Lesson 2: Keeping training stable, and debugging it when not
27 min read·
Module 4 · Lesson 2 · About 50 minutes · Needs: lesson 1 (a training step, AdamW), L2 penalties (Module 3 lesson 1), and the Kestrel data (course-guide/06).
The situation
Week 4 at Kestrel, day three. The lesson 1 network trained in four epochs. Given longer runs, more layers or September's data, networks fail in quieter ways: they memorise, they stall, they blow up on one bad batch. Adaeze's rule for ADR-002: "No network goes in front of the trees until you can tell me why each run behaved as it did."
The running example is a wide network trained on a small sample, 3,000 training parcels, so every failure shows in seconds. KP0104204, the late Dartford parcel from lesson 1, is scored along the way.