!18 Backport fixes to as_completed and map iterators (bpo-27144)

From: @zhang-liang-pengkun 
Reviewed-by: @Charlie_li 
Signed-off-by: @Charlie_li

0003-Backport-fixes-to-as_completed-and-map-iterators-bpo.patch

@@ -0,0 +1,121 @@
+From 28fa404639a702c32a18a1a411409f1aab8ab464 Mon Sep 17 00:00:00 2001
+From: Lisandro Dalcin <dalcinl@gmail.com>
+Date: Wed, 29 Nov 2017 22:40:47 +0300
+Subject: [PATCH] Backport fixes to as_completed and map iterators (bpo-27144)
+ (#66)
+
+Python issues:
+
++ python/cpython#1560
++ python/cpython#3270
++ python/cpython#3830
+---
+ concurrent/futures/_base.py | 53 ++++++++++++++++++++++++++++++-------
+ 1 file changed, 43 insertions(+), 10 deletions(-)
+
+diff --git a/concurrent/futures/_base.py b/concurrent/futures/_base.py
+index 401e488..510ffa5 100644
+--- a/concurrent/futures/_base.py
++++ b/concurrent/futures/_base.py
+@@ -172,6 +172,29 @@ def _create_and_install_waiters(fs, return_when):
+ 
+     return waiter
+ 
++
++def _yield_finished_futures(fs, waiter, ref_collect):
++    """
++    Iterate on the list *fs*, yielding finished futures one by one in
++    reverse order.
++    Before yielding a future, *waiter* is removed from its waiters
++    and the future is removed from each set in the collection of sets
++    *ref_collect*.
++
++    The aim of this function is to avoid keeping stale references after
++    the future is yielded and before the iterator resumes.
++    """
++    while fs:
++        f = fs[-1]
++        for futures_set in ref_collect:
++            futures_set.remove(f)
++        with f._condition:
++            f._waiters.remove(waiter)
++        del f
++        # Careful not to keep a reference to the popped value
++        yield fs.pop()
++
++
+ def as_completed(fs, timeout=None):
+     """An iterator over the given futures that yields each as it completes.
+ 
+@@ -194,16 +217,19 @@ def as_completed(fs, timeout=None):
+         end_time = timeout + time.time()
+ 
+     fs = set(fs)
++    total_futures = len(fs)
+     with _AcquireFutures(fs):
+         finished = set(
+                 f for f in fs
+                 if f._state in [CANCELLED_AND_NOTIFIED, FINISHED])
+         pending = fs - finished
+         waiter = _create_and_install_waiters(fs, _AS_COMPLETED)
+-
++    finished = list(finished)
+     try:
+-        for future in finished:
+-            yield future
++        for f in _yield_finished_futures(finished, waiter,
++                                         ref_collect=(fs,)):
++            f = [f]
++            yield f.pop()
+ 
+         while pending:
+             if timeout is None:
+@@ -213,7 +239,7 @@ def as_completed(fs, timeout=None):
+                 if wait_timeout < 0:
+                     raise TimeoutError(
+                             '%d (of %d) futures unfinished' % (
+-                            len(pending), len(fs)))
++                            len(pending), total_futures))
+ 
+             waiter.event.wait(wait_timeout)
+ 
+@@ -222,11 +248,15 @@ def as_completed(fs, timeout=None):
+                 waiter.finished_futures = []
+                 waiter.event.clear()
+ 
+-            for future in finished:
+-                yield future
+-                pending.remove(future)
++            # reverse to keep finishing order
++            finished.reverse()
++            for f in _yield_finished_futures(finished, waiter,
++                                             ref_collect=(fs, pending)):
++                f = [f]
++                yield f.pop()
+ 
+     finally:
++        # Remove waiter from unfinished futures
+         for f in fs:
+             with f._condition:
+                 f._waiters.remove(waiter)
+@@ -603,11 +633,14 @@ class Executor(object):
+         # before the first iterator value is required.
+         def result_iterator():
+             try:
+-                for future in fs:
++                # reverse to keep finishing order
++                fs.reverse()
++                while fs:
++                    # Careful not to keep a reference to the popped future
+                     if timeout is None:
+-                        yield future.result()
++                        yield fs.pop().result()
+                     else:
+-                        yield future.result(end_time - time.time())
++                        yield fs.pop().result(end_time - time.time())
+             finally:
+                 for future in fs:
+                     future.cancel()
+-- 
+2.39.0.windows.2
+

python-futures.spec

@@ -1,12 +1,13 @@
 Name:          python-futures
 Version:       3.1.1
-Release:       7
+Release:       8
 Summary:       Backport of the concurrent.futures standard library module to Python 3.2
 License:       Python
 URL:           https://github.com/agronholm/pythonfutures
 Source0:       https://files.pythonhosted.org/packages/source/f/futures/futures-%{version}.tar.gz
 Patch01:       0001-Backport-thread_name_prefix-from-upstream-64.patch
 Patch02:       0002-Specify-python_requires-to-prevent-installation-on-P.patch
+Patch03:       0003-Backport-fixes-to-as_completed-and-map-iterators-bpo.patch
 BuildRequires: python2-devel
 BuildArch:     noarch
 
@@ -41,6 +42,9 @@ The concurrent.futures module provides a high-level interface for asynchronously
 %{python2_sitelib}/futures-*.egg-info*
 
 %changelog
+* Thu Dec 21 2023 zhangliangpengkun<zhangliangpengkun@xfusion.com> - 3.1.1-8
+- Backport fixes to as_completed and map iterators (bpo-27144) (#66)
+
 * Thu Nov 02 2023 zhangliangpengkun<zhangliangpengkun@xfusion.com> - 3.1.1-7
 - Specify python_requires to prevent installation on Python 3