a missing cursor.close() here caused a *huge* amount of weird locking issues with pypy,

what is strange is how it only occurred in some very specific places under very
particular conditions, perhaps it has to do with whether or not this cursor gets
gc'ed or not.

lib/sqlalchemy/engine/default.py

@@ -263,14 +263,17 @@ class DefaultDialect(interfaces.Dialect):
             cast_to = util.text_type
 
         cursor = connection.connection.cursor()
-        cursor.execute(
-            cast_to(
-                expression.select([
-                    expression.literal_column("'x'").label("some_label")
-                ]).compile(dialect=self)
+        try:
+            cursor.execute(
+                cast_to(
+                    expression.select([
+                        expression.literal_column("'x'").label("some_label")
+                    ]).compile(dialect=self)
+                )
             )
-        )
-        return isinstance(cursor.description[0][0], util.text_type)
+            return isinstance(cursor.description[0][0], util.text_type)
+        finally:
+            cursor.close()
 
     def type_descriptor(self, typeobj):
         """Provide a database-specific :class:`.TypeEngine` object, given