Should I ever manually force garbage collection in my WPF app?

Question

I've just been sorting out some memory leaks in my WPF application. To do so, I used the CLR profiler, as well as watching process statistics in Windows Task Manager. My basic test was to make sure that when a certain window was closed, it didn't still hang around in memory.

I'm slightly new to windows development, and at first I was getting confused because in a simple test application, it seemed as if no matter what, my windows were always staying in memory after being closed. But I eventually worked out that this did not mean there was a memory leak, but just simply that they hadn't been garbage collected yet. So I had to create a button in my main window hooked up to an event handler that contained code to manually force garbage collection. By manually garbage collecting, I could then complete my memory leak tests, and I got it all sorted.

But it got me thinking - is there ever a need to manually force garbage collection?

It pains me to watch my application's memory consumption go up and up as I open and close windows. Of course, eventually, garbage collection automatically runs and it all gets sorted out. But it almost seems like a good idea to manually garbage collect after these heavy windows get closed. But is there any point? I get the feeling that testing aside, we are not supposed to force garbage collection - just let the system sort it out.

Thoughts appreciated.

Answer 1

Thanks for the feedback guys. I'll go along with your advice and let the system take of care of what the system was designed to take care of!

I actually have since found a good answer to my question in a book I have on the .NET framework. It says:

The whole purpose of the .NET garbage collector is to manage memory on our behalf. However, in some very rare circumstances, it may be beneficial to programmatically force a garbage collection using GC.Collect(). Specifically:

• When your application is about to enter into a block of code that you don't want interrupted by a possible garbage collection.
• When your application has just finished allocating an extremely large number of objects and you wish to remove as much of the acquired memory as soon as possible.

Answer 2

It is a good practice never force garbage collection manually, in any .NET application. GC is supposed to be smartest than us ( and actually it is smart ). Unfortunately if there is memory leak, even calling forcibly the GC does not help.

Answer 3

I agree with you on both sides of your point :-). I generally take the approach that the people who wrote the .NET runtime are smarter than I am and have a better understanding of garbage collection than I do, so I leave it alone.

I have seen a few instances where people thought they were doing good by forcing garbage collection, but there was never any hard evidence that it helped.