Buff Mobs

[3.0.3] — buffmobs-3.0.3+mc1.21.11-fabric

🐛 Bug Fix — Compatibility with multithreaded mods

Fixed a crash when running BuffMobs alongside mods that process entities on multiple threads.

BuffMobs internally tracks which mobs have been initialized using HashSet and HashMap structures. These are not thread-safe — when another mod processes entities in parallel, multiple threads can read and write to these collections at the same time, causing a ConcurrentModificationException and crashing the server.

This patch replaces all affected collections in MobTickHandler with their thread-safe equivalents (ConcurrentHashMap / ConcurrentHashMap.newKeySet()). No behavior, configuration, or feature has been changed — only the underlying data structures.

✅ Confirmed fix

• Async — Fabric mod that parallelizes entity processing for better performance. Running Async + BuffMobs previously caused consistent crashes at startup or during play.

🔧 Likely fix for similar mods

Any mod that moves entity ticking or world ticking to worker threads may have triggered this same issue. This includes mods such as:

• Lithium (with certain async optimizations)
• FerriteCore (memory/threading optimizations)
• Other performance mods that offload entity processing

If you were experiencing random ConcurrentModificationException crashes with any of these in your modpack, this update should resolve it.

📋 Related

• Issue reported by the community: #12 — Crash with Async mod
• Special thanks to the humidityorder for identifying the root cause and providing the necessary details to track it down. 🙏

📦 Source & Issues: github.com/Khotyz/BuffMobs 🐛 Found another bug? Open an issue on GitHub!