Error in noise_generator.gd when using ThreadedChunkLoader2D

[Ronzan]

Hello

Not sure if I'm doing something wrong, but I get following error:

E 0:00:00:0801   noise_generator.gd:72 @ generate_chunk(): Caller thread can't call this function in this node (/root/Main/NoiseGenerator). Use call_deferred() or call_thread_group() instead.
  <C++ Error>    Condition "!is_accessible_from_caller_thread()" is true. Returning: (ERR_INVALID_PARAMETER)
  <C++ Source>   scene/main/node.cpp:3630 @ emit_signalp()
  <Stack Trace>  noise_generator.gd:72 @ generate_chunk()
                 chunk_loader_2d.gd:86 @ _update_loading()
                 threaded_chunk_loader_2d.gd:26 @ <anonymous lambda>()

The setup is working, generating chunks as the player moves around - it lags a lot when chunks are generated though.
The setup looks like this:

I've tried to search a bit and found a few places that mentions signals not being thread-safe - but I really don't know since this is my first Godot test project :)
I can make a full repro if needed, just thought I would check here to see if I've done something obvious wrong.

/Ronzan

[cullumi]

Hi there @Ronzan!

This is indeed because signals aren't thread-safe. Ideally there will be a second pass (by me, most likely) on a few of the generators to make sure such things are thread-safe out of the box.

For now, wrap those signals with a lambda, then call_deferred them, similar to in the Heightmap generators:

(func(): chunk_updated.emit(chunk_position)).call_deferred() # deferred for threadability
(func(): chunk_generation_finished.emit(chunk_position)).call_deferred() # deferred for threadability

It's not exactly clean looking, persay, but it is the best way to fix this issue based on what I've read in Godot's docs.

[Ronzan]

Hi @cullumi
That removed those errors thank you :)
Btw, do I need to configure or do anything else to get the whole threaded chunkloading/generation/rendering system running smooth? While it does feel a bit smoother than non-threaded, I still have noticeable lag spike when new chunks/tiles are generated. Feels like I'm missing something :)

[cullumi]

Happy to help! :D

After doing some stress-testing, it seems that a bunch of deferred calls to TileMap.set_cell() and TileMap.erase_cell() in TilemapGaeaRenderer's _draw_area method were being batched together and run all at the same time.

The solution? Replace those deferred calls with thread_safe calls. This should help because now tile changes will be guaranteed to be paced out as they become ready; should smooth things out a bit.

In TilemapGaeaRenderer, try changing the following lines from:

tile_map.erase_cell.call_deferred( l, Vector2i(x, y))
(...)
tile_map.set_cell.call_deferred(
    tile_info.tilemap_layer, tile, tile_info.source_id,
    tile_info.atlas_coord, tile_info.alternative_tile
)

to:

tile_map.call_thread_safe("erase_cell", l, Vector2i(x, y))
(...)
tile_map.call_thread_safe("set_cell",
    tile_info.tilemap_layer, tile, tile_info.source_id,
    tile_info.atlas_coord, tile_info.alternative_tile
)

Hopefully that helps with the lag spikes. (I'll likely be making PR with these changes tomorrow if someone else doesn't beat me to the punch; it's late and I gotta work tomorrow morning lol)

[Ronzan]

Thanks again @cullumi
It did improve a bit. If I disable "Erase Empty Tiles" on the ThreadedTilemapGaeaRender node the spikes are gone in the y direction (moving up and down)! I still have noticeable spikes moving left and right...
I think I'm running all nodes with default values (except for the noise gen tiles data).
I'm not missing something basic, like setting he process thread group on the node, running in debug mode or something?
I am a complete Godot noob after all :)

Running the profiler, it looks like it is renderers and the chunkloader causing the spikes:

Should I make an isolated project and try and reproduce? or record a clip?
Thanks again for you work and assistance - much appreciated :)

[BenjaTK]

Fixed in #127