinalizers();
        }

        private void RemoveOK(object sender, RoutedEventArgs e)
        {
            cStack.Children.RemoveAt( cStack.Children.Count -1 );

        }
    }
}

[Hristo Deshev]

Hello Jim,

I have reproduced and confirmed the leak -- thanks for the awesome report. I am still not sure why it is happening. The gcroot report tells us that there is a FieldFilterDescription object hung in memory that keeps a reference to a GridViewHeaderCell, which in turn keeps the RadGridView object in memory.

I find two things odd:

• That leak does not happen in Silverlight 2.
• The object keeping a reference to the FieldFilterDescription object is not a Telerik-created one -- it looks like a Silverlight-internal object.

I have a slight suspicion we might be dealing with a Silverlight 3 popup-related leak (Hey, it's still in beta!) as the filtering UI creates a popup control. We will be investigating that in greater detail.

In the mean time, the best I can offer is to disable filtering on RadGridView. That eliminates the leak.
Greetings,
Hristo Deshev
the Telerik team

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[Jim]

Great! The good news is I don't need this fixed until after Silverlight 3 is released :).  Mostly I wanted to figure out if there was something I was doing incorrectly.  I am confident you guys will either fix it (if it is yours) or that it will be resolved by the silverlight team at MS.