[BUG] Media Element cannot be disconnected

[cagriy]

Is there an existing issue for this?

• I have searched the existing issues

Did you read the "Reporting a bug" section on Contributing file?

• I have read the "Reporting a bug" section on Contributing file: https://github.com/CommunityToolkit/Maui/blob/main/CONTRIBUTING.md#reporting-a-bug

Current Behavior

Upon exiting a page that has a MediaElement, although calling the DisconnectHandler as recommended, MediaElement does not get removed.

Expected Behavior

MediaElement should be garbage collected.

Steps To Reproduce

1. Open and run the solution from the reproduction repository
2. Click the button to go to the second page where the memory element lives
3. Click the back button to go to the main page
4. Check gcdump vie heapview and search for MediaElement

Link to public reproduction project repository

https://github.com/cagriy/MemoryLeak9

Environment

- .NET MAUI CommunityToolkit Media Element: 5.0.0
- OS: iOS 18.1
- .NET MAUI: 9.0.21

Anything else?

No response

[cagriy]

Hi @brminnick, I've upgraded Media Element to 5.0.0, but I still see the same problem. Is there anything else I need to be doing to make sure the media element is disconnected correctly?

The reproduction repo now includes a sample with the upgraded media element.

Sorry if I am missing something obvious.

[ne0rrmatrix]

Handler disconnect is done automatically by Maui now. If you want more info: https://learn.microsoft.com/en-us/dotnet/maui/whats-new/dotnet-9?view=net-maui-9.0. You can control it yourself if you set the handler disconnect policy.

Example:

 <toolkit:MediaElement
     x:Name="MediaElement"
     HandlerProperties.DisconnectPolicy="Manual"
     Source="https://commondatastorage.googleapis.com/gtv-videos-bucket/sample/BigBuckBunny.mp4"/>

The above code will let you control it manually. It is up to you if you want it to work this way now. By default it will work automatically in the background.

[ne0rrmatrix]

I can confirm that this is an issue with ios. I tested it for the last few hours and have found windows and android are fine buit IOS does show an error using the maui leak tool.

[MarcelStommel]

Am currently profiling memory leaks in an iPad app and found that my Media Elements aren't GC'ed either!
Looking through the code and my memory dump, it looks like this might me the culprit:

Maui/src/CommunityToolkit.Maui.MediaElement/Primitives/Metadata.macios.cs

Line 86 in 2e624ca

NowPlayingInfo.Artwork = new(boundsSize: new(320, 240), requestHandler: _ => GetImage(mediaElement.MetadataArtworkUrl));

Here requestHandler holds a reference to the Metadata class, by capturing this implicitly in the lambda.
Metadata then holds the MPNowPlayingInfo under the NowPlayingInfo Property
Which holds the MPMediaItemArtwork under the Artwork Property
Which in turn holds the requestHandler again, causing a reference cycle

The easy fix here would be making requestHandler a static lambda, so it doesn't capture this anymore, which I think is also the intention here, since GetImage is a static method anyways.

Also, this is currently just my theory, still have to test with the 'fix', if it even is one.

[pictos]

@MarcelStommel can you share this memory dump with us?

[MarcelStommel]

@pictos I don't think I can since it's an app from our customer, but I could reproduce it in small test app I wrote that just adds/removes a MediaElement from the page.

https://github.com/MarcelStommel/MediaLeak

After adding and removing the MediaElement it still resides in memory under iOS, even though it's handler got correctly disconnected and the element itself disposed.

I also wrote up a quick fix which basically involves using a proxy class instead of a lambda for the event handler. This way only the proxy class itself is captured.

public void SetMetadata(AVPlayerItem? playerItem, IMediaElement? mediaElement)
{
	...

	var proxy = new RequestHandlerProxy(mediaElement.MetadataArtworkUrl);

	...
	NowPlayingInfo.Artwork = new(boundsSize: new(320, 240), requestHandler: proxy.RequestHandler);
	...
}

class RequestHandlerProxy(string metadataArtworkUrl)
{
	public UIImage RequestHandler(CGSize size)
	{
		try
		{
			if (metadataArtworkUrl.StartsWith(Uri.UriSchemeHttp, StringComparison.OrdinalIgnoreCase))
			{
				return UIImage.LoadFromData(NSData.FromUrl(new NSUrl(metadataArtworkUrl))) ?? defaultUIImage;
			}
			return defaultUIImage;
		}
		catch
		{
			return defaultUIImage;
		}
	}
}

[pictos]

I can confirm, there's a memory leak when mediaElement is used like that. It doesn't happen if the page is removed from the navigation stack, in that scenario everything goes away