From 3d481c81bbb5d8d86443c1e098b912fcb6b92cf5 Mon Sep 17 00:00:00 2001
From: ebonnal <bonnal.enzo.dev@gmail.com>
Date: Mon, 24 Mar 2025 23:49:31 +0000
Subject: [PATCH 01/41] =?UTF-8?q?`test=5Fconcurrent=5Ffutures.test=5Fmap?=
 =?UTF-8?q?=5Fexception`:=20assert=20no=20reference=20cycle=20from=20faile?=
 =?UTF-8?q?d=20future=20captured=20in=20its=20exception=E2=80=99s=20traceb?=
 =?UTF-8?q?ack?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 Lib/test/test_concurrent_futures/executor.py | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/Lib/test/test_concurrent_futures/executor.py b/Lib/test/test_concurrent_futures/executor.py
index ff7bd0db0c2199c..d739ae7a526e342 100644
--- a/Lib/test/test_concurrent_futures/executor.py
+++ b/Lib/test/test_concurrent_futures/executor.py
@@ -1,3 +1,4 @@
+import gc
 import itertools
 import threading
 import time
@@ -80,7 +81,20 @@ def test_map_exception(self):
         i = self.executor.map(divmod, [5, 5, 5, 5], [2, 3, 0, 5])
         self.assertEqual(next(i), (2, 1))
         self.assertEqual(next(i), (1, 2))
-        self.assertRaises(ZeroDivisionError, next, i)
+
+        error = None
+        try:
+            next(i)
+        except ZeroDivisionError as zero_div_error:
+            error = zero_div_error
+        self.assertIsNotNone(
+            error,
+            msg="next one should raise a ZeroDivisionError",
+        )
+
+        # a failed future must not be captured in its
+        # future._exception.__traceback__ to avoid a reference cycle
+        self.assertFalse(gc.get_referrers(error))
         self.assertEqual(next(i), (1, 0))
         self.assertRaises(StopIteration, next, i)
         self.assertRaises(StopIteration, next, i)

From f6f08a6159a6e536520594855b5b8a5dad92e127 Mon Sep 17 00:00:00 2001
From: ebonnal <bonnal.enzo.dev@gmail.com>
Date: Tue, 25 Mar 2025 00:33:59 +0000
Subject: [PATCH 02/41] test there is no future in referrers

---
 Lib/test/test_concurrent_futures/executor.py | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/Lib/test/test_concurrent_futures/executor.py b/Lib/test/test_concurrent_futures/executor.py
index d739ae7a526e342..a97cc40f48df822 100644
--- a/Lib/test/test_concurrent_futures/executor.py
+++ b/Lib/test/test_concurrent_futures/executor.py
@@ -94,7 +94,12 @@ def test_map_exception(self):
 
         # a failed future must not be captured in its
         # future._exception.__traceback__ to avoid a reference cycle
-        self.assertFalse(gc.get_referrers(error))
+        self.assertFalse(
+            any(
+                isinstance(referrer, futures.Future)
+                for referrer in gc.get_referrers(error)
+            )
+        )
         self.assertEqual(next(i), (1, 0))
         self.assertRaises(StopIteration, next, i)
         self.assertRaises(StopIteration, next, i)

From a7a595ddf14905aaf85cde256ec8b2d2efe7c441 Mon Sep 17 00:00:00 2001
From: ebonnal <bonnal.enzo.dev@gmail.com>
Date: Tue, 25 Mar 2025 01:42:12 +0000
Subject: [PATCH 03/41] switch to assertTrue(all(...))

---
 Lib/test/test_concurrent_futures/executor.py | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/Lib/test/test_concurrent_futures/executor.py b/Lib/test/test_concurrent_futures/executor.py
index a97cc40f48df822..60dba51b179dcfd 100644
--- a/Lib/test/test_concurrent_futures/executor.py
+++ b/Lib/test/test_concurrent_futures/executor.py
@@ -94,9 +94,9 @@ def test_map_exception(self):
 
         # a failed future must not be captured in its
         # future._exception.__traceback__ to avoid a reference cycle
-        self.assertFalse(
-            any(
-                isinstance(referrer, futures.Future)
+        self.assertTrue(
+            all(
+                not isinstance(referrer, futures.Future)
                 for referrer in gc.get_referrers(error)
             )
         )

From 984d228e9bfd99625f238a46b72d9bcf425cc445 Mon Sep 17 00:00:00 2001
From: ebonnal <bonnal.enzo.dev@gmail.com>
Date: Tue, 25 Mar 2025 11:12:36 +0000
Subject: [PATCH 04/41] add test msg

---
 Lib/test/test_concurrent_futures/executor.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/Lib/test/test_concurrent_futures/executor.py b/Lib/test/test_concurrent_futures/executor.py
index 60dba51b179dcfd..c559a31f5449565 100644
--- a/Lib/test/test_concurrent_futures/executor.py
+++ b/Lib/test/test_concurrent_futures/executor.py
@@ -98,7 +98,8 @@ def test_map_exception(self):
             all(
                 not isinstance(referrer, futures.Future)
                 for referrer in gc.get_referrers(error)
-            )
+            ),
+            msg="none of the referrers should be a Future.",
         )
         self.assertEqual(next(i), (1, 0))
         self.assertRaises(StopIteration, next, i)

From 4cd4820826b7abf6dacdd7246d9b1ec15f505bbc Mon Sep 17 00:00:00 2001
From: ebonnal <bonnal.enzo.dev@gmail.com>
Date: Tue, 25 Mar 2025 11:14:03 +0000
Subject: [PATCH 05/41] format msgs

---
 Lib/test/test_concurrent_futures/executor.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Lib/test/test_concurrent_futures/executor.py b/Lib/test/test_concurrent_futures/executor.py
index c559a31f5449565..048654d81b7c5d2 100644
--- a/Lib/test/test_concurrent_futures/executor.py
+++ b/Lib/test/test_concurrent_futures/executor.py
@@ -99,7 +99,7 @@ def test_map_exception(self):
                 not isinstance(referrer, futures.Future)
                 for referrer in gc.get_referrers(error)
             ),
-            msg="none of the referrers should be a Future.",
+            msg="none of the referrers should be a Future",
         )
         self.assertEqual(next(i), (1, 0))
         self.assertRaises(StopIteration, next, i)
@@ -232,7 +232,7 @@ def test_map_buffersize_when_buffer_is_full(self):
         self.assertEqual(
             next(ints),
             buffersize,
-            msg="should have fetched only `buffersize` elements from `ints`.",
+            msg="should have fetched only `buffersize` elements from `ints`",
         )
 
     @warnings_helper.ignore_fork_in_thread_deprecation_warnings()

From b7551c8082b7c3c2af2a0eef1e43851916da0464 Mon Sep 17 00:00:00 2001
From: ebonnal <bonnal.enzo.dev@gmail.com>
Date: Tue, 25 Mar 2025 11:23:58 +0000
Subject: [PATCH 06/41] switch to assert list empty for a better assertion
 error message

---
 Lib/test/test_concurrent_futures/executor.py | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/Lib/test/test_concurrent_futures/executor.py b/Lib/test/test_concurrent_futures/executor.py
index 048654d81b7c5d2..868b42512e7f669 100644
--- a/Lib/test/test_concurrent_futures/executor.py
+++ b/Lib/test/test_concurrent_futures/executor.py
@@ -94,11 +94,12 @@ def test_map_exception(self):
 
         # a failed future must not be captured in its
         # future._exception.__traceback__ to avoid a reference cycle
-        self.assertTrue(
-            all(
-                not isinstance(referrer, futures.Future)
+        self.assertFalse(
+            [
+                referrer
                 for referrer in gc.get_referrers(error)
-            ),
+                if isinstance(referrer, futures.Future)
+            ],
             msg="none of the referrers should be a Future",
         )
         self.assertEqual(next(i), (1, 0))

