Chunk system patch was refactored to take advantage of
newer ConcurrentUtil's concurrent long hash table (which
fixes hash collisions caused by chaining fastutil's long hash
and CHM's hash) plus some other minor improvements.
The chunk system was also merged with Starlight, which mostly
provides a small improvement to ThreadedLevelLightEngine#checkBlock
as the scheduling was rewritten.
Patch documentation to come
Issues with the old system that are fixed now:
- World generation does not scale with cpu cores effectively.
- Relies on the main thread for scheduling and maintaining chunk state, dropping chunk load/generate rates at lower tps.
- Unreliable prioritisation of chunk gen/load calls that block the main thread.
- Shutdown logic is utterly unreliable, as it has to wait for all chunks to unload - is it guaranteed that the chunk system is in a state on shutdown that it can reliably do this? Watchdog shutdown also typically failed due to thread checks, which is now resolved.
- Saving of data is not unified (i.e can save chunk data without saving entity data, poses problems for desync if shutdown is really abnormal.
- Entities are not loaded with chunks. This caused quite a bit of headache for Chunk#getEntities API, but now the new chunk system loads entities with chunks so that they are ready whenever the chunk loads in. Effectively brings the behavior back to 1.16 era, but still storing entities in their own separate regionfiles.
The above list is not complete. The patch documentation will complete it.
New chunk system hard relies on starlight and dataconverter, and most importantly the new concurrent utilities in ConcurrentUtil.
Some of the old async chunk i/o interface (i.e the old file io thread reroutes _some_ calls to the new file io thread) is kept for plugin compat reasons. It will be removed in the next major version of minecraft.
The old legacy chunk system patches have been moved to the removed folder in case we need them again.
