WorkerThreadPool.add_group_task freeze when use all threads with high_priority

[Ohan17]

Tested versions

Reproducible in v4.4.1.stable.official [49a5bc7]

System information

Godot v4.4.1.stable - Windows 10 (build 19044) - Multi-window, 1 monitor - Vulkan (Forward+) - dedicated NVIDIA GeForce RTX 3050 Laptop GPU (NVIDIA; 32.0.15.7652) - 11th Gen Intel(R) Core(TM) i5-11400H @ 2.70GHz (12 threads)

Issue description

Calling WorkerThreadPool.add_group_task with tasks_needed = -1 and high_priority = true cause the app to freezes until all group tasks are finished at the same time. WorkerThreadPool should not block the main thread even when all its threads are busy.

extends Node2D

# Called when the node enters the scene tree for the first time.
func _ready() -> void:
	WorkerThreadPool.add_group_task(do, 100, -1, false) # doesn't freeze, call a few 'do' task a time
	#WorkerThreadPool.add_group_task(do, 100, -1, true) # freezes

func do(idx: int) -> void:
	for i in 10000000:
		pass
	print(idx)

Steps to reproduce

Run the small code snipet above.

Minimal reproduction project (MRP)

See above.

[AThousandShips]

Not sure this is a bug, you're occupying all threads with a relatively heavy operation, blocking engine functionality that need these threads, as far as I know engine internals don't have higher priority than these so things like processing the tree will be blocked by these

If that's the case this should simply be added as a note to the docs warning about this

[Ohan17]

This should be atleast added to the docs for warning yes. But imo, ideally engine internal operations should have higher priority or use different WorkerThreadPool than user tasks so that the main thread isn't stalled when all the threads are occupied, as this defeats the whole point of parallel processing

[AThousandShips]

How would that work? They use the same system, that would mean adding some extra system to denote even higher priority