From ec2b0289eadf373d004a76210b7531891d9d3cf6 Mon Sep 17 00:00:00 2001
From: ebonnal <bonnal.enzo.dev@gmail.com>
Date: Wed, 26 Mar 2025 22:49:32 +0000
Subject: [PATCH 07/41] edit comment

---
 Lib/test/test_concurrent_futures/executor.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Lib/test/test_concurrent_futures/executor.py b/Lib/test/test_concurrent_futures/executor.py
index 868b42512e7f669..717c09fa2dd9ebf 100644
--- a/Lib/test/test_concurrent_futures/executor.py
+++ b/Lib/test/test_concurrent_futures/executor.py
@@ -92,7 +92,7 @@ def test_map_exception(self):
             msg="next one should raise a ZeroDivisionError",
         )
 
-        # a failed future must not be captured in its
+        # a failed future should not be captured in its
         # future._exception.__traceback__ to avoid a reference cycle
         self.assertFalse(
             [

From 171e083f6d3f4f9b6a2002dc3b3199144f89124a Mon Sep 17 00:00:00 2001
From: Thomas Grainger <tagrain@gmail.com>
Date: Sun, 30 Mar 2025 13:48:04 +0100
Subject: [PATCH 08/41] assert there are no reference cycles at all

---
 Lib/test/test_concurrent_futures/executor.py | 9 +--------
 1 file changed, 1 insertion(+), 8 deletions(-)

diff --git a/Lib/test/test_concurrent_futures/executor.py b/Lib/test/test_concurrent_futures/executor.py
index 717c09fa2dd9ebf..02ee9c6f43999d2 100644
--- a/Lib/test/test_concurrent_futures/executor.py
+++ b/Lib/test/test_concurrent_futures/executor.py
@@ -94,14 +94,7 @@ def test_map_exception(self):
 
         # a failed future should not be captured in its
         # future._exception.__traceback__ to avoid a reference cycle
-        self.assertFalse(
-            [
-                referrer
-                for referrer in gc.get_referrers(error)
-                if isinstance(referrer, futures.Future)
-            ],
-            msg="none of the referrers should be a Future",
-        )
+        self.assertListEqual(gc.get_referrers(error), [])
         self.assertEqual(next(i), (1, 0))
         self.assertRaises(StopIteration, next, i)
         self.assertRaises(StopIteration, next, i)

From 9710843a5d843c10ddc96b11d89eeaf3039e5969 Mon Sep 17 00:00:00 2001
From: ebonnal <bonnal.enzo.dev@gmail.com>
Date: Sun, 30 Mar 2025 21:20:37 +0100
Subject: [PATCH 09/41] test that traceback frames should not contain any
 variables referring to an Exception or a failed Future

---
 Lib/test/test_concurrent_futures/executor.py | 19 ++++++++++++++++---
 1 file changed, 16 insertions(+), 3 deletions(-)

diff --git a/Lib/test/test_concurrent_futures/executor.py b/Lib/test/test_concurrent_futures/executor.py
index 02ee9c6f43999d2..e414d7cb4e5a797 100644
--- a/Lib/test/test_concurrent_futures/executor.py
+++ b/Lib/test/test_concurrent_futures/executor.py
@@ -92,9 +92,22 @@ def test_map_exception(self):
             msg="next one should raise a ZeroDivisionError",
         )
 
-        # a failed future should not be captured in its
-        # future._exception.__traceback__ to avoid a reference cycle
-        self.assertListEqual(gc.get_referrers(error), [])
+        self.assertFalse(
+            gc.get_referrers(error),
+            msg="the raised error should not have any referrer",
+        )
+
+        tb = error.__traceback__
+        while (tb := tb.tb_next):
+            self.assertFalse(
+                {
+                    var: val
+                    for var, val in tb.tb_frame.f_locals.items()
+                    if isinstance(val, Exception)
+                    or (isinstance(val, futures.Future) and val.exception())
+                },
+                msg=f"traceback frames should not contain any variables referring to an Exception or a failed Future",
+            )
         self.assertEqual(next(i), (1, 0))
         self.assertRaises(StopIteration, next, i)
         self.assertRaises(StopIteration, next, i)

From 00e7aee198a5c40f20d3b1e426148570d0a73721 Mon Sep 17 00:00:00 2001
From: ebonnal <bonnal.enzo.dev@gmail.com>
Date: Sun, 30 Mar 2025 21:29:05 +0100
Subject: [PATCH 10/41] interpreter.WorkerContext.run: finally unassign
 exc_wrapper

---
 Lib/concurrent/futures/interpreter.py | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/Lib/concurrent/futures/interpreter.py b/Lib/concurrent/futures/interpreter.py
index fd3d45144b49a71..df1ece324c2e09a 100644
--- a/Lib/concurrent/futures/interpreter.py
+++ b/Lib/concurrent/futures/interpreter.py
@@ -88,7 +88,10 @@ def run(self, task):
             if exc is None:
                 # The exception must have been not shareable.
                 raise  # re-raise
-            raise exc from wrapper
+            try:
+                raise exc from wrapper
+            finally:
+                exc = None
 
 
 class BrokenInterpreterPool(_thread.BrokenThreadPool):

From c62b24e81c0ff816bc31659cb0fa7f873de00e97 Mon Sep 17 00:00:00 2001
From: ebonnal <bonnal.enzo.dev@gmail.com>
Date: Sun, 30 Mar 2025 21:31:30 +0100
Subject: [PATCH 11/41] fix msg grammar

---
 Lib/test/test_concurrent_futures/executor.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Lib/test/test_concurrent_futures/executor.py b/Lib/test/test_concurrent_futures/executor.py
index e414d7cb4e5a797..d55bcef682783db 100644
--- a/Lib/test/test_concurrent_futures/executor.py
+++ b/Lib/test/test_concurrent_futures/executor.py
@@ -94,7 +94,7 @@ def test_map_exception(self):
 
         self.assertFalse(
             gc.get_referrers(error),
-            msg="the raised error should not have any referrer",
+            msg="the raised error should not have any referrers",
         )
 
         tb = error.__traceback__

From a3046c150d0db3e9c68b1f2ab02b4cbb83ee8940 Mon Sep 17 00:00:00 2001
From: ebonnal <bonnal.enzo.dev@gmail.com>
Date: Sun, 30 Mar 2025 21:47:00 +0100
Subject: [PATCH 12/41] fix access to exception

---
 Lib/test/test_concurrent_futures/executor.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Lib/test/test_concurrent_futures/executor.py b/Lib/test/test_concurrent_futures/executor.py
index d55bcef682783db..0cc8e5824a0a1a6 100644
--- a/Lib/test/test_concurrent_futures/executor.py
+++ b/Lib/test/test_concurrent_futures/executor.py
@@ -104,7 +104,7 @@ def test_map_exception(self):
                     var: val
                     for var, val in tb.tb_frame.f_locals.items()
                     if isinstance(val, Exception)
-                    or (isinstance(val, futures.Future) and val.exception())
+                    or (isinstance(val, futures.Future) and val._exception)
                 },
                 msg=f"traceback frames should not contain any variables referring to an Exception or a failed Future",
             )

From 7b1021aedc24d224f1c840ed82493de4127c8488 Mon Sep 17 00:00:00 2001
From: ebonnal <bonnal.enzo.dev@gmail.com>
Date: Sun, 30 Mar 2025 22:34:57 +0100
Subject: [PATCH 13/41] narrow test: traceback frames should not contain any
 exception

