STrack lives in ultralytics.trackers.byte_tracker and the YAML loader is
ultralytics.utils.YAML; the basetrack/yaml_load names this module used are gone
in the pinned version. Caught by running the tracker tests against the real
dependency.
Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>
engine.py is the process-wide, thread-safe core the server is built on: one
YOLO instance behind a lock, thread-local matcher access, a classification pool
so detection is never starved, the stock catalog under its own lock, empty-slot
geometry normalized to a reference width (the detector's gap thresholds are
absolute pixels), and a small LRU of recent still images for later
classify/inspect calls. Detection output is normalized so every client sees the
same box shape.
tracking.py wraps ultralytics BYTETracker. The important part: ultralytics
mints track ids from a process-global counter and resets it when a tracker is
constructed, so with two live clients one client's ids would be re-issued while
the other still held cached labels. SessionTracker gives each tracker its own
counter and never touches the global one.
Measured defaults (bench_engine.py, M5): detection p50 26-29 ms on CPU vs
112 ms on MPS with byte-identical boxes, so device defaults to cpu; hybrid
classifies at ~51 ms/crop, 92 crops/s across 8 threads.
Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>
