always set it (#7006)

python/ray/__init__.py

@@ -1,6 +1,5 @@
 import os
 import logging
-import multiprocessing
 from os.path import dirname
 import sys
 
@@ -14,7 +13,7 @@ if "pickle5" in sys.modules:
                       "requires a specific version of pickle5 (which is "
                       "packaged along with Ray).")
 
-if "OMP_NUM_THREADS" not in os.environ and multiprocessing.cpu_count() > 8:
+if "OMP_NUM_THREADS" not in os.environ:
     logger.warning("[ray] Forcing OMP_NUM_THREADS=1 to avoid performance "
                    "degradation with many workers (issue #6998). You can "
                    "override this by explicitly setting OMP_NUM_THREADS.")