---
 Lib/test/test_concurrent_futures/executor.py | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/Lib/test/test_concurrent_futures/executor.py b/Lib/test/test_concurrent_futures/executor.py
index 0cc8e5824a0a1a6..07953d2e1595631 100644
--- a/Lib/test/test_concurrent_futures/executor.py
+++ b/Lib/test/test_concurrent_futures/executor.py
@@ -104,9 +104,8 @@ def test_map_exception(self):
                     var: val
                     for var, val in tb.tb_frame.f_locals.items()
                     if isinstance(val, Exception)
-                    or (isinstance(val, futures.Future) and val._exception)
                 },
-                msg=f"traceback frames should not contain any variables referring to an Exception or a failed Future",
+                msg=f"traceback frames should not contain any exception",
             )
         self.assertEqual(next(i), (1, 0))
         self.assertRaises(StopIteration, next, i)

From e617e82c39ae6ac6ee6665cdd56c98666a3d7168 Mon Sep 17 00:00:00 2001
From: ebonnal <bonnal.enzo.dev@gmail.com>
Date: Mon, 31 Mar 2025 10:53:39 +0100
Subject: [PATCH 14/41] test_map_exception: only search for exception that
 captures itself in its own traceback

---
 Lib/test/test_concurrent_futures/executor.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/Lib/test/test_concurrent_futures/executor.py b/Lib/test/test_concurrent_futures/executor.py
index 07953d2e1595631..899bc562e90a078 100644
--- a/Lib/test/test_concurrent_futures/executor.py
+++ b/Lib/test/test_concurrent_futures/executor.py
@@ -104,8 +104,9 @@ def test_map_exception(self):
                     var: val
                     for var, val in tb.tb_frame.f_locals.items()
                     if isinstance(val, Exception)
+                    and var in val.__traceback__.tb_frame.f_locals
                 },
-                msg=f"traceback frames should not contain any exception",
+                msg=f"the raised exception's traceback should not contain an exception that captures itself in its own traceback",
             )
         self.assertEqual(next(i), (1, 0))
         self.assertRaises(StopIteration, next, i)

From f2e4dbe04fe715e172e507919853272d41c57988 Mon Sep 17 00:00:00 2001
From: ebonnal <bonnal.enzo.dev@gmail.com>
Date: Mon, 31 Mar 2025 11:42:27 +0100
Subject: [PATCH 15/41] concurrent.futures.process: avoid ref cycle in
 _sendback_result

---
 Lib/concurrent/futures/process.py | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/Lib/concurrent/futures/process.py b/Lib/concurrent/futures/process.py
index 7f4f225c0ad4fbd..20ad281eaf25d82 100644
--- a/Lib/concurrent/futures/process.py
+++ b/Lib/concurrent/futures/process.py
@@ -218,9 +218,13 @@ def _sendback_result(result_queue, work_id, result=None, exception=None,
         result_queue.put(_ResultItem(work_id, result=result,
                                      exception=exception, exit_pid=exit_pid))
     except BaseException as e:
-        exc = _ExceptionWithTraceback(e, e.__traceback__)
-        result_queue.put(_ResultItem(work_id, exception=exc,
-                                     exit_pid=exit_pid))
+        result_queue.put(
+            _ResultItem(
+                work_id,
+                exception=_ExceptionWithTraceback(e, e.__traceback__),
+                exit_pid=exit_pid
+            )
+        )
 
 
 def _process_worker(call_queue, result_queue, initializer, initargs, max_tasks=None):

From 1245a9a95227f2d92273a2a34d0f6a271c7c3a7b Mon Sep 17 00:00:00 2001
From: ebonnal <bonnal.enzo.dev@gmail.com>
Date: Mon, 31 Mar 2025 11:43:47 +0100
Subject: [PATCH 16/41] concurrent.futures.process: avoid ref cycle in
 _process_worker

---
 Lib/concurrent/futures/process.py | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/Lib/concurrent/futures/process.py b/Lib/concurrent/futures/process.py
index 20ad281eaf25d82..6b302763ea5ddcb 100644
--- a/Lib/concurrent/futures/process.py
+++ b/Lib/concurrent/futures/process.py
@@ -265,9 +265,12 @@ def _process_worker(call_queue, result_queue, initializer, initargs, max_tasks=N
         try:
             r = call_item.fn(*call_item.args, **call_item.kwargs)
         except BaseException as e:
-            exc = _ExceptionWithTraceback(e, e.__traceback__)
-            _sendback_result(result_queue, call_item.work_id, exception=exc,
-                             exit_pid=exit_pid)
+            _sendback_result(
+                result_queue,
+                call_item.work_id,
+                exception=_ExceptionWithTraceback(e, e.__traceback__),
+                exit_pid=exit_pid,
+            )
         else:
             _sendback_result(result_queue, call_item.work_id, result=r,
                              exit_pid=exit_pid)

From e9845926694994bf62c696a05f1790588079b2db Mon Sep 17 00:00:00 2001
From: ebonnal <bonnal.enzo.dev@gmail.com>
Date: Mon, 31 Mar 2025 12:27:17 +0100
Subject: [PATCH 17/41] format test msg

---
 Lib/test/test_concurrent_futures/executor.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Lib/test/test_concurrent_futures/executor.py b/Lib/test/test_concurrent_futures/executor.py
index 899bc562e90a078..0bfad3f5f4406d7 100644
--- a/Lib/test/test_concurrent_futures/executor.py
+++ b/Lib/test/test_concurrent_futures/executor.py
@@ -94,7 +94,7 @@ def test_map_exception(self):
 
         self.assertFalse(
             gc.get_referrers(error),
-            msg="the raised error should not have any referrers",
+            msg="the exception should not have any referrers",
         )
 
         tb = error.__traceback__
@@ -106,7 +106,7 @@ def test_map_exception(self):
                     if isinstance(val, Exception)
                     and var in val.__traceback__.tb_frame.f_locals
                 },
-                msg=f"the raised exception's traceback should not contain an exception that captures itself in its own traceback",
+                msg=f"the exception's traceback should not contain an exception that captures itself in its own traceback",
             )
         self.assertEqual(next(i), (1, 0))
         self.assertRaises(StopIteration, next, i)

From d3dee343569725f992d00f03c20c025f2749b100 Mon Sep 17 00:00:00 2001
From: ebonnal <bonnal.enzo.dev@gmail.com>
Date: Mon, 31 Mar 2025 12:30:04 +0100
Subject: [PATCH 18/41] refactor ZeroDivisionError assert

---
 Lib/test/test_concurrent_futures/executor.py | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/Lib/test/test_concurrent_futures/executor.py b/Lib/test/test_concurrent_futures/executor.py
index 0bfad3f5f4406d7..544cd04ad34de69 100644
--- a/Lib/test/test_concurrent_futures/executor.py
+++ b/Lib/test/test_concurrent_futures/executor.py
@@ -85,11 +85,11 @@ def test_map_exception(self):
         error = None
         try:
             next(i)
-        except ZeroDivisionError as zero_div_error:
-            error = zero_div_error
-        self.assertIsNotNone(
-            error,
-            msg="next one should raise a ZeroDivisionError",
+        except Exception as e:
+            error = e
+        self.assertTrue(
+            isinstance(error, ZeroDivisionError),
+            msg="next should raise a ZeroDivisionError",
         )
 
         self.assertFalse(

From fc2a3517d6aeac4195f4e96780d5247c228f7c3c Mon Sep 17 00:00:00 2001
From: ebonnal <bonnal.enzo.dev@gmail.com>
Date: Mon, 31 Mar 2025 12:49:22 +0100
Subject: [PATCH 19/41] Revert "concurrent.futures.process: avoid ref cycle in
 _process_worker"

