Application stops responding upon calling SceneTree.Quit and never really quits

[HKunogi]

Tested versions

• Reproducible on v4.4.dev.mono.custom_build [74de05a] when using Run on Separate Thread for either or both of the physics (2D/3D)

System information

Windows 11 x64 and Ubuntu 24.04 ARM64

Issue description

When calling the SceneTree.Quit, instead of correctly quitting the application, instead, the application stops responding and does not actually quit, it stays lingering into an non-responsive state, may it be running from console only or with actual UI, as long as "Run on Separate Thread" is ticked on either of the physics (2D and/or 3D).

Steps to reproduce

• Enable Run on Separate Thread on project settings
• Simply call SceneTree.Quit

Minimal reproduction project (MRP)

mrp-quitbug.zip

[matheusmdx]

Bisecting points to commit 2d1dd41 from pr #96760 as the culprit

We had a similar issue #96931 with a pr to fix: #96959 but only talks about Rendering and Script server so just to make sure, @RandomShaper pr #96959 also works for this case?

[CedNaru]

That PR will work on anything that runs on the WorkerThreadPool, which includes the physic servers too.

[clayjohn]

This is indeed a duplicate of #96931 and will be fixed by #96959