Knowledge Base

Random Troubleshooting narrative

My new multiplayer Mineclonia survival world was suffering from severe lag. I wondered if it was related to the old CentOS 7-era hardware I run it on. Investigating showed some log entries about redstone events.

2026-03-05 16:00:12: ERROR[Server]: [mcl_redstone]: Maximum number of queued redstone events (65535) exceeded, deleting all of them.

This was a new world, with under 10 hours of gameplay, and we didn't have any redstone contraptions at all. I tried adjusting the incorrectly-labeled mcl_redstone_max_events (it was listed as mcl_redstone_event_max), which then let it actually count out all its redstone events, but then the errors occurred about max lag. So the server felt like it performed in the same bad way.

2026-03-05 16:00:10: WARNING[Server]: Server: Maximum lag peaked at 2.109 (steplen=0.05)

I found my old desktop computer, which was already running Rocky Linux 9, and set up podman, to conduct my first experiment with rootless podman. I've heard it supports compose compatibility, and I don't want to rewrite my docker-compose file into systemd units yet. I like the single file to control it all, rather than rewriting it in a different paradigm across 3 different service (unit) files.

I experimented with adjusting userns_mode and /run mounted from empty volumes. The game container fails because of s6 errors: It cannot chown various things. So I gave up on using rootless podman, and gave user luanti access to run sudo podman-compose. Then, the application would operate just fine.

So, with the game running, I connected and observed the same lagginess as before, even on the beefier host system. I investigated the game settings, and found an experimental flag I had turned on. By setting mcl_liquids_enable = false again, the game server operated normally.

Follow-up

Deep under the main play area, I found some large waterfalls. I could see how some performance-inhibiting waterfall calculations operated by the Mineclonia lua code could cause problems with that. Screenshot of gameplay

Screenshot of some waterfalls