After certain action (pressing a button that starts a sequence of calculations) in the WPF-application a memory leak occurs (it is visible in the task manager in vm size section) approximately on 10 mbytes after each pressing of the button.
The sequence of calculations does not contain errors.
The use of memory profiler (.NET Memory Profiler) has shown that leaks in .net are not present, but after each pressing of the button the memory size shown in Name/Resource section (marked HeapMemory) increases approximately by 10 mbytes.
I've read posts about leaks in WPF but those are not my case definately.
What can be wrong? Any suggestions? Maybe, someone had the same problem?
Seeing an increase in the used memory is a misnomer in .NET for detecting a memory leak.
It is easy to make a memory leak in WPF, however. I would suggest using a slightly more visual tool like Redgate Ants Memory Profiler (14 day free trial). Use this method to test for leaks:
Press the button once (to eat up any warmup you might have)
Take a snapshot
Press the button again
Take a snapshot
When you go to the "Class List" and check the filter for "From current snapshot show: only new object". This should give you a better picture of whether you have objects that will never be let go.
The other thing about Ants Memory Profiler is that it has links to videos everywhere that instruct you on how to find a leak. Tracking down leaks is a bit of a black art and it's nice to have help.
No, I don't work for Redgate :)
Perhaps you need to use the WeakEvent Pattern as documented on MSDN to avoid leaks?
Listening for events can lead to memory leaks. The typical technique for listening to an event is to use the language-specific syntax that attaches a handler to an event on a source. For instance, in C#, that syntax is: source.SomeEvent += new SomeEventHandler(MyEventHandler).
This technique creates a strong reference from the event source to the event listener. Ordinarily, attaching an event handler for a listener causes the listener to have an object lifetime that influenced by the object lifetime for the source (unless the event handler is explicitly removed). But in certain circumstances you might want the object lifetime of the listener to be controlled only by other factors, such as whether it currently belongs to the visual tree of the application, and not by the lifetime of the source. Whenever the source object lifetime extends beyond the object lifetime of the listener, the normal event pattern leads to a memory leak: the listener is kept alive longer than intended.
(My emphasis.)
I could fix WPF Application memory leak issue by inserting in "thin" places GC.Collect().
Hope this help!
Related
I have a silverlight application in that when a form is opened it is using nearly 17mb but when i close the form it is releasing any memory . i am disposing all the variables and objects but GC is not releasing any thing . i also removed all the controls at runtime when closing form.
when i verified with ANTS Memory profiler . there it is showing as NativeObjectSafeHandle 196440 which is largest one that can be disposed and second largest is UnmanagedMemoryStream .
In memory profiler it is showing lot of silverlight internal references that iam not able to dispose them like styles, system.windows.controls and resources . Even though iam clearing form.resources.clear().
Pls suggest me in releasing the memory .
Thanks
krishna
The best practice is to not force a garbage collection in most cases. Since CLR knows best way to handle it. But if you really wanna force garbage collection try GC.Collect this will force immediate garbage collection of all generations
http://msdn.microsoft.com/en-us/library/xe0c2357(v=vs.110).aspx
Also please refer to the links i provided in comments for better explanation.
Working with WinForms you have to free memory after using gdi objects, event handlers, objects from native code, etc.
In WinForms I used to remove for example event handlers in the dispose method.
What is the best workaround to prevent memory leaks in Wpf? Is it the same as in Winforms using Dispose pattern? At all, do I have to care about event handlers, gdi objects in Wpf? What about the runtime created resources(Brushes, etc)?
This blog post lists the most common situations that cause memory leaks in WPF applications.
Event handlers to objects in parent windows
Registering to events from static objects
Using timers
Data binding
Changing the Text property of a text box
It also describes how to fix these common issues.
Another good approach is to develop an app while following the standard guidelines and then use some kind of profiler to determine any memory leaks or performance bottlenecks.
From MSDN: Any WPF framework-level element (those objects deriving from either FrameworkElement or FrameworkContentElement) has three common lifetime events: Initialized, Loaded, and Unloaded.
.....
Unloaded is raised last and is initiated by either the presentation source or the visual parent being removed. When Unloaded is raised and handled, the element that is the event source parent (as determined by Parent property) or any given element upwards in the logical or visual trees may have already been unset, meaning that data binding, resource references, and styles may not be set to their normal or last known run-time value.
Some helpful links on WPF resource dictionary leaks:
DynamicResource\StaticResource cause memory leaks
Memory leak problem with ResourceDictionary and MergedDictionaries
Watch out for events: it's very easy to miss something, because all references from the delegate will exist until the delegate lives. I suggest to use weak event pattern when it's possible. Actually Microsoft uses it in their Prism framework.
http://msdn.microsoft.com/en-us/library/aa970850.aspx
Also check out an issue that I was catched by many times when learning WPF http://support.microsoft.com/kb/938416/en-us
I am trying to pro-actively ensure I am not causing memory leaks in my code by keeping an extra weak reference to an object, and checking it is no longer active when it should be released (this is conditional code so it only runs when I am testing).