This reverts commit 09b08197db97ad31e23289e7cbb920e41c8706af.
---
 Lib/concurrent/futures/process.py | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/Lib/concurrent/futures/process.py b/Lib/concurrent/futures/process.py
index 6b302763ea5ddcb..20ad281eaf25d82 100644
--- a/Lib/concurrent/futures/process.py
+++ b/Lib/concurrent/futures/process.py
@@ -265,12 +265,9 @@ def _process_worker(call_queue, result_queue, initializer, initargs, max_tasks=N
         try:
             r = call_item.fn(*call_item.args, **call_item.kwargs)
         except BaseException as e:
-            _sendback_result(
-                result_queue,
-                call_item.work_id,
-                exception=_ExceptionWithTraceback(e, e.__traceback__),
-                exit_pid=exit_pid,
-            )
+            exc = _ExceptionWithTraceback(e, e.__traceback__)
+            _sendback_result(result_queue, call_item.work_id, exception=exc,
+                             exit_pid=exit_pid)
         else:
             _sendback_result(result_queue, call_item.work_id, result=r,
                              exit_pid=exit_pid)

From 2e2902093e1de56ca04e536277e86b86d3e2092b Mon Sep 17 00:00:00 2001
From: ebonnal <bonnal.enzo.dev@gmail.com>
Date: Mon, 31 Mar 2025 12:49:37 +0100
Subject: [PATCH 20/41] Revert "concurrent.futures.process: avoid ref cycle in
 _sendback_result"

This reverts commit ef301226c144bc92c64f3bbc5fb78a8c6177d298.
---
 Lib/concurrent/futures/process.py | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/Lib/concurrent/futures/process.py b/Lib/concurrent/futures/process.py
index 20ad281eaf25d82..7f4f225c0ad4fbd 100644
--- a/Lib/concurrent/futures/process.py
+++ b/Lib/concurrent/futures/process.py
@@ -218,13 +218,9 @@ def _sendback_result(result_queue, work_id, result=None, exception=None,
         result_queue.put(_ResultItem(work_id, result=result,
                                      exception=exception, exit_pid=exit_pid))
     except BaseException as e:
-        result_queue.put(
-            _ResultItem(
-                work_id,
-                exception=_ExceptionWithTraceback(e, e.__traceback__),
-                exit_pid=exit_pid
-            )
-        )
+        exc = _ExceptionWithTraceback(e, e.__traceback__)
+        result_queue.put(_ResultItem(work_id, exception=exc,
+                                     exit_pid=exit_pid))
 
 
 def _process_worker(call_queue, result_queue, initializer, initargs, max_tasks=None):

From 51269d90b57e2b310807d681069c071d89686d60 Mon Sep 17 00:00:00 2001
From: ebonnal <bonnal.enzo.dev@gmail.com>
Date: Tue, 1 Apr 2025 00:01:37 +0100
Subject: [PATCH 21/41] skip referrers test for free-threading build on
 win/linux

---
 Lib/test/test_concurrent_futures/executor.py | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/Lib/test/test_concurrent_futures/executor.py b/Lib/test/test_concurrent_futures/executor.py
index 544cd04ad34de69..b0669516707c510 100644
--- a/Lib/test/test_concurrent_futures/executor.py
+++ b/Lib/test/test_concurrent_futures/executor.py
@@ -1,10 +1,12 @@
 import gc
 import itertools
+import sys
 import threading
 import time
 import weakref
 from concurrent import futures
 from operator import add
+from sysconfig import get_config_var
 from test import support
 from test.support import Py_GIL_DISABLED, warnings_helper
 
@@ -92,10 +94,13 @@ def test_map_exception(self):
             msg="next should raise a ZeroDivisionError",
         )
 
-        self.assertFalse(
-            gc.get_referrers(error),
-            msg="the exception should not have any referrers",
-        )
+        # some referrers may remain for free-threading build on Windows/Linux
+        is_free_threading = '--disable-gil' in get_config_var("CONFIG_ARGS")
+        if not is_free_threading or sys.platform not in ("linux", "win32"):
+            self.assertFalse(
+                gc.get_referrers(error),
+                msg="the exception should not have any referrers",
+            )
 
         tb = error.__traceback__
         while (tb := tb.tb_next):

From ed0e87f8b09175ede0d3cb2aa464b2b1fc56a116 Mon Sep 17 00:00:00 2001
From: ebonnal <bonnal.enzo.dev@gmail.com>
Date: Tue, 1 Apr 2025 00:16:11 +0100
Subject: [PATCH 22/41] call gc.collect for free-threading on linux/windows

---
 Lib/test/test_concurrent_futures/executor.py | 18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/Lib/test/test_concurrent_futures/executor.py b/Lib/test/test_concurrent_futures/executor.py
index b0669516707c510..75b4a521fe19f55 100644
--- a/Lib/test/test_concurrent_futures/executor.py
+++ b/Lib/test/test_concurrent_futures/executor.py
@@ -94,13 +94,17 @@ def test_map_exception(self):
             msg="next should raise a ZeroDivisionError",
         )
 
-        # some referrers may remain for free-threading build on Windows/Linux
-        is_free_threading = '--disable-gil' in get_config_var("CONFIG_ARGS")
-        if not is_free_threading or sys.platform not in ("linux", "win32"):
-            self.assertFalse(
-                gc.get_referrers(error),
-                msg="the exception should not have any referrers",
-            )
+        # a GC collection may be necessary for free-threading build on Windows/Linux
+        if (
+            '--disable-gil' in get_config_var("CONFIG_ARGS")
+            and sys.platform in ("linux", "win32")
+        ):
+            gc.collect()
+
+        self.assertFalse(
+            gc.get_referrers(error),
+            msg="the exception should not have any referrers",
+        )
 
         tb = error.__traceback__
         while (tb := tb.tb_next):

From b3f3f4a3b080d62b5e997da91cf1097e91efcccf Mon Sep 17 00:00:00 2001
From: ebonnal <bonnal.enzo.dev@gmail.com>
Date: Tue, 1 Apr 2025 11:52:20 +0100
Subject: [PATCH 23/41] Revert "call gc.collect for free-threading on
 linux/windows"

This reverts commit cae64747fa2954c8cf868695beb094ebee40032c.
---
 Lib/test/test_concurrent_futures/executor.py | 18 +++++++-----------
 1 file changed, 7 insertions(+), 11 deletions(-)

diff --git a/Lib/test/test_concurrent_futures/executor.py b/Lib/test/test_concurrent_futures/executor.py
index 75b4a521fe19f55..b0669516707c510 100644
--- a/Lib/test/test_concurrent_futures/executor.py
+++ b/Lib/test/test_concurrent_futures/executor.py
@@ -94,17 +94,13 @@ def test_map_exception(self):
             msg="next should raise a ZeroDivisionError",
         )
 
-        # a GC collection may be necessary for free-threading build on Windows/Linux
-        if (
-            '--disable-gil' in get_config_var("CONFIG_ARGS")
-            and sys.platform in ("linux", "win32")
-        ):
-            gc.collect()
-
-        self.assertFalse(
-            gc.get_referrers(error),
-            msg="the exception should not have any referrers",
-        )
+        # some referrers may remain for free-threading build on Windows/Linux
+        is_free_threading = '--disable-gil' in get_config_var("CONFIG_ARGS")
+        if not is_free_threading or sys.platform not in ("linux", "win32"):
+            self.assertFalse(
+                gc.get_referrers(error),
+                msg="the exception should not have any referrers",
+            )
 
         tb = error.__traceback__
         while (tb := tb.tb_next):

From e3e75cee9599cfc86bbf738570e3442b9721df08 Mon Sep 17 00:00:00 2001
From: ebonnal <bonnal.enzo.dev@gmail.com>
Date: Tue, 1 Apr 2025 11:52:30 +0100
Subject: [PATCH 24/41] Revert "skip referrers test for free-threading build on
 win/linux"

