I’ve been looking into garbage collection and stumbled upon different types of GC handles. I get the basic idea behind weak, normal, and refcounted handles. But I’m confused about pinned handles.
What’s the main reason for using pinned GC handles? Is it just to keep objects from moving around in memory, or is there more to it?
Also, I noticed something odd in my WPF app. I have a datagrid that uses a DiffCell array. When I close the window containing the datagrid, I see a pinned GC handle pointing to an empty DiffCell array through an object. I set the ItemsSource to null before closing, and I don’t use any unsafe code, so I’m really curious about why this array is getting pinned.
I would appreciate any insights on this issue. Thanks for your help!
pinned handles r useful for interop stuff, keepin objects in place when talkin to unmanaged code. for ur wpf issue, could be some internal caching goin on. try using a memory profiler to see whats holdin onto that array. sometimes frameworks do weird optimizations that can cause unexpected behavior like this
I’ve dealt with pinned GC handles quite a bit in my work, and they’re definitely a bit tricky to wrap your head around at first. The main purpose is indeed to prevent objects from being moved around by the garbage collector. This is crucial when you’re passing memory addresses to unmanaged code, which is common in interop scenarios.
As for your WPF issue, that’s an interesting one. I’ve seen similar behavior before, and it’s often related to how WPF handles data binding and object lifetime. Even though you’re setting ItemsSource to null, there might be some internal caching or delayed cleanup happening. It’s also possible that some event handler or binding is still holding onto a reference.
Have you tried using a memory profiler to dig deeper? Tools like dotMemory or ANTS Memory Profiler can be really helpful for tracking down these kinds of issues. They can show you the full object graph and help identify what’s keeping your array from being collected.
In my experience, these kinds of unexpected pinned handles often point to optimization attempts in the framework itself. It might be worth checking if there are any known issues or performance tweaks related to DataGrid in your WPF version.
Pinned GC handles serve a crucial purpose in certain scenarios, particularly when interfacing with unmanaged code. They ensure that objects remain at a fixed memory location, which is essential when passing object references to native APIs or when performing operations that require memory stability.
Regarding your WPF DataGrid issue, it’s not uncommon to encounter unexpected behavior with complex UI components. The pinned handle you’re observing could be a result of internal optimizations within the WPF framework. It’s possible that the DataGrid is maintaining a cached reference to improve performance on subsequent data loads.
To troubleshoot this, you might consider implementing IDisposable on your window class and manually clearing any references in the Dispose method. Additionally, running your application through a memory profiler could provide valuable insights into object lifetimes and help identify any potential memory leaks or unexpected references.