Chunksmith

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/stop stay 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:

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.