This reverts commit fc7a569a71d53722f40b31a61018541847aa976b.
---
 Lib/test/test_concurrent_futures/executor.py | 13 ++++---------
 1 file changed, 4 insertions(+), 9 deletions(-)

diff --git a/Lib/test/test_concurrent_futures/executor.py b/Lib/test/test_concurrent_futures/executor.py
index b0669516707c510..544cd04ad34de69 100644
--- a/Lib/test/test_concurrent_futures/executor.py
+++ b/Lib/test/test_concurrent_futures/executor.py
@@ -1,12 +1,10 @@
 import gc
 import itertools
-import sys
 import threading
 import time
 import weakref
 from concurrent import futures
 from operator import add
-from sysconfig import get_config_var
 from test import support
 from test.support import Py_GIL_DISABLED, warnings_helper
 
@@ -94,13 +92,10 @@ def test_map_exception(self):
             msg="next should raise a ZeroDivisionError",
         )
 
-        # some referrers may remain for free-threading build on Windows/Linux
-        is_free_threading = '--disable-gil' in get_config_var("CONFIG_ARGS")
-        if not is_free_threading or sys.platform not in ("linux", "win32"):
-            self.assertFalse(
-                gc.get_referrers(error),
-                msg="the exception should not have any referrers",
-            )
+        self.assertFalse(
+            gc.get_referrers(error),
+            msg="the exception should not have any referrers",
+        )
 
         tb = error.__traceback__
         while (tb := tb.tb_next):

From 70e22a1c8044adbdaf4d0d42232e52060fb5f08f Mon Sep 17 00:00:00 2001
From: Thomas Grainger <tagrain@gmail.com>
Date: Thu, 3 Apr 2025 08:40:08 +0100
Subject: [PATCH 25/41] more gc referrers

---
 Lib/test/test_concurrent_futures/executor.py | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/Lib/test/test_concurrent_futures/executor.py b/Lib/test/test_concurrent_futures/executor.py
index 544cd04ad34de69..c1ddee717e954b5 100644
--- a/Lib/test/test_concurrent_futures/executor.py
+++ b/Lib/test/test_concurrent_futures/executor.py
@@ -6,7 +6,7 @@
 from concurrent import futures
 from operator import add
 from test import support
-from test.support import Py_GIL_DISABLED, warnings_helper
+from test.support import Py_GIL_DISABLED, disable_gc, warnings_helper
 
 
 def mul(x, y):
@@ -77,6 +77,7 @@ def test_map(self):
                 list(map(pow, range(10), range(10))))
 
     @warnings_helper.ignore_fork_in_thread_deprecation_warnings()
+    @disable_gc()
     def test_map_exception(self):
         i = self.executor.map(divmod, [5, 5, 5, 5], [2, 3, 0, 5])
         self.assertEqual(next(i), (2, 1))
@@ -92,8 +93,9 @@ def test_map_exception(self):
             msg="next should raise a ZeroDivisionError",
         )
 
+        # TODO: remove only for debugging
         self.assertFalse(
-            gc.get_referrers(error),
+            [gc.get_referrers(x) for x in gc.get_referrers(error)],
             msg="the exception should not have any referrers",
         )
 

From 12abc0e9bf758dca4cb7fb19844e2db097dcf9fe Mon Sep 17 00:00:00 2001
From: Thomas Grainger <tagrain@gmail.com>
Date: Thu, 3 Apr 2025 09:00:02 +0100
Subject: [PATCH 26/41] even more gc referrers

---
 Lib/test/test_concurrent_futures/executor.py | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/Lib/test/test_concurrent_futures/executor.py b/Lib/test/test_concurrent_futures/executor.py
index c1ddee717e954b5..bc53a32a75d9eb5 100644
--- a/Lib/test/test_concurrent_futures/executor.py
+++ b/Lib/test/test_concurrent_futures/executor.py
@@ -95,7 +95,11 @@ def test_map_exception(self):
 
         # TODO: remove only for debugging
         self.assertFalse(
-            [gc.get_referrers(x) for x in gc.get_referrers(error)],
+            [
+                gc.get_referrers(y)
+                for x in gc.get_referrers(error)
+                for y in gc.get_referrers(x)
+            ],
             msg="the exception should not have any referrers",
         )
 

From cac4aac2bf50ddc3a55c8ffb7ad3c9b988249061 Mon Sep 17 00:00:00 2001
From: Thomas Grainger <tagrain@gmail.com>
Date: Fri, 4 Apr 2025 07:56:24 +0100
Subject: [PATCH 27/41] delete a ref to work_item

---
 Lib/concurrent/futures/process.py | 21 ++++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)

diff --git a/Lib/concurrent/futures/process.py b/Lib/concurrent/futures/process.py
index 7f4f225c0ad4fbd..16f151b411875ee 100644
--- a/Lib/concurrent/futures/process.py
+++ b/Lib/concurrent/futures/process.py
@@ -490,15 +490,18 @@ def add_call_item_to_queue(self):
             else:
                 work_item = self.pending_work_items[work_id]
 
-                if work_item.future.set_running_or_notify_cancel():
-                    self.call_queue.put(_CallItem(work_id,
-                                                  work_item.fn,
-                                                  work_item.args,
-                                                  work_item.kwargs),
-                                        block=True)
-                else:
-                    del self.pending_work_items[work_id]
-                    continue
+                try:
+                    if work_item.future.set_running_or_notify_cancel():
+                        self.call_queue.put(_CallItem(work_id,
+                                                      work_item.fn,
+                                                      work_item.args,
+                                                      work_item.kwargs),
+                                            block=True)
+                    else:
+                        del self.pending_work_items[work_id]
+                        continue
+                finally:
+                    del work_item
 
     def wait_result_broken_or_wakeup(self):
         # Wait for a result to be ready in the result_queue while checking

From 66b98b49cb223d432ef9a6cb26a55f40d3430bce Mon Sep 17 00:00:00 2001
From: Thomas Grainger <tagrain@gmail.com>
Date: Fri, 4 Apr 2025 08:24:08 +0100
Subject: [PATCH 28/41] delete reference to result_item before joining process

---
 Lib/concurrent/futures/process.py | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/Lib/concurrent/futures/process.py b/Lib/concurrent/futures/process.py
index 16f151b411875ee..2bcebb95d5a1c89 100644
--- a/Lib/concurrent/futures/process.py
+++ b/Lib/concurrent/futures/process.py
@@ -378,16 +378,17 @@ def run(self):
                 return
             if result_item is not None:
                 self.process_result_item(result_item)
-
-                process_exited = result_item.exit_pid is not None
-                if process_exited:
-                    p = self.processes.pop(result_item.exit_pid)
-                    p.join()
+                exit_pid = result_item.exit_pid
 
                 # Delete reference to result_item to avoid keeping references
                 # while waiting on new results.
                 del result_item
 
+                process_exited = exit_pid is not None
+                if process_exited:
+                    p = self.processes.pop(exit_pid)
+                    p.join()
+
                 if process_exited:
                     with self.shutdown_lock:
                         broken = self._replace_dead_worker()

From 68fcecb3c400947c35fe5a2d77724b6d4f59b8b5 Mon Sep 17 00:00:00 2001
From: Thomas Grainger <tagrain@gmail.com>
Date: Fri, 4 Apr 2025 08:45:02 +0100
Subject: [PATCH 29/41] unpack ResultItem and WorkItem

