Is this a memory leak in Xamarin Forms?

Question

I have run into a problem where it appears Page objects are not being Garbage Collected once they have been navigated away from. I have put together a very basic example of thi

Answer 1

I think what you are seeing is a side effect of async navigation, not memory leak. Instead of WeakReferences you might opt for a finalizer instead and create instances of MyPage (instead of ContentPage).

    public class MyPage: ContentPage
    {
        private static int count;

        public MyPage()
        {
            count++;
            Debug.WriteLine("Created total " + count);
        }
        ~MyPage()
        {
            count--;
            Debug.WriteLine("Finalizer, remaining " + count);
        }
    }

Next trick is to add a delayed GC.Collect() call, like:

    private static Page CreateWeakReferencedPage()
    {
        GC.Collect();
        var result = CreatePage();
        var ignore = DelayedGCAsync();
        return result;
    }

    private static async Task DelayedGCAsync()
    {
        await Task.Delay(2000);
        GC.Collect();
    }

You will note that instances get garbage collected within this delayed collection (output window). As per Xamarin GarbageCollector: I doubt that it has serious flaws. A minor bug here and there but not that huge. That said, dealing with garbage collections in Android is particularly tricky because there are two of those - Dalvik's and Xamarin's. But that is another story.