Skip sync chunk load for MoveToBlock (fixes #6045)

[PaulBGD]

Any goal which extends this does a sync chunk/block lookup, which for
mobs close to the loaded chunk border will repeatedly lag the main
thread loading these.

This has been tested on production servers for a few weeks without any issues.

[PaulBGD]

Bump!

[Phoenix616]

Looks good to me. The only thing that might be an issue at some point is that Level#hasChunk(BlockPos) is deprecated but that shouldn't be hard to replace if it really gets removed at some point.

[jpenilla]

I tested this locally, adding a printout when !this.mob.level.hasChunkAt(mutableBlockPos) evaluated to true, and after flying around for quite a while and then letting the server idle for a while longer, I didn't see any printouts at all in console.

I'm not sure if maybe the issue here is an edge case, or if certain settings are needed to reproduce it? I was testing with everything completely default.

If someone can provide some test results different to mine, or if someone having the issue can enable sync load debug and show some evidence this is sync loading chunks, I'm happy to merge.

[PaulBGD]

Testing this out, I came to the same conclusion. I was wondering if the issue could be replicated by moving quickly, so that a chunk next to a fox wouldn't be loaded and it would sync load it. But I couldn't get that to reproduce either.

My best guess is with entities and chunks being decoupled in 1.17 that the issue this "fixed" occurred from an entity being ticked in a non-ticking chunk. Given that the MoveToBlockGoal always runs immediately on the 1st tick a mob is ticked for, it's likely that it's either this edge case or the moving fast/warping edge case with the nearby chunk not loaded yet.

This might still be a good fix knowing that these edge cases exist, although personally I think it'd be better to fix the core issue.

[electronicboy]

A good chunk of this stuff is generally solved by the ticketing system in general, the extra decoupling may also help with the tracking aspects of this too, generally there are some edge cases where an entity is ticked when we don't expect it to, e.g. entities nearing the "loaded" boundary is always iffy

[PaulBGD]

e.g. entities nearing the "loaded" boundary is always iffy

Especially on a busy server where chunks might be loading slower it's probably more of an issue. One potential "fix" for this which might be more natural is to just not tick MoveToBlockGoal on the initial mob tick, have it initially delayed by 10 ticks or something. I can imagine a lot of edge cases where looking up a 12x12 blocks around the mob on initial spawn might be a little sketchy.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[PaulBGD]

Probably an edge case, if I ever see another report of this I'll consider updating this then.