How To Access Nodes Safely Inside Threads

Help Programming
,
1

Godot Version

4.3

Question

I am working on a project in which I am trying to implement multi-threading for the first time; And the main issue / roadblock I am running into now and have in the past is when trying to access nodes, every time and way I have tried gives a null reference, I have tried:

  1. %NodeName

  2. $Scene/…/NodeName

  3. $Scene.get_child(…).get_child(Node Index )

  4. get_tree().root.get_child(Scene Index ).get_child(…).get_child(Node Index )

All turn up null/nill at runtime, but only when on separate threads, all of these work on the main thread. How are you suppose to access/reference nodes on separate threads?
Thanks.

2

I unfortunately never worked with GDScript before, but I did run into a similar issue before when I was implementing a third party DLL into my game using C#.
When I was working on that, I discovered that I can do something like this:

Dispatcher.SynchronizationContext.Post(dispatchedDevice =>
{
    Array<Node> items = _itemsContainer.GetChildren();
    foreach (Node item in items)
    {
        _itemsContainer.RemoveChild(item);
        item.QueueFree();
    }
}, device);

I would assume the Dispatcher is available one way or another via GDScript as well, as it’s a Godot built-in. There seems to be very little documentation about this unfortunately, but I hope this sets you on the right path!

Hopefully someone with more GDScript knowledge will be able to help with something more specific.

3

Would that work for purposes other than deleting it? Also I would then need to reference the _itemsContainer which seems to move the issues upwards also.

4

Oh no, all the code you see inside that is custom logic I wrote. None of that is needed, obviously. What you need is the Dispatcher and the SynchronizationContext, which is supposed to be able to “interact” with other threads.

5

They may have other names for GDScript, but after googling I was unable to find info on both of those for searching ‘godot 4.3’ followed by there names. Could you send me a link to the docs for them so I can look into them further?

Thanks for the help!

6

After some research it turns out that GDScript handles this very differently. Take a look here: