Using PCG, having a graph and component setup to do Hierarchal Generation, if the PCG graph has a Grid Size node present(not necessarily hooked up) while using the PCGWorldPartitionBuilder to generate the graph from command line will give a deadlock error if used in conjunction with Iterative Cell Loading either on a PCG Builder Settings asset config or via the commandlet args.
The error is:
LogPCG: Error: PCG Graph executor error: tasks are in a deadlocked state. Will drop all tasks.
Not using Iterative Cell Loading seems to solve the issue, but this is not really an option for large scale worlds as the memory needed to generate a full map is too high.
Is it expected that these two features cannot work in unison or is there another recommended path for doing headless generations for PCG that works with a partition based generation?
I just tried using a builder with Iterative Cell Loading on a map containing a Partitioned PCG Volume with a HiGen graph (25600, 12800, 6400 grids) and didn’t get any issue with deadlocked state.
Do you have a project / map to share that can help us repro this issue?
Edit: I want to add, I have found issues with some PCGPartitionActors not getting generated properly on lower grid sizes. Fixes will be in 5.6 but if you ever need those and can integrate them from UE5 Main then I will update here with the CL number once it is submitted
Thanks for the answer, I have it repo’ing in two projects, our inhouse project but also a vanilla 5.5.3 unreal project based off the third person template, which I have stripped down and attached. We have also verified it is not machine based as other machines also hit the same deadlock.
Here is also the command line I used to trigger the generation:
"C:\Program Files\Epic Games\UE_5.5\Engine\Binaries\Win64\UnrealEditor.exe" "PATH_TO_PROJECT" "/Game/LargeWorldLandscapePatch" -Unattended -run=WorldPartitionBuilderCommandlet -AllowCommandletRendering -builder=PCGWorldPartitionBuilderThe project does have the LandscapePatches plugin installed and did use it in the level, but these were removed to see if they were contributing to the deadlock, but it seems to still repo with them removed.
Another small note is I tried to make a completely new blank project with a similar setup, but only with PCG on a landscape with the grid setup, and it did not reproduce there and I could not figure out what might have been the difference(aside from the landscape patch plugin being installed and the project having been upgraded from earlier versions of Unreal)
It turns out the issue is the combination of using Hierarchical Gen which introduces dependencies between components and the “One Component at a time” flag on the Builder Settings.
I will fix this but in the meantime you can uncheck that setting in the Builder Settings and the Builder should complete succesfully.