Added/Updated tests\bugs\gh_6947_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_6947_test.py

@@ -28,6 +28,13 @@ NOTES:
     [11.03.2023] pzotov
     Marked as SKIPPED because covered by core_6048_test.
     Probably will be deleted soon.
+
+    [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 os
 import datetime as py_dt
@@ -118,8 +125,9 @@ def test_1(act: Action, capsys):
         cur = con.cursor()
         cu2 = con.cursor()
 
+        ps, rs = None, None
+        try:
             ps = cur.prepare('select mon$crypt_page from mon$database')
-
             while encryption_started:
                 t2=py_dt.datetime.now()
                 d1=t2-t1
@@ -127,8 +135,16 @@ def test_1(act: Action, capsys):
                     print(f'TIMEOUT EXPIRATION: encryption took {d1.seconds*1000 + d1.microseconds//1000} ms which exceeds limit = {MAX_WAITING_ENCR_FINISH} ms.')
                     break
 
-            cur.execute(ps)
+                # ::: NB ::: 'ps' returns data, i.e. this is SELECTABLE expression.
-            p = cur.fetchone()[0]
+                # 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:
+                    p = r[0]
+
                 cu2.callproc('sp_tmp', [ p, ] )
                 con.commit()
 
@@ -150,6 +166,16 @@ def test_1(act: Action, capsys):
                         break
                 act.reset()
 
+        except DatabaseError as e:
+            print( e.__str__() )
+            print(e.gds_codes)
+        finally:
+            if rs:
+                rs.close() # <<< EXPLICITLY CLOSING CURSOR RESULTS
+            if ps:
+                ps.free()
+
+    
     if encryption_started:
         if len(encrypted_pages_set) >= MIN_DISTINCT_ENCRYPTED_PAGES:
             print(expected_stdout)