Added/Updated tests\bugs\gh_8265_test.py: CRITICAL ISSUE. 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. See notes.

tests/bugs/gh_8265_test.py

@@ -17,6 +17,38 @@ NOTES:
     
     Confirmed problem on 5.0.2.1516-fe6ba50 (23.09.2024).
     Checked on 5.0.2.1516-92316F0 (25.09.2024).
+
+    [15.01.2025] pzotov
+
+    ### CRITICAL ISSUE ### PROBABLY MUST BE APPLIED TO ALL TESTS WITH SIMILAR BEHAVOUR ###
+
+    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.
+    This occurs at least for: Python 3.11.2 / pytest: 7.4.4 / firebird.driver: 1.10.6 / Firebird.Qa: 0.19.3
+
+    Example of broken pytest log when AV occurs:
+    ==========
+        tests/bugs/gh_8265_test.py::test_1 Windows fatal exception: access violation
+
+        Current thread 0x0000385c (most recent call first):
+          Garbage-collecting
+          File "C:/Python3x/Lib/site-packages/firebird/driver/interfaces.py", line 831 in free
+          File "C:/Python3x/Lib/site-packages/firebird/driver/core.py", line 2736 in free
+          ...
+          File "C:/Python3x/Scripts/pytest.exe/__main__.py", line 7 in <module>
+          File "<frozen runpy>", line 88 in _run_code
+          File "<frozen runpy>", line 198 in _run_module_as_main
+        PASSED                           [1773/2565]
+    ==========
+    The reason of that was explained by Vlad, letter 26.10.24 17:42
+    (subject: "oddities when use instances of selective statements"):
+    * line 'cur1.execute(ps1)' creates a new cursor but looses reference on it;
+    * but this cursor is linked with instance of ps1 which *has* reference on that cursor;
+    * call 'ps1.free()' delete this anonimous cursor but Python runtime
+      (or - maybe - code that makes connection cleanup) does not know about it
+      and tries to delete this anon cursor AGAIN when code finishes 'with' block.
+      This attempt causes AV.
 """
 
 import pytest
@@ -117,24 +149,33 @@ def test_1(act: Action, capsys):
 
         with connect(db_cfg_name, user = act.db.user, password = act.db.password) as con:
             for idx, test_sql in enumerate(test_query_lst):
+                ps,rs = None, None
                 try:
                     cur = con.cursor()
                     cur.execute("select g.rdb$config_name, g.rdb$config_value from rdb$database r left join rdb$config g on g.rdb$config_name = 'SubQueryConversion'")
                     for r in cur:
                         print(r[0],r[1])
 
+                    
                     ps = cur.prepare(test_sql)
 
                     print(f'\nExample {idx+1}')
                     # Print explained plan with padding eash line by dots in order to see indentations:
                     print( '\n'.join([replace_leading(s) for s in ps.detailed_plan.split('\n')]) )
 
-                    # Print data:
+                    # explained by hvlad, 26.10.24 17:42
-                    for r in cur.execute(ps):
+                    rs = cur.execute(ps)
+                    for r in rs:
+                        # Print data:
                         print(r[0])
                 except DatabaseError as e:
                     print(e.__str__())
                     print(e.gds_codes)
+                finally:
+                    if rs:
+                        rs.close()
+                    if ps:
+                        ps.free()
 
     act.expected_stdout = f"""
         SubQueryConversion true