Disposing WPF User Control & Memory Management

Question

I have created a custom data grid control inherited from wpf data grid control in WPF.

So when user query the database several hundred records return with fifteen to twenty columns each.

I was believing that when i control the screen all the memory that is assigned to this screen and its grid should be reclaimed by GC. But this is not the case.

I was testing my application in Red Gate's Memory Profiler, it shows when i open the screen 30 mb of memory assigned to it.

But when i close this screen, application somehow still hold to that memory, when i was looking into the reason in ants memory profiler, it shows my screen's instance is still in memory because of my custom datagrid.

I've add unload event to my user control and detach all the event handlers that i've attached during the process.

What did i miss and what should i do?

Answer 1

You should not have to dispose a UserControl and you probably should not build an IDisposable UserControl. That's a design smell. The memory profiler can tell you why the application still holds to that memory and then you have to fix that bug.

Update:

To find out who is actually holding to that memory in ANTS you use the Instance Retention Graph feature. In .NET Memory Profiler (which I prefer over ANTS) it's called Root Path.