Chunksmith
An adaptive chunk pre-generator that paces generation to your server's disk - build large areas ahead of time without saturating I/O or freezing the server. A maintained fork of Chunky.
Chunksmith is a Minecraft chunk pre-generator that paces generation to keep your server healthy — it builds large areas ahead of time without saturating your disk or freezing the server.
New in 1.1.0 - Worldgen overreach diagnostic. When a worldgen feature or structure tries to setBlock outside its chunk - which vanilla refuses, normally spamming 100-200 near-identical log lines per occurrence - Chunksmith now collapses the whole burst into a single readable report naming the offending feature, the affected chunks, the Y range, and the block count, so you can identify and report the culprit mod instead of drowning in log noise. Full structured detail on Fabric/NeoForge (one version-portable binary across the entire 26.1-26.2 range); best-effort on Paper/Spigot/Folia.
A fork of Chunky by pop4959, licensed under GPL-3.0, maintained by Kishku7.
Why Chunksmith?
On slower hardware a heavy pre-gen can saturate disk I/O — leaving the server unresponsive to pause/stop, and on an empty server even sending it to sleep mid-run. Chunksmith focuses on generating safely under real-world conditions:
- Adaptive I/O throttle — generation concurrency is steered by live server tick-health (Fabric, NeoForge, and Paper): it backs off when the server starts to fall behind and ramps back up as it recovers, with a per-chunk latency backstop guarding against disk stalls on every platform.
- Run it 24/7 — even with players online. Because generation is paced by real-time server tick-health, Chunksmith automatically yields capacity to players the moment the server gets busy and reclaims it as load eases. No need to schedule pre-generation for off-hours or empty the server first — leave it running continuously and it stays out of players' way until the job is finished.
- Write-queue backpressure — watches the deferred region-write backlog and holds off dispatch when it grows too large, so generation can't outrun your disk;
pause/stopstay instant and a crash can't strand a huge write queue. (Fabric/NeoForge read the live IOWorker queue directly; on Paper the tick-health throttle + backstop apply.) - Stays awake during pre-gen — the server won't pause-when-empty out from under an unattended pre-gen.
- Conflict-safe — if the original Chunky is installed, Chunksmith disables it (Paper/Bukkit) or warns (Fabric/NeoForge).
- Drop-in migration — adopts your existing Chunky configuration on first run.
Real-world impact
Measured pre-generating a multi-million-chunk overworld on a spinning HDD:
| Stock Chunky | Chunksmith | |
|---|---|---|
| Disk during pre-gen | ~95-100% (pegged) | ~2-5% |
pause under load | seconds to minutes of lag | instant |
| Generation rate | choked by disk thrash | higher |
Same hardware, same world — Chunksmith generates faster while leaving the disk almost idle.
Commands
/cs (with /chunksmith as a full alias; the legacy /chunky still works, with a deprecation notice).
/cs start— pre-generate the selected area/cs pause— pause (resumable)/cs continue— resume a paused task/cs progress— rate / ETA / throttle status
Credits & license
Original Chunky by pop4959 and contributors. Chunksmith fork maintained by Kishku7. Licensed under GPL-3.0.
