Added/Updated tests\bugs\gh_7863_test.py: Resultset of cursor that executes using instance of selectable PreparedStatement must be stored in some variable in order to have ability close it EXPLICITLY, before PS will be freed. Otherwise access violation can raises when Python runs garbage collection.

tests/bugs/gh_7863_test.py

@@ -6,6 +6,13 @@ ISSUE:       7863
 TITLE:       Non-correlated sub-query is evaluated multiple times if it is based on a VIEW rathe than on appropriate derived table.
 DESCRIPTION:
 NOTES:
+    [18.01.2025] pzotov
+    Resultset of cursor that executes using instance of selectable PreparedStatement must be stored
+    in some variable in order to have ability close it EXPLICITLY (before PS will be freed).
+    Otherwise access violation raises during Python GC and pytest hangs at final point (does not return control to OS).
+    This occurs at least for: Python 3.11.2 / pytest: 7.4.4 / firebird.driver: 1.10.6 / Firebird.Qa: 0.19.3
+    The reason of that was explained by Vlad, 26.10.24 17:42 ("oddities when use instances of selective statements").
+   
     Confirmed bug on 6.0.0.222
     Checked on 6.0.0.223, 5.0.1.1322.
 """
@@ -58,12 +65,21 @@ def test_1(act: Action, capsys):
         result_map = {}
 
         for qry_txt in q_map.keys():
-            with cur.prepare(qry_txt) as ps:
+            ps, rs = None, None
+            try:
+                ps = cur.prepare(qry_txt)
                 q_map[qry_txt] = ps.detailed_plan
                 for tab_nm,tab_id in t_map.items():
                     tabstat1 = [ p for p in con.info.get_table_access_stats() if p.table_id == tab_id ]
-                    cur.execute(qry_txt)
-                    for r in cur:
+            
+                    # ::: NB ::: 'ps' returns data, i.e. this is SELECTABLE expression.
+                    # We have to store result of cur.execute(<psInstance>) in order to
+                    # close it explicitly.
+                    # Otherwise AV can occur during Python garbage collection and this
+                    # causes pytest to hang on its final point.
+                    # Explained by hvlad, email 26.10.24 17:42
+                    rs = cur.execute(ps)
+                    for r in rs:
                         pass
                     tabstat2 = [ p for p in con.info.get_table_access_stats() if p.table_id == tab_id ]
 
@@ -77,6 +93,14 @@ def test_1(act: Action, capsys):
                         seq -= (tabstat1[0].sequential if tabstat1[0].sequential else 0)
                         idx -= (tabstat1[0].indexed if tabstat1[0].indexed else 0)
                         result_map[qry_txt, tab_nm] = (seq, idx)
+            except DatabaseError as e:
+                print( e.__str__() )
+                print(e.gds_codes)
+            finally:
+                if rs:
+                    rs.close() # <<< EXPLICITLY CLOSING CURSOR RESULTS
+                if ps:
+                    ps.free()
 
         for k,v in result_map.items():
             print(k[0]) # query