To simply reproduce the effect I am seeing, create a new WPF Application and put a Button on the main window. Create another window, and put a TextBox on it. In the click handler for the button, put the following code:
Window1 w = new Window1();
WeakReference weak = new WeakReference(w);
w.ShowDialog();
w = null;
// Equivalent to Application.DoEvents() just in case...
Application.Current.Dispatcher.Invoke(DispatcherPriority.Background, new Action(delegate { }));
GC.Collect();
GC.WaitForPendingFinalizers();
if (weak.Target != null)
MessageBox.Show("Memory Leak");
When you run this, click on the button and when the window displays, just click on the 'x' to close it and nothing happens - all good. Now do the same thing, but when the window displays, click into the TextBox and then click on 'x'. I get the "Memory Leak" message every time.
Ants Profiler shows System.Windows.Documents.TextEditor has a reference to the TextBox (which presumably gets set up only if you focus the TextBox), and the TextBox has a reference to the window. Its not a real memory leak because if you do the process multiple times, previous windows get collected, just not the latest. However, it means I cannot write tests that confirm memory is not leaking.
Am I the only person wanting this level of assurance, or is there another way?
I think some people have missed the point of your question. You're not trying to force GC's hand, but rather preemptively discover any memory leaks, and for that I applaud you.
In this particular case, it appears as though TextEditor (which is internal) is adding event handlers and has not yet had a chance to detach when your check runs. Have you tried explicitly shifting focus out of the closed window before pumping the dispatcher?
I think you will continue to run into these kind of issues if you attempt to do these tests in your application proper, rather than in the more controlled environment of integration tests, so perhaps you need to re-think your approach.
If previous instances get collected, it's not a memory leak. The garbage collector doesn't always take the most recent items, and it's by design. If you try to second-guess it you'll likely run into problems.
In a real memory leak items will accumulate without ever being reclaimed. That's something best detected using the profiler.
Windows are not just managed by your code but also by some WPF classes like Application. Calling Collect does not guarantee or prove anything, the window does get collected eventually.
try with DispatcherPriority.ContextIdle
Dispatcher.CurrentDispatcher.Invoke( DispatcherPriority.ContextIdle, new System.Action(delegate { }));
Recently I noticed serious memory leak in my WPF project. If simplify the project, it has a login form and a main form. In main form there are 1 user control which is composed of about 30 user controls and 3 buttons, 1 user control which has 3 buttons and a Infragistics datagrid. I use background worker to query DB every 30 sec only for the datagrid.
After I logout of the main form using main form.closed and re-launch the login window, I noticed that every time there is 6-7MB increase measured by ANTS memory profiler 7. Even though I have unregistered event handlers, set variables to null and called GC.Collect(), memeory leak is still the same. My questions are:
1. Why close wpf window doesn't release the memory and resource? I can see many strings(most of them are from GUI) are still in memory after close window by ANTs profiler.
2. Do I need to unregister the events defined by resource event setter? Do I need to unregister the events declared in XAML?
3. From WPF memory leak, people said we should not use GC.Collect(), but I do see a little improvement. Shall we use it or not?
I have had a simillar problem while using WindowsFormsHost for PictureBox control.
The WPF window using WF PictureBox control could not be fully released and that's why i had a regular ~10mb increase everytime i re-opened the subwindow.
The problem was solved since i started nulling the WFH object on WPF window closing.
Just make sure You clear all the WF controls if You use such.
Break into the debugger and then type this into the Immediate window:
.load C:\Windows\Microsoft.NET\Framework\v2.0.50727\sos.dll
The path to sos.dll varies. The way to find out the correct path is to look for mscorwks.dll in the Modules pane. Wherever that is loaded from is the correct path for sos.dll.
Then type this:
System.GC.Collect()
That will ensure anything not reachable is collected. Then type this:
!DumpHeap -type <some-type-name>
This will show you a table of all existing instances, with addresses. You can find out what is keeping an instance alive like this:
!gcroot <some-address>
originally answered by Daniel
It depends. User controls in WPF do not inherently dispose, so you will have to override the functionality and allow it in your controls with:
http://msdn.microsoft.com/en-us/library/system.idisposable.dispose.aspx
But to your point, you will need to do a GC.Collect() at least once as SlimGG suggests.
In most cases, calling the garbage collector directly is considered bad practice because it is not calling it for your control specifically, but for all objects queued for disposal.
My control is being kept alive because of command it is bound to. How can I break this reference? This is causing a major memory leak in my application. The control is inside of a DataTemplate so I have no direct access to it.
Here is my ANTS memory profile:
How on earth do I break this connection?
Though I incorporated WeakEventListener, I discovered that my problem was with the control I was using to wrap up my images. I was hooking it up to DownloadProgress, ImageOpened, and ImageFailed events and never unhooked them. My thinking was that nothing else in my code was touching the BitmapImage objects so they would be garbage collected with the control. This, it sees, is not the case. The BitmapImage objects were referenced by a static member (and therefore a GC root) deep within Microsoft's code called "ManagedPeerTable.PeggedManagedPeersWithRefs". It was so deep that a Google search returned only five results for it. Now I suppose there will be six.