From 04fbb9e63c098dd2de40b545eed210dfd93893ce Mon Sep 17 00:00:00 2001
From: Mike Bayer <mike_mp@zzzcomputing.com>
Date: Fri, 27 Dec 2019 15:02:31 -0500
Subject: Test for short term reference cycles and resolve as many as possible

Added test support and repaired a wide variety of unnecessary reference
cycles created for short-lived objects, mostly in the area of ORM queries.

Fixes: #5056
Change-Id: Ifd93856eba550483f95f9ae63d49f36ab068b85a
---
 lib/sqlalchemy/sql/traversals.py | 2 ++
 1 file changed, 2 insertions(+)

(limited to 'lib/sqlalchemy/sql/traversals.py')

diff --git a/lib/sqlalchemy/sql/traversals.py b/lib/sqlalchemy/sql/traversals.py
index 84a5623d3..68a3a0749 100644
--- a/lib/sqlalchemy/sql/traversals.py
+++ b/lib/sqlalchemy/sql/traversals.py
@@ -29,6 +29,8 @@ def compare(obj1, obj2, **kw):
 class HasCacheKey(object):
     _cache_key_traversal = NO_CACHE
 
+    __slots__ = ()
+
     def _gen_cache_key(self, anon_map, bindparams):
         """return an optional cache key.
 
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