GodotSharp deadlock in RemoveScriptBridge / CreateScriptBridgeForType on scene transition

[DavidVonDerau]

Tested versions

• Occurs in: v4.2.mono.official [46dc277]

System information

Godot v4.2.stable.mono - Windows 10.0.19045 - Vulkan (Forward+) - dedicated NVIDIA GeForce RTX 3080 (NVIDIA; 31.0.15.3667) - AMD Ryzen 7 5800X 8-Core Processor (16 Threads)

Issue description

I believe this is a race condition between GodotObject Dispose and load_threaded_request but I'm not certain.

Very rarely on a scene transition where a new scene with C# scripts is loaded in the background using load_threaded_request, while simultaneously 1 or more Nodes with C# scripts has been QueueFree()'d from the SceneTree, the project will deadlock.

A GodotObject calling Dispose (one of the nodes that had QueueFree called) will block on removing the attached C# script, while the new scene that is being loaded in the background will block on creating a new C# script.

The call stack for all threads looks like:

Steps to reproduce

The following is a hypothesis because I'm having trouble narrowing this down.
I'm mostly working off the stack trace above and looking at what my code is doing during the scene transition, but it's possible that the actual issue is caused by something entirely unrelated.

1. Create a "scene container" master scene.
2. Create a function to transition scenes -- QueueFree() the current scene node, load_threaded_request the new scene, and then Instantiate + AddChild when the threaded request is complete.
3. Using two scenes that both have Nodes with C# scripts attached, transition repeatedly between the scenes.
4. Rarely the entire application will permanently deadlock during the transition on the stack trace shown above.

Minimal reproduction project (MRP)

N/A (I haven't figured out the MRP steps yet)

[d6e]

This might be the same issue as this #87405

which apparently should be fixed in Godot 4.2.2: #87669

[akien-mga]

@DavidVonDerau Could you confirm whether 4.2.2-rc2 fixes the issue?

[AThousandShips]

Closing due to lack of response, if you provide the requested information this can be reopened