🌟 Summary v8.4.126 makes restricted checkpoint loading safer and up to 40% faster in concurrent environments, while simplifying RLE loss calculations and preserving backward compatibility. 📊 Key Changes 🔒 Thread-safe restricted checkpoint loading Fixed a race condition when multiple threads loaded PyTorch checkpoints with restricted loading enabled. The shared allow-list is now registered for the process lifetime instead of being temporarily removed when one thread finishes. Added a regression test covering 32 concurrent restricted loads. ⚡ Faster restricted model loading Only checkpoint globals actually referenced by a file are registered, rather than rebuilding a large allow-list for every load. This reduces restricted-loading overhead by approximately 40% in affected cases. 🛡️ Improved compatibility with secure loading Restricted loading now requires PyTorch functionality available from version 2.6 onward; older versions continue to fall back to standard loading behavior. Normal, unrestricted loading remains unchanged. Official YOLO26 checkpoints, including YOLO26x, are protected from failures caused by concurrent loading. 🧠 Simplified RLE prior calculation Replaced the runtime multivariate distribution object with a simpler closed-form implementation. Retained existing checkpoint buffers so models saved before v8.4.126 can still resume correctly. Improved numerical behavior under mixed-precision training. 🏷️ Version update Updated the Ultralytics package version from 8.4.125 to 8.4.126. 🎯 Purpose & Impact ✅ More reliable production inference: Multi-threaded services and Platform CPU workers can load models concurrently without intermittent checkpoint errors. 🚀 Reduced startup and loading time: Restricted checkpoint loading performs less unnecessary work, benefiting applications that frequently load models. 🔐 Maintained security benefits: Safe loading continues to limit checkpoint reconstruction to known, approved classes. 🔄 Backward compatible: Existing unrestricted workflows and older saved model checkpoints continue to work as before. 📉 Cleaner internal implementation: The RLE change removes unnecessary distribution-object overhead without changing the intended loss behavior. What's Changed Make restricted checkpoint loading thread-safe and 40% faster, simplify RLE prior by @pderrenger in https://github.com/ultralytics/ultralytics/pull/25885 Full Changelog: https://github.com/ultralytics/ultralytics/compare/v8.4.125...v8.4.126