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[Solved] Is this memory leak?

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King Chan asked on 13 Sep 2010, 06:23 PM

Dear Telerik Staff,

I wonder if I did the garbage collection incorrectly, or this is memory leak?
I spent few days to research about Silverlight's memory leak issues and I know it affected Telerik's controls as well, I just want to see if this is caused by same reason or it is just the way I do the garbage collection was wrong.

The demo I created is very simple, Button "Create Obj" will create 10 RadScheduler and add into LayoutRoot and to a List<RadScheduler>.

Then the Button "Collects" will run though the List<RadSchdeduler> to remove each RadScheduler from LayoutRoot, then set each RadScheduler object to null, Clear() the list, then do the:

GC.Collect();
GC.WaitForPendingFinalizers();
GC.Collect();

1) Before Click Create Obj Button:
Task Manager:
IExplorer.exe
Memory(Private Working Set): 42,828k
Performance Memory: 656MB

2) After Click Create Obj Button:
Task Manager:
IExplorer.exe
Memory(Private Working Set): 194,828k
Performance Memory: 805MB

3) After Click "Collect" Button:
Task Manager:
IExplorer.exe
Memory(Private Working Set): 194,280k
Performance Memory: 801MB

For same scenario, if I create Button obj(500 Buttons) instead of RadScheduler, I can see the memory increased few MB and released few MB properly.
But again, for same scenario, if I create RadDialog(10 RadDialog with no Content) obj this time instead of RadScheduler, then I close it, null it, GC.Collect it, it will release PART OF the memory, and have around 1 MB didn't release.

And here is the demo code (everything created in MainPage.xaml.cs):

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 Telerik.Windows.Controls;

using System.Reflection.Emit;

using System.Diagnostics;

namespace RadControlsSilverlightApp4

{

public partial class MainPage : UserControl

{

TextBlock aLabel = new TextBlock();

List<RadScheduler> SchedulerList = new List<RadScheduler>();

public MainPage()

{

InitializeComponent();

this.LayoutRoot.ColumnDefinitions.Add(new ColumnDefinition { Width = new GridLength(100, GridUnitType.Auto) });

this.LayoutRoot.ColumnDefinitions.Add(new ColumnDefinition { Width = new GridLength(100, GridUnitType.Pixel) });

this.LayoutRoot.RowDefinitions.Add(new RowDefinition { Height = new GridLength(100, GridUnitType.Auto) });

this.LayoutRoot.RowDefinitions.Add(new RowDefinition { Height = new GridLength(70, GridUnitType.Auto) });

this.LayoutRoot.RowDefinitions.Add(new RowDefinition { Height = new GridLength(500, GridUnitType.Auto) });

Button aButton = new Button();

aButton.Content = "Create Objs";

aButton.SetValue(Grid.RowProperty, 0);

aButton.SetValue(Grid.ColumnProperty, 0);

this.LayoutRoot.Children.Add(aButton);

Button aCollectButton = new Button();

aCollectButton.Content = "Collects";

aCollectButton.SetValue(Grid.RowProperty, 1);

aCollectButton.SetValue(Grid.ColumnProperty, 0);

this.LayoutRoot.Children.Add(aCollectButton);

aLabel.SetValue(Grid.RowProperty, 1);

aLabel.SetValue(Grid.ColumnProperty, 1);

aLabel.Text = GC.GetTotalMemory(true).ToString();

this.LayoutRoot.Children.Add(aLabel);

Button aUpdateButton = new Button();

aUpdateButton.Content = "Update";

aUpdateButton.SetValue(Grid.RowProperty, 2);

aUpdateButton.SetValue(Grid.ColumnProperty, 0);

this.LayoutRoot.Children.Add(aUpdateButton);

aButton.Click +=new RoutedEventHandler(aButton_Click);

aCollectButton.Click +=new RoutedEventHandler(aCollectButton_Click);

aUpdateButton.Click += new RoutedEventHandler(aUpdateButton_Click);

}

public void aButton_Click (object sender, RoutedEventArgs e){

Debug.WriteLine("Create 10 Obj");

for (int i = 0; i < 10; i++)

{

RadScheduler aScheduler = new RadScheduler();

aScheduler.SetValue(Grid.RowProperty, 3);

aScheduler.SetValue(Grid.ColumnProperty, 1);

SchedulerList.Add(aScheduler);

this.LayoutRoot.Children.Add(aScheduler);

}

aLabel.Text = GC.GetTotalMemory(false).ToString();

Debug.WriteLine("Obj Count: " + SchedulerList.Count.ToString());

Debug.WriteLine("Obj Count: " + this.LayoutRoot.Children.Count.ToString());

}

public void aCollectButton_Click(object sender, RoutedEventArgs e)

{

for (int i = 0; i < SchedulerList.Count; i++)

{

this.LayoutRoot.Children.Remove(SchedulerList[i]);

SchedulerList[i].DataContext = null;

SchedulerList[i] = null;

}

SchedulerList.Clear();

Debug.WriteLine("Collect!");

GC.Collect();

GC.WaitForPendingFinalizers();

GC.Collect();

Debug.WriteLine("Collected!");

Debug.WriteLine("Obj Count: " + SchedulerList.Count.ToString());

Debug.WriteLine("Obj Count: " + this.LayoutRoot.Children.Count.ToString());

aLabel.Text = GC.GetTotalMemory(false).ToString();

}

public void aUpdateButton_Click(object sender, RoutedEventArgs e)

{

Debug.WriteLine("Update!");

Debug.WriteLine("Obj Count: " + this.LayoutRoot.Children.Count.ToString());

aLabel.Text = GC.GetTotalMemory(false).ToString();

}

=========
Update: I just used WeakReference to check, I realize none of the RadScheduler get collected, they are all Alive.
And for the RadDialog, I can see few of the RadDialog object is Alive, and others was got collected, it happens if I try keep clicking Create and Collect frequently. (i.e Created like 500 RadDialog on screen, after collects, there is 3 alives)
=========
Thanks for your help,
King

3 Answers, 1 is accepted

Accepted

answered on 14 Sep 2010, 07:50 AM

Hello King Chan,

Unfortunately Silverlight 4 GDR1 did not fix all memory leaks. We are in a process of preparing Q2 Service Pack 2 (which workarounds known framework leaks and also fix few memory leaks caused by our code).
It will be official in a week or two.

Let us know if you need more information.

Greetings,
Hristo
the Telerik team

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