Merge "Explicitly use a session for DB version check"

ironic/db/sqlalchemy/api.py

@@ -1798,7 +1798,8 @@ class Connection(api.Connection):
             #             compatible with its (old) DB representation.
             # NOTE(rloo): .notin_ does not handle null:
             # http://docs.sqlalchemy.org/en/latest/core/sqlelement.html#sqlalchemy.sql.operators.ColumnOperators.notin_
-            query = model_query(model.version).filter(
+            with _session_for_read() as session:
+                query = session.query(model.version).filter(
                     sql.or_(model.version == sql.null(),
                             model.version.notin_(supported_versions)))
                 if query.count():

releasenotes/notes/remove-model-query-from-upgrade-af227b6c8a5d654a.yaml

@@ -0,0 +1,9 @@
+---
+fixes:
+  - |
+    Fixes an issue where the database upgrade can hang on Python 3.10.
+    This was because open transactions could become orphaned awaiting
+    the Python runtime to clean up their memory references due to the
+    way the overall database query was being intiiated to pre-flight
+    check the upgrade. We have structurally changed the behavior
+    to remedy this case.