🔥 Sinborn Odyssey 2 — v1.3.9 (Alpha)

We tracked the server hang. It was Distant Horizons. Pack has 10 dimensions, DH spawned a chunk-gen queue + worker threads for each, deadlocked the main server thread mid-spawn-prep. Caught it on a thread-level diagnostic. v1.3.9 boots clean.

💀 What we killed

• 🌅 The 9% spawn-prep hang — Distant Horizons 2.4.5 was initializing DhServerLevel, BatchChunkGenerator, and WorldGenerationQueue for every dimension at boot (overworld, nether, end, plus 7 modded dims). The server's main thread froze during spawn-area generation right after dimension init. Players got "Server is still starting!" forever. Spark profiler couldn't even sample the main thread because it was so locked up. Killed by flagging DH client-only in the manifest.

🛡️ What changed

• 🌐 Distant Horizons 2.4.5 flagged server: unsupported. Server install no longer pulls DH. Clients still get DH — they generate LOD locally based on their own exploration. Multiplayer LOD-sync is reduced (server can't push pre-explored LODs), but everything else works exactly as before
• 📦 The pack now has 10-dimension friendly server boot. Spawn prep should complete in ~60 seconds instead of hanging forever

🧹 Under the hood

• 💾 Save-compatible — pure manifest env flag change
• 🔄 No content changes, no new mods, no balance shifts
• 🎯 Net effect for player: minor LOD detail loss in multiplayer (singleplayer unchanged)
• 🚀 Server boot time drops from infinity to ~60-90 seconds spawn prep

🔬 How we diagnosed it

1. Server stalled at 9% spawn-prep for 30+ minutes after upload
2. Spark async sampler started timing out → main thread dead-locked
3. Pulled log entries between 10% spawn-prep and first spark timeout
4. Found Distant Horizons spawning chunk-gen queues for 10 dimensions in the gap
5. Confirmed by deleting DH from server → boot succeeded
6. Locked it in for v1.3.9 with the proper env flag

If you were on v1.3.8

• Client players: update normally — your client still installs DH for visual LOD rendering. Distance you can see in singleplayer/exploration unchanged
• Server hosts: reinstall v1.3.9 — server install skips DH automatically. Spawn-prep finishes in 60 seconds for the first time today

What this means for the pack

The 10-dimension count was the breaking point — DH was designed for 1-3 dimension packs. This is the kind of latent issue that only surfaces on heavy modpacks like Sinborn. Now permanently dodged.

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