Android DataBinding is leaking Memory

According to fragment lifecycle, onDestroyView() was called, but fragment is not fully destroyed - so onDestroy() is not called. In that case, if you don't reset binding property by hand, it references view tree (it's some kind of leak).

But if I need to do this then what is the point of binding.lifecycleOwner = viewLifecycleOwner then?

If you supply LifecycleOwner to binding object, it allows to observe all LiveData objects inside generated binding class. But it can't know about external references on binding instance outside (from any other classes of your project) - that's why it can't automatically reset them.

Here is the recommended way from google docs to initialize and clear the binding in Fragments:

Kotlin:

private var _binding: ResultProfileBinding? = null
// This property is only valid between onCreateView and
// onDestroyView.
private val binding get() = _binding!!

override fun onCreateView(
    inflater: LayoutInflater,
    container: ViewGroup?,
    savedInstanceState: Bundle?
): View? {
    _binding = ResultProfileBinding.inflate(inflater, container, false)
    val view = binding.root
    return view
}

override fun onDestroyView() {
    super.onDestroyView()
    _binding = null
}

Java:

private ResultProfileBinding binding;

@Override
public View onCreateView (LayoutInflater inflater, 
                          ViewGroup container, 
                          Bundle savedInstanceState) {
    binding = ResultProfileBinding.inflate(inflater, container, false);
    View view = binding.getRoot();
    return view;
}

@Override
public void onDestroyView() {
    super.onDestroyView();
    binding = null;
}

Also, here is a medium blog post to read to get rid of binding memory leak with Property Delegate.

Just call binding.unbind() in onDestroyView() method.