Look for dict builtin in InstanceState cleanup

Added a check within the weakref cleanup for the :class:`.InstanceState` object to check for the presence of the ``dict`` builtin, in an effort to reduce error messages generated when these cleanups occur during interpreter shutdown. Pull request courtesy Romuald Brunet. Change-Id: If27b94d50a32767de8b4147c09fa423f71596004 Pull-request: #472
zzzeek · Sep 18, 2018 · 5059412 · 5059412
1 parent 67a2cd9
commit 5059412
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diff --git a/doc/build/changelog/unreleased_12/pr472.rst b/doc/build/changelog/unreleased_12/pr472.rst
@@ -0,0 +1,7 @@
+.. change::
+   :tags: bug, orm
+
+   Added a check within the weakref cleanup for the :class:`.InstanceState`
+   object to check for the presence of the ``dict`` builtin, in an effort to
+   reduce error messages generated when these cleanups occur during interpreter
+   shutdown.  Pull request courtesy Romuald Brunet.
diff --git a/lib/sqlalchemy/orm/state.py b/lib/sqlalchemy/orm/state.py
@@ -369,6 +369,13 @@ def _cleanup(self, ref):
         Will not work otherwise!
 
         """
+
+        # Python builtins become undefined during interpreter shutdown.
+        # Guard against exceptions during this phase, as the method cannot
+        # proceed in any case if builtins have been undefined.
+        if dict is None:
+            return
+
         instance_dict = self._instance_dict()
         if instance_dict is not None:
             instance_dict._fast_discard(self)