FrameData.Bytes() alloc memory and never free

[JoeyLee0201]

Hi， I recently implemented a progress via learning demuxing_decoding

I wrote a function to handle video frame like this:

func (vl *VideoLoader) handleVideoFrame(ctx context.Context, frame *astiav.Frame) {
	bytes, err := frame.Data().Bytes(1)
	if err != nil {
		return
	}

	vdieoFrame := utils.BuildVideoFrame(frame.Width(), frame.Height(), bytes, nil)

	// do something
	return
}

I make sure to have called frame.Unref() and frame.Free(), and I notice the heap about in_use_space is released correctly, but there is still memory allocated which is releated to FrameData in alloc_space, even after for a long time later.
Do you have any idea about this issue?

Thank you !

380: 1182924800 [1514687: 4715160043520] @ 0x2afe168 0x2af9d02 0x2bb266a 0x2bb17bc 0x2bb13b3 0x2bb0d4a 0x63a101
#	0x2afe167	github.com/asticode/go-astiav.(*frameDataFrame).bytes+0x407 
 /opt/tiger/compile_path/pkg/mod/github.com/asticode/[email protected]/frame_data.go:284
#	0x2af9d01	github.com/asticode/go-astiav.(*FrameData).Bytes+0x81	 
 /opt/tiger/compile_path/pkg/mod/github.com/asticode/[email protected]/frame_data.go:39
#	0x2bb2669	avloader.(*VideoLoader).handleVideoFrame+0x1c9	/avloader/loader.go:368
#	0x2bb17bb	avloader.(*VideoLoader).loadFrame.func2.1+0x35b	/avloader/loader.go:289
#	0x2bb13b2	avloader.(*VideoLoader).loadFrame.func2+0x5f2	/avloader/loader.go:326
#	0x2bb0d49	avloader.(*VideoLoader).loadFrame+0x4a9		/avloader/loader.go:331

[asticode]

I've also experienced this behavior and here were my conclusions:

• as long as the in_use_space is behaving properly, you're good
• the alloc_space not freeing memory space back to the OS hugely depends on the allocator you're using. I had widely different behaviors between different allocators I tested (e.g. tcmalloc, jemalloc, etc.)

[JoeyLee0201]

Thanks a lot! I'm a novice in this area. Could you provide some examples for reference on how to configure allocators, and which one would you recommend for better performance?

[asticode]

In order to use a different allocator than the default one, you need to build ffmpeg with the --custom-allocator=<your allocator> flag (e.g. --custom-allocator=jemalloc) during the configure step. In that case astiav and ffmpeg will use this allocator instead.

It's hard to recommend an allocator since there isn't one that has better performance overall than the others, but each one has advantages in specific situations. I'd recommend doing a google/stackoverflow search to learn the differences between tcmalloc and jemalloc if you want to use an allocator different than the default one 👍 But there may be other allocators out there that would fit better your needs.