mojira.dev

KAIEDE

Assigned

No issues.

Reported

MC-240932 Hang on Entering Single Player World Cannot Reproduce

Comments

With 1.18 Pre-Release 4, I'm able to load the world again without performance tanking horribly using a 2GB heap. Even with a 32 chunk render distance.

It looks like this bug is/was a dupe of the heap exhaustion bug reported as fixed in pre-release 3?

I can confirm that increasing the maximum heap size does provide a workaround, but I'm definitely left wondering what is going on. 

With the larger max heap, I do notice that the memory used rises rapidly, gets collected, and then rises rapidly again. So every ~20-30 seconds it's going from 2.8GB to 5GB dropping back to 2.8GB and then rising back up to 5GB. I'm not even doing anything in the world, just standing still. That's quite a bit of heap churn compared to what I'm used to seeing with 1.17.1, that grows maybe a few hundred MB between collections, rather than multiple GB.

Unix-based systems report CPU usage where 100% is full load on one core. Over 500% means it was running full load on five cores, with work on a sixth.

It’s useful detail to describe that the process was stuck doing something with a lot of resources being used.

Couple notes I've seen:

  • I seem to hit this most often when it switches between day/night. Where the path tracing model would "reset", but just never come back up to proper light levels.

  • Workaround seems to be disabling and re-enabling RTX using ';' when encountering this bug. 

One more confirmation that things are improving. Whatever tended to destroy the CPU on fresh/young worlds on Ubuntu is now much closer in line with Windows. I also don’t have concrete metrics, but at the very least, comparing CPU usage of the VM process in each case are in the same margin of 5-10% CPU. That includes OS overhead in each case though, so it’s not a perfect comparison.

Our world isn’t quite heavy on Redstone, so I can’t speak to performance there. 

Windows VM (Bare) vs Ubuntu 20.04 VM (w/Docker)

CPU usage is markedly better on hosts like CubedHost as well.

This is probably one of the more annoying raytracing bugs for me. The constant flickering makes map walls harder to use, and could pose an accessibility issue.