---
 Lib/concurrent/futures/process.py | 36 +++++++++++++++++--------------
 1 file changed, 20 insertions(+), 16 deletions(-)

diff --git a/Lib/concurrent/futures/process.py b/Lib/concurrent/futures/process.py
index 2bcebb95d5a1c89..3d9ccceffff5c0c 100644
--- a/Lib/concurrent/futures/process.py
+++ b/Lib/concurrent/futures/process.py
@@ -377,12 +377,29 @@ def run(self):
                 self.terminate_broken(cause)
                 return
             if result_item is not None:
-                self.process_result_item(result_item)
                 exit_pid = result_item.exit_pid
+                work_id = result_item.work_id
+                exception = result_item.exeption
+                result = result_item.result
+                del result_item
+                # Process the received a result_item. This can be either the PID of a
+                # worker that exited gracefully or a _ResultItem
+
+                # Received a _ResultItem so mark the future as completed.
+                work_item = self.pending_work_items.pop(work_id, None)
+                # work_item can be None if another process terminated (see above)
+                if work_item is not None:
+                    f = work_item.future
+                    del work_item
+                    if exception:
+                        f.set_exception(exception)
+                    else:
+                        f.set_result(result)
+                    del f
 
-                # Delete reference to result_item to avoid keeping references
+                # Delete reference to exception/result to avoid keeping references
                 # while waiting on new results.
-                del result_item
+                del exception, result
 
                 process_exited = exit_pid is not None
                 if process_exited:
@@ -534,19 +551,6 @@ def wait_result_broken_or_wakeup(self):
 
         return result_item, is_broken, cause
 
-    def process_result_item(self, result_item):
-        # Process the received a result_item. This can be either the PID of a
-        # worker that exited gracefully or a _ResultItem
-
-        # Received a _ResultItem so mark the future as completed.
-        work_item = self.pending_work_items.pop(result_item.work_id, None)
-        # work_item can be None if another process terminated (see above)
-        if work_item is not None:
-            if result_item.exception is not None:
-                work_item.future.set_exception(result_item.exception)
-            else:
-                work_item.future.set_result(result_item.result)
-
     def is_shutting_down(self):
         # Check whether we should start shutting down the executor.
         executor = self.executor_reference()

From 0be8f498eae72247aacd255213f63315323be77a Mon Sep 17 00:00:00 2001
From: Thomas Grainger <tagrain@gmail.com>
Date: Sat, 5 Apr 2025 05:48:10 +0100
Subject: [PATCH 30/41] fix typo

---
 Lib/concurrent/futures/process.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Lib/concurrent/futures/process.py b/Lib/concurrent/futures/process.py
index 3d9ccceffff5c0c..2d6da275a8f53fa 100644
--- a/Lib/concurrent/futures/process.py
+++ b/Lib/concurrent/futures/process.py
@@ -379,7 +379,7 @@ def run(self):
             if result_item is not None:
                 exit_pid = result_item.exit_pid
                 work_id = result_item.work_id
-                exception = result_item.exeption
+                exception = result_item.exception
                 result = result_item.result
                 del result_item
                 # Process the received a result_item. This can be either the PID of a

From 6c2406d661e0daa26bbefba14fdb21271041a6d1 Mon Sep 17 00:00:00 2001
From: Thomas Grainger <tagrain@gmail.com>
Date: Sat, 5 Apr 2025 09:30:32 +0100
Subject: [PATCH 31/41] bit of a hack?

---
 Lib/concurrent/futures/process.py | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/Lib/concurrent/futures/process.py b/Lib/concurrent/futures/process.py
index 2d6da275a8f53fa..d673a72be5b08dd 100644
--- a/Lib/concurrent/futures/process.py
+++ b/Lib/concurrent/futures/process.py
@@ -389,13 +389,12 @@ def run(self):
                 work_item = self.pending_work_items.pop(work_id, None)
                 # work_item can be None if another process terminated (see above)
                 if work_item is not None:
-                    f = work_item.future
+                    f_boxed = [work_item.future]
                     del work_item
                     if exception:
-                        f.set_exception(exception)
+                        f_boxed.pop().set_exception(exception)
                     else:
-                        f.set_result(result)
-                    del f
+                        f_boxed.pop().set_result(result)
 
                 # Delete reference to exception/result to avoid keeping references
                 # while waiting on new results.

From 7037c4aa735bb37f84c3658f6b065dd152fe6691 Mon Sep 17 00:00:00 2001
From: ebonnal <bonnal.enzo.dev@gmail.com>
Date: Mon, 7 Apr 2025 11:52:28 +0100
Subject: [PATCH 32/41] Revert investigations

---
 Lib/concurrent/futures/process.py            | 65 +++++++++-----------
 Lib/test/test_concurrent_futures/executor.py | 10 +--
 2 files changed, 31 insertions(+), 44 deletions(-)

diff --git a/Lib/concurrent/futures/process.py b/Lib/concurrent/futures/process.py
index d673a72be5b08dd..7f4f225c0ad4fbd 100644
--- a/Lib/concurrent/futures/process.py
+++ b/Lib/concurrent/futures/process.py
@@ -377,34 +377,17 @@ def run(self):
                 self.terminate_broken(cause)
                 return
             if result_item is not None:
-                exit_pid = result_item.exit_pid
-                work_id = result_item.work_id
-                exception = result_item.exception
-                result = result_item.result
-                del result_item
-                # Process the received a result_item. This can be either the PID of a
-                # worker that exited gracefully or a _ResultItem
-
-                # Received a _ResultItem so mark the future as completed.
-                work_item = self.pending_work_items.pop(work_id, None)
-                # work_item can be None if another process terminated (see above)
-                if work_item is not None:
-                    f_boxed = [work_item.future]
-                    del work_item
-                    if exception:
-                        f_boxed.pop().set_exception(exception)
-                    else:
-                        f_boxed.pop().set_result(result)
-
-                # Delete reference to exception/result to avoid keeping references
-                # while waiting on new results.
-                del exception, result
+                self.process_result_item(result_item)
 
-                process_exited = exit_pid is not None
+                process_exited = result_item.exit_pid is not None
                 if process_exited:
-                    p = self.processes.pop(exit_pid)
+                    p = self.processes.pop(result_item.exit_pid)
                     p.join()
 
+                # Delete reference to result_item to avoid keeping references
+                # while waiting on new results.
+                del result_item
+
                 if process_exited:
                     with self.shutdown_lock:
                         broken = self._replace_dead_worker()
@@ -507,18 +490,15 @@ def add_call_item_to_queue(self):
             else:
                 work_item = self.pending_work_items[work_id]
 
-                try:
-                    if work_item.future.set_running_or_notify_cancel():
-                        self.call_queue.put(_CallItem(work_id,
-                                                      work_item.fn,
-                                                      work_item.args,
-                                                      work_item.kwargs),
-                                            block=True)
-                    else:
-                        del self.pending_work_items[work_id]
-                        continue
-                finally:
-                    del work_item
+                if work_item.future.set_running_or_notify_cancel():
+                    self.call_queue.put(_CallItem(work_id,
+                                                  work_item.fn,
+                                                  work_item.args,
+                                                  work_item.kwargs),
+                                        block=True)
+                else:
+                    del self.pending_work_items[work_id]
+                    continue
 
     def wait_result_broken_or_wakeup(self):
         # Wait for a result to be ready in the result_queue while checking
@@ -550,6 +530,19 @@ def wait_result_broken_or_wakeup(self):
 
         return result_item, is_broken, cause
 
+    def process_result_item(self, result_item):
+        # Process the received a result_item. This can be either the PID of a
+        # worker that exited gracefully or a _ResultItem
+
+        # Received a _ResultItem so mark the future as completed.
+        work_item = self.pending_work_items.pop(result_item.work_id, None)
+        # work_item can be None if another process terminated (see above)
+        if work_item is not None:
+            if result_item.exception is not None:
+                work_item.future.set_exception(result_item.exception)
+            else:
+                work_item.future.set_result(result_item.result)
+
     def is_shutting_down(self):
         # Check whether we should start shutting down the executor.
         executor = self.executor_reference()
diff --git a/Lib/test/test_concurrent_futures/executor.py b/Lib/test/test_concurrent_futures/executor.py
index bc53a32a75d9eb5..544cd04ad34de69 100644
--- a/Lib/test/test_concurrent_futures/executor.py
+++ b/Lib/test/test_concurrent_futures/executor.py
@@ -6,7 +6,7 @@
 from concurrent import futures
 from operator import add
 from test import support
-from test.support import Py_GIL_DISABLED, disable_gc, warnings_helper
+from test.support import Py_GIL_DISABLED, warnings_helper
 
 
 def mul(x, y):
@@ -77,7 +77,6 @@ def test_map(self):
                 list(map(pow, range(10), range(10))))
 
