Respect ENV value for `OMP_NUM_THREADS` if set (#16751)

Co-authored-by: UltralyticsAssistant <web@ultralytics.com>
Co-authored-by: Glenn Jocher <glenn.jocher@ultralytics.com>

ultralytics/__init__.py

@@ -4,8 +4,9 @@ __version__ = "8.3.7"
 
 import os
 
-# Set ENV Variables (place before imports)
-os.environ["OMP_NUM_THREADS"] = "1"  # reduce CPU utilization during training
+# Set ENV variables (place before imports)
+if not os.environ.get("OMP_NUM_THREADS"):
+    os.environ["OMP_NUM_THREADS"] = "1"  # default for reduced CPU utilization during training
 
 from ultralytics.data.explorer.explorer import Explorer
 from ultralytics.models import NAS, RTDETR, SAM, YOLO, FastSAM, YOLOWorld