Question

I have read a lot about this topic, and still I don’t have the clear path how to proceed. Can anyone point to some resource (or explain) that shows in detailed step how to find the reason why some objects dctor is not called.

basically my logic for testing leak is this (WPF application):

1. create some View/ViewModel
2. close the View
3. call GC.Collect()

After a few seconds a dctor on ViewModel class is normally called, but on my application is never called. I would like to know which object is holding a reference to it at that time, since in my opinion it is the way to find the cause of memory leak.

This classes do not user any unmanaged resources, and do not have IDisposable implemented, which means there is no SupressFinalize call to prevent desctructor execution.

Edit: ViewModel is retrieved through a Static property on ViewModelLocator, and is added List. This is required by TabControl, which needs collection of view models to bind to. View and ViewModel are connected through DataTemplate.

Answer 1

First, search for non-unsubscribed event handlers and static references pointing to your ViewModel, even indirectly. Since you’re in a WPF application, also ensure that you don’t use DependencyPropertyDescriptor.AddValueChanged which is known to cause leaks by using static references.

If you can’t find anything manually, use the awesome (this is my opinion, I’m in no way affiliated with them) SciTech .NET Memory Profiler. You can see for every object all the references it holds and which other objects are holding a reference to it, in a nice graph
view. It also warns you for common memory problems.

EDIT:

ViewModel is retrieved through a Static property on ViewModelLocator

Search no longer, you have your leak. Static references prevent objects from being garbage collected. Remove the static reference or wrap it in a WeakReference.