Apply suggestions from code review

Co-authored-by: Olivier Grisel <olivier.grisel@ensta.org>

cloudpickle/cloudpickle.py

@@ -1143,7 +1143,9 @@ def _class_setstate(obj, state):
         else:
             # Note: attribute names are automatically interned in cpython. This means that to get
             # determinist pickling in subprocess, we need to make sure that the dynamic function names
-            # are also interned.
+            # are also interned since the Pickler's memoizer relies on physical object
+            # identity to break cycles in the reference graph of the object being
+            # serialized.
             # https://github.com/python/cpython/blob/main/Objects/object.c#L1060
             setattr(obj, attrname, attr)
     if registry is not None:

tests/testutils.py

@@ -218,8 +218,10 @@ def assert_run_python_script(source_code, timeout=TIMEOUT):
 def check_determinist_pickle(a, b):
     """Check that two pickle output are the same.
 
-    If it is not the case, print the diff between the disaembled pickle.
-    This helper is useful to investigate non-determinist pickle.
+    If it is not the case, print the diff between the disassembled pickle
+    payloads.
+
+    This helper is useful to investigate non-deterministic pickling.
     """
     if a != b:
         with io.StringIO() as out: