From 32b76b2e5811117458c05a5c970c98a394205f6f Mon Sep 17 00:00:00 2001
From: pavel-zotov <p519446@yandex.ru>
Date: Sat, 18 Jan 2025 18:04:48 +0300
Subject: [PATCH] Added/Updated tests\bugs\gh_3218_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_3218_test.py | 50 +++++++++++++++++++++++++++++---------
 1 file changed, 39 insertions(+), 11 deletions(-)

diff --git a/tests/bugs/gh_3218_test.py b/tests/bugs/gh_3218_test.py
index 3f148ef9..1fef04ed 100644
--- a/tests/bugs/gh_3218_test.py
+++ b/tests/bugs/gh_3218_test.py
@@ -13,11 +13,20 @@ NOTES:
     [20.01.2024] pzotov
     Confirmed problem on 5.0.0.442: number of indexed reads was equal to the total count of records in rdb$relation_fields.
     Checked on 6.0.0.218, 5.0.1.1318.
+
+    [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").
 """
 
-import pytest
 from pathlib import Path
+
+import pytest
 from firebird.qa import *
+from firebird.driver import DatabaseError
 
 init_sql = """
     set term ^;
@@ -73,22 +82,41 @@ def test_1(act: Action, capsys):
 
         result_map = {}
         chk_sql = 'select 1 from sp_get_relations r join rdb$relation_fields f on f.rdb$relation_name = r.rdb$relation_name where r.rdb$relation_id < 10'
-        with cur.prepare(chk_sql) as ps:
-            cur.execute(chk_sql)
+        ps, rs = None, None
+        try:
+            ps = cur.prepare(chk_sql)
+
+            # ::: 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)
+
             tabstat1 = [ p for p in con.info.get_table_access_stats() if p.table_id == rf_rel_id ]
             cur.fetchall()
             tabstat2 = [ p for p in con.info.get_table_access_stats() if p.table_id == rf_rel_id ]
             print( '\n'.join([replace_leading(s) for s in ps.detailed_plan.split('\n')]) ) # explained plan, with preserving indents by replacing leading spaces with '#'
 
-        idx_reads = (tabstat2[0].indexed if tabstat2[0].indexed else 0)
-        if tabstat1:
-            idx_reads -= (tabstat1[0].indexed if tabstat1[0].indexed else 0)
+            idx_reads = (tabstat2[0].indexed if tabstat2[0].indexed else 0)
+            if tabstat1:
+                idx_reads -= (tabstat1[0].indexed if tabstat1[0].indexed else 0)
 
-        print('Result:')
-        if idx_reads == 0 or idx_reads > cnt_chk:
-            print(f'POOR! Number of records in rdb$relation_fields: 1) to be filtered: {cnt_chk}, 2) total: {cnt_all}. Number of indexed_reads: {idx_reads}')
-        else:
-            print('Acceptable.')
+            print('Result:')
+            if idx_reads == 0 or idx_reads > cnt_chk:
+                print(f'POOR! Number of records in rdb$relation_fields: 1) to be filtered: {cnt_chk}, 2) total: {cnt_all}. Number of indexed_reads: {idx_reads}')
+            else:
+                print('Acceptable.')
+
+        except DatabaseError as e:
+            print( e.__str__() )
+            print(e.gds_codes)
+        finally:
+            if rs:
+                rs.close() # <<< EXPLICITLY CLOSING CURSOR RESULTS
+            if ps:
+                ps.free()
 
     act.expected_stdout = """
         Select Expression