gh-107219: Fix concurrent.futures terminate_broken() (GH-109244)
Fix a race condition in concurrent.futures. When a process in the
process pool was terminated abruptly (while the future was running or
pending), close the connection write end. If the call queue is
blocked on sending bytes to a worker process, closing the connection
write end interrupts the send, so the queue can be closed.
Changes:
* _ExecutorManagerThread.terminate_broken() now closes
call_queue._writer.
* multiprocessing PipeConnection.close() now interrupts
WaitForMultipleObjects() in _send_bytes() by cancelling the
overlapped operation.
(cherry picked from commit