chore: import upstream snapshot with attribution

python/ray/cloudpickle/compat.py

@@ -0,0 +1,19 @@
+import logging
+import os
+
+logger = logging.getLogger(__name__)
+
+RAY_PICKLE_VERBOSE_DEBUG = os.environ.get("RAY_PICKLE_VERBOSE_DEBUG")
+verbose_level = int(RAY_PICKLE_VERBOSE_DEBUG) if RAY_PICKLE_VERBOSE_DEBUG else 0
+
+if verbose_level > 1:
+    logger.warning(
+        "Environmental variable RAY_PICKLE_VERBOSE_DEBUG is set to "
+        f"'{verbose_level}', this enabled python-based serialization backend "
+        f"instead of C-Pickle. Serialization would be very slow."
+    )
+    from ray.cloudpickle import py_pickle as pickle
+    from ray.cloudpickle.py_pickle import Pickler
+else:
+    import pickle  # noqa: F401
+    from _pickle import Pickler  # noqa: F401