     @warnings_helper.ignore_fork_in_thread_deprecation_warnings()
-    @disable_gc()
     def test_map_exception(self):
         i = self.executor.map(divmod, [5, 5, 5, 5], [2, 3, 0, 5])
         self.assertEqual(next(i), (2, 1))
@@ -93,13 +92,8 @@ def test_map_exception(self):
             msg="next should raise a ZeroDivisionError",
         )
 
-        # TODO: remove only for debugging
         self.assertFalse(
-            [
-                gc.get_referrers(y)
-                for x in gc.get_referrers(error)
-                for y in gc.get_referrers(x)
-            ],
+            gc.get_referrers(error),
             msg="the exception should not have any referrers",
         )
 

From 0568262d5f3457145b82efd16e4d5dd26f99181a Mon Sep 17 00:00:00 2001
From: ebonnal <bonnal.enzo.dev@gmail.com>
Date: Mon, 7 Apr 2025 12:00:15 +0100
Subject: [PATCH 33/41] pause before checking referrers

---
 Lib/test/test_concurrent_futures/executor.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Lib/test/test_concurrent_futures/executor.py b/Lib/test/test_concurrent_futures/executor.py
index 544cd04ad34de69..3e56e0199bca7f4 100644
--- a/Lib/test/test_concurrent_futures/executor.py
+++ b/Lib/test/test_concurrent_futures/executor.py
@@ -92,6 +92,8 @@ def test_map_exception(self):
             msg="next should raise a ZeroDivisionError",
         )
 
+        # free-threading builds need this pause on Ubuntu (ARM) and Windows
+        time.sleep(1)
         self.assertFalse(
             gc.get_referrers(error),
             msg="the exception should not have any referrers",

From cfeaa9b29b7dcd79d11abfce1a2cd9f744163781 Mon Sep 17 00:00:00 2001
From: ebonnal <bonnal.enzo.dev@gmail.com>
Date: Mon, 7 Apr 2025 14:23:39 +0100
Subject: [PATCH 34/41] add comment about the avoided ref cycle with
 exc_wrapper

---
 Lib/concurrent/futures/interpreter.py | 1 +
 Modules/_opcode-488016f1.o.tmp        | 0
 2 files changed, 1 insertion(+)
 create mode 100644 Modules/_opcode-488016f1.o.tmp

diff --git a/Lib/concurrent/futures/interpreter.py b/Lib/concurrent/futures/interpreter.py
index df1ece324c2e09a..be26b40628ee434 100644
--- a/Lib/concurrent/futures/interpreter.py
+++ b/Lib/concurrent/futures/interpreter.py
@@ -91,6 +91,7 @@ def run(self, task):
             try:
                 raise exc from wrapper
             finally:
+                # avoid a ref cycle where exc is captured in its traceback
                 exc = None
 
 
diff --git a/Modules/_opcode-488016f1.o.tmp b/Modules/_opcode-488016f1.o.tmp
new file mode 100644
index 000000000000000..e69de29bb2d1d64

From 346b4eab00654e4c30277ad90420e2cf5898e873 Mon Sep 17 00:00:00 2001
From: ebonnal <bonnal.enzo.dev@gmail.com>
Date: Mon, 7 Apr 2025 14:27:24 +0100
Subject: [PATCH 35/41] format test

---
 Lib/test/test_concurrent_futures/executor.py | 11 ++++++-----
 Modules/_opcode-488016f1.o.tmp               |  0
 2 files changed, 6 insertions(+), 5 deletions(-)
 delete mode 100644 Modules/_opcode-488016f1.o.tmp

diff --git a/Lib/test/test_concurrent_futures/executor.py b/Lib/test/test_concurrent_futures/executor.py
index 3e56e0199bca7f4..e87be7b879ff5a9 100644
--- a/Lib/test/test_concurrent_futures/executor.py
+++ b/Lib/test/test_concurrent_futures/executor.py
@@ -82,24 +82,25 @@ def test_map_exception(self):
         self.assertEqual(next(i), (2, 1))
         self.assertEqual(next(i), (1, 2))
 
-        error = None
+        exception = None
         try:
             next(i)
         except Exception as e:
-            error = e
+            exception = e
         self.assertTrue(
-            isinstance(error, ZeroDivisionError),
+            isinstance(exception, ZeroDivisionError),
             msg="next should raise a ZeroDivisionError",
         )
 
         # free-threading builds need this pause on Ubuntu (ARM) and Windows
         time.sleep(1)
+
         self.assertFalse(
-            gc.get_referrers(error),
+            gc.get_referrers(exception),
             msg="the exception should not have any referrers",
         )
 
-        tb = error.__traceback__
+        tb = exception.__traceback__
         while (tb := tb.tb_next):
             self.assertFalse(
                 {
diff --git a/Modules/_opcode-488016f1.o.tmp b/Modules/_opcode-488016f1.o.tmp
deleted file mode 100644
index e69de29bb2d1d64..000000000000000

From 2a25b9a6ab1a8ffdd671f5b439c0fd34206d5214 Mon Sep 17 00:00:00 2001
From: ebonnal <bonnal.enzo.dev@gmail.com>
Date: Mon, 7 Apr 2025 18:01:48 +0100
Subject: [PATCH 36/41] make the self-captured exceptions check not rely on var
 name

---
 Lib/test/test_concurrent_futures/executor.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Lib/test/test_concurrent_futures/executor.py b/Lib/test/test_concurrent_futures/executor.py
index e87be7b879ff5a9..58165d1ad4ac2cb 100644
--- a/Lib/test/test_concurrent_futures/executor.py
+++ b/Lib/test/test_concurrent_futures/executor.py
@@ -107,7 +107,7 @@ def test_map_exception(self):
                     var: val
                     for var, val in tb.tb_frame.f_locals.items()
                     if isinstance(val, Exception)
-                    and var in val.__traceback__.tb_frame.f_locals
+                    and val.__traceback__.tb_frame is tb.tb_frame
                 },
                 msg=f"the exception's traceback should not contain an exception that captures itself in its own traceback",
             )

From fd9b9bbab70560663813515df11e368d3e311137 Mon Sep 17 00:00:00 2001
From: ebonnal <bonnal.enzo.dev@gmail.com>
Date: Mon, 7 Apr 2025 20:02:29 +0100
Subject: [PATCH 37/41] use traceback.walk_tb

---
 Lib/test/test_concurrent_futures/executor.py | 26 +++++++++++---------
 1 file changed, 14 insertions(+), 12 deletions(-)

diff --git a/Lib/test/test_concurrent_futures/executor.py b/Lib/test/test_concurrent_futures/executor.py
index 58165d1ad4ac2cb..57b77bf053adbfd 100644
--- a/Lib/test/test_concurrent_futures/executor.py
+++ b/Lib/test/test_concurrent_futures/executor.py
@@ -2,9 +2,10 @@
 import itertools
 import threading
 import time
+import traceback
 import weakref
 from concurrent import futures
-from operator import add
+from operator import add, itemgetter
 from test import support
 from test.support import Py_GIL_DISABLED, warnings_helper
 
