From 028bb337805996ec188c1ddf2a9f81e5d23b2d07 Mon Sep 17 00:00:00 2001
From: pavel-zotov <p519446@yandex.ru>
Date: Sat, 18 Jan 2025 18:10:43 +0300
Subject: [PATCH] Added/Updated tests\bugs\core_2477_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/core_2477_test.py | 72 +++++++++++++++++++++++++-----------
 1 file changed, 51 insertions(+), 21 deletions(-)

diff --git a/tests/bugs/core_2477_test.py b/tests/bugs/core_2477_test.py
index ebaec7bc..adb14aad 100644
--- a/tests/bugs/core_2477_test.py
+++ b/tests/bugs/core_2477_test.py
@@ -21,20 +21,30 @@ DESCRIPTION:
 JIRA:        CORE-2477
 FBTEST:      bugs.core_2477
 NOTES:
-[16.11.2021] pcisar
+    [16.11.2021] pcisar
     This test is too complicated and fragile, and it's IMHO not worth to be implemented
-[24.07.2022] pzotov
+
+    [24.07.2022] pzotov
     Test was totally re-implemented. No async call of ISQL, waiting/killing etc.
 
     Checked on Windows: 3.0.8.33535 (SS/CS), 4.0.1.2692 (SS/CS), 5.0.0.591
     Checked on Linux: 4.0.1.2692 (SS/CS) - needed to increase number of rows to be sorted.
+
+    [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 subprocess
 from pathlib import Path
+from firebird.driver import DatabaseError
+import time
+
 import pytest
 from firebird.qa import *
-import time
 
 init_script = """
     create or alter view v_mon as
@@ -108,27 +118,47 @@ def test_1(act: Action, capsys):
     with act.db.connect() as con_worker:
 
         cur_worker = con_worker.cursor()
-        cur_wrk_ps = cur_worker.prepare(heavy_sql_sttm)
+        cur_wrk_ps, cur_wrk_rs = None, None
 
-        for m in ('beg','end'):
-            with act.db.connect() as con_monitor:
-                cur_monitor=con_monitor.cursor()
-                cur_monitor.execute('select * from v_gather_mon')
-                
-                for r in cur_monitor:
-                    map_result[m] = (r[3], r[7]) # ('idle' | 'stalled', memo_used)
+        try:
+            cur_wrk_ps = cur_worker.prepare(heavy_sql_sttm)
 
-                assert map_result.get(m), f"No rows returned from v_gather_mon for m='{m}'"
-       
-            if m == 'beg':
-                cur_worker.execute(cur_wrk_ps)
-                for i in range(0, ROWS_TO_BE_SORTED):
-                    r = cur_worker.fetchone()
+            for m in ('beg','end'):
+                with act.db.connect() as con_monitor:
+                    cur_monitor=con_monitor.cursor()
+                    cur_monitor.execute('select * from v_gather_mon')
+                    
+                    for r in cur_monitor:
+                        map_result[m] = (r[3], r[7]) # ('idle' | 'stalled', memo_used)
 
-                # After this loop statement with huge sort will remain in stalled state
-                # (its mon$statements.mon$state must be 2).
-                # We can now gather mon$ info second time (in a NEW connection)
-                # and then evaluate DIFFERENCE.
+                    assert map_result.get(m), f"No rows returned from v_gather_mon for m='{m}'"
+           
+                if m == 'beg':
+
+                    # ::: 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
+                    
+                    cur_wrk_rs = cur_worker.execute(cur_wrk_ps)
+                    for i in range(0, ROWS_TO_BE_SORTED):
+                        r = cur_worker.fetchone()
+
+                    # After this loop statement with huge sort will remain in stalled state
+                    # (its mon$statements.mon$state must be 2).
+                    # We can now gather mon$ info second time (in a NEW connection)
+                    # and then evaluate DIFFERENCE.
+
+        except DatabaseError as e:
+            print( e.__str__() )
+            print(e.gds_codes)
+        finally:
+            if cur_wrk_rs:
+                cur_wrk_rs.close() # <<< EXPLICITLY CLOSING CURSOR RESULTS
+            if cur_wrk_ps:
+                cur_wrk_ps.free()
 
     #------------------------------------------------------------------------------------------