[3.12] gh-109832: concurrent.futures test_deadlock restores sys.stderr (GH-109887) (#109892)

gh-109832: concurrent.futures test_deadlock restores sys.stderr (GH-109887)

test_error_at_task_unpickle() and
test_error_during_result_unpickle_in_result_handler() now restore
sys.stderr which is overriden by _raise_error_ignore_stderr().
(cherry picked from commit 2897142d2ec0930a8991af964c798b68fb6dcadd)

Co-authored-by: Victor Stinner <vstinner@python.org>

1 files changed, 6 insertions, 0 deletions

diff --git a/Lib/test/test_concurrent_futures/test_deadlock.py b/Lib/test/test_concurrent_futures/test_deadlock.py
index 2f08bf8..7ede95d 100644
--- a/Lib/test/test_concurrent_futures/test_deadlock.py
+++ b/Lib/test/test_concurrent_futures/test_deadlock.py
@@ -145,6 +145,9 @@ class ExecutorDeadlockTest:
         self._check_crash(BrokenProcessPool, id, ExitAtUnpickle())
 
     def test_error_at_task_unpickle(self):
+        # gh-109832: Restore stderr overriden by _raise_error_ignore_stderr()
+        self.addCleanup(setattr, sys, 'stderr', sys.stderr)
+
         # Check problem occurring while unpickling a task on workers
         self._check_crash(BrokenProcessPool, id, ErrorAtUnpickle())
 
@@ -180,6 +183,9 @@ class ExecutorDeadlockTest:
         self._check_crash(PicklingError, _return_instance, ErrorAtPickle)
 
     def test_error_during_result_unpickle_in_result_handler(self):
+        # gh-109832: Restore stderr overriden by _raise_error_ignore_stderr()
+        self.addCleanup(setattr, sys, 'stderr', sys.stderr)
+
         # Check problem occurring while unpickling a task in
         # the result_handler thread
         self._check_crash(BrokenProcessPool,