From: Mike Bayer <mike_mp@zzzcomputing.com>
Date: Wed, 3 Feb 2021 21:56:58 +0000 (-0500)
Subject: fix gc related race in weakdict popitem
X-Git-Tag: rel_1_4_0b2~3
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=cf18bce4f179bb9a9038377afdfda24ac9e5db5b;p=thirdparty%2Fsqlalchemy%2Fsqlalchemy.git

fix gc related race in weakdict popitem

Change-Id: I88c19b6d3c97a714f7e4bf22812a23e095f9dcba
---

diff --git a/lib/sqlalchemy/orm/mapper.py b/lib/sqlalchemy/orm/mapper.py
index 16a2c64160..fe425301a0 100644
--- a/lib/sqlalchemy/orm/mapper.py
+++ b/lib/sqlalchemy/orm/mapper.py
@@ -3450,8 +3450,13 @@ def _dispose_registries(registries, cascade):
             )
 
         while reg._managers:
-            manager, _ = reg._managers.popitem()
-            reg._dispose_manager_and_mapper(manager)
+            try:
+                manager, _ = reg._managers.popitem()
+            except KeyError:
+                # guard against race between while and popitem
+                pass
+            else:
+                reg._dispose_manager_and_mapper(manager)
 
         reg._non_primary_mappers.clear()
         reg._dependents.clear()