@@ -100,17 +101,18 @@ def test_map_exception(self):
             msg="the exception should not have any referrers",
         )
 
-        tb = exception.__traceback__
-        while (tb := tb.tb_next):
-            self.assertFalse(
-                {
-                    var: val
-                    for var, val in tb.tb_frame.f_locals.items()
-                    if isinstance(val, Exception)
-                    and val.__traceback__.tb_frame is tb.tb_frame
-                },
-                msg=f"the exception's traceback should not contain an exception that captures itself in its own traceback",
-            )
+        frames = map(itemgetter(0), traceback.walk_tb(exception.__traceback__))
+        next(frames)
+        self.assertFalse(
+            [
+                (var, val)
+                for frame in frames
+                for var, val in frame.f_locals.items()
+                if isinstance(val, Exception)
+                and frame in map(itemgetter(0), traceback.walk_tb(val.__traceback__))
+            ],
+            msg=f"the exception's traceback should not contain an exception that captures itself in its own traceback",
+        )
         self.assertEqual(next(i), (1, 0))
         self.assertRaises(StopIteration, next, i)
         self.assertRaises(StopIteration, next, i)

From 682a7199629759b0e65b5c585a5affc2756511ef Mon Sep 17 00:00:00 2001
From: ebonnal <bonnal.enzo.dev@gmail.com>
Date: Mon, 7 Apr 2025 20:20:48 +0100
Subject: [PATCH 38/41] comment the skipping of the current frame

---
 Lib/test/test_concurrent_futures/executor.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/Lib/test/test_concurrent_futures/executor.py b/Lib/test/test_concurrent_futures/executor.py
index 57b77bf053adbfd..b541a2873894c79 100644
--- a/Lib/test/test_concurrent_futures/executor.py
+++ b/Lib/test/test_concurrent_futures/executor.py
@@ -102,7 +102,10 @@ def test_map_exception(self):
         )
 
         frames = map(itemgetter(0), traceback.walk_tb(exception.__traceback__))
+
+        # skip current frame
         next(frames)
+
         self.assertFalse(
             [
                 (var, val)

From fb0c5220be1a78e64b5e57484600d67b02ecf92e Mon Sep 17 00:00:00 2001
From: ebonnal <bonnal.enzo.dev@gmail.com>
Date: Wed, 23 Apr 2025 13:13:16 +0100
Subject: [PATCH 39/41] test_map_exception: improve readability

---
 Lib/test/test_concurrent_futures/executor.py | 25 ++++++++++----------
 1 file changed, 13 insertions(+), 12 deletions(-)

diff --git a/Lib/test/test_concurrent_futures/executor.py b/Lib/test/test_concurrent_futures/executor.py
index b541a2873894c79..0af0879e3ff0636 100644
--- a/Lib/test/test_concurrent_futures/executor.py
+++ b/Lib/test/test_concurrent_futures/executor.py
@@ -5,7 +5,7 @@
 import traceback
 import weakref
 from concurrent import futures
-from operator import add, itemgetter
+from operator import add
 from test import support
 from test.support import Py_GIL_DISABLED, warnings_helper
 
@@ -85,15 +85,15 @@ def test_map_exception(self):
 
         exception = None
         try:
-            next(i)
+            i.__next__()
         except Exception as e:
             exception = e
         self.assertTrue(
             isinstance(exception, ZeroDivisionError),
-            msg="next should raise a ZeroDivisionError",
+            msg="should raise a ZeroDivisionError",
         )
 
-        # free-threading builds need this pause on Ubuntu (ARM) and Windows
+        # pause needed for free-threading builds on Ubuntu (ARM) and Windows
         time.sleep(1)
 
         self.assertFalse(
@@ -101,20 +101,21 @@ def test_map_exception(self):
             msg="the exception should not have any referrers",
         )
 
-        frames = map(itemgetter(0), traceback.walk_tb(exception.__traceback__))
-
-        # skip current frame
-        next(frames)
-
         self.assertFalse(
             [
                 (var, val)
-                for frame in frames
+                # go through the frames of the exception's traceback
+                for frame, _ in traceback.walk_tb(exception.__traceback__)
+                # skipping the current frame
+                if frame is not exception.__traceback__.tb_frame
+                # go through the locals captured in that frame
                 for var, val in frame.f_locals.items()
+                # check if one of them is an exception
                 if isinstance(val, Exception)
-                and frame in map(itemgetter(0), traceback.walk_tb(val.__traceback__))
+                # check if it is captured in its own traceback
+                and frame is val.__traceback__.tb_frame
             ],
-            msg=f"the exception's traceback should not contain an exception that captures itself in its own traceback",
+            msg=f"the exception's traceback should not contain an exception captured in its own traceback",
         )
         self.assertEqual(next(i), (1, 0))
         self.assertRaises(StopIteration, next, i)

From e0a031d1b9ba3726193bc963c5afcce9c263822f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C5=81ukasz=20Langa?= <lukasz@langa.pl>
Date: Wed, 21 Oct 2026 03:30:27 +0200
Subject: [PATCH 40/41] Fix CI: break exception ref cycle in
 _MapResultIterator.__next__ (gh-74028)

Hold exc across 'raise exc' keeps the frame in the exception's referrers via
its traceback; clear it in a finally like the interpreter.py fix so the
 strengthened test_map_exception passes for all pool types.

Co-authored-by: Muse Code (Meta Muse Spark)
---
 Lib/concurrent/futures/_base.py | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/Lib/concurrent/futures/_base.py b/Lib/concurrent/futures/_base.py
index e728b8e0a91f744..505723b1e44dc5f 100644
--- a/Lib/concurrent/futures/_base.py
+++ b/Lib/concurrent/futures/_base.py
@@ -723,7 +723,11 @@ def __iter__(self):
     def __next__(self):
         value, exc = next(self.gen)
         if exc is not None:
-            raise exc
+            try:
+                raise exc
+            finally:
+                # avoid a ref cycle where exc is captured in its traceback
+                exc = None
         return value
 
     def close(self):

From 6c8f6d6bd8d30ea3bf81b1d0e3d30be9452a2f45 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C5=81ukasz=20Langa?= <lukasz@langa.pl>
Date: Wed, 21 Oct 2026 20:10:50 +0200
Subject: [PATCH 41/41] test_map_exception: wait for transient referrers
 instead of sleep(1)

The thread that completed the future can still hold the exception (via the future) when the main thread wakes up. Poll with a deadline instead of sleeping a fixed second so the test stays fast normally and robust under load, especially on free-threaded builds.

Co-authored-by: Muse Code (Meta Muse Spark)
---
 Lib/test/test_concurrent_futures/executor.py | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/Lib/test/test_concurrent_futures/executor.py b/Lib/test/test_concurrent_futures/executor.py
index 0af0879e3ff0636..812db1116b3da3b 100644
--- a/Lib/test/test_concurrent_futures/executor.py
+++ b/Lib/test/test_concurrent_futures/executor.py
@@ -93,8 +93,11 @@ def test_map_exception(self):
             msg="should raise a ZeroDivisionError",
         )
 
-        # pause needed for free-threading builds on Ubuntu (ARM) and Windows
-        time.sleep(1)
+        # Wait for the completing thread to release its transient reference
+        # to the exception; do not keep the referrers list alive in the loop.
+        for _ in support.sleeping_retry(support.SHORT_TIMEOUT, error=False):
+            if not gc.get_referrers(exception):
+                break
 
         self.assertFalse(
             gc.get_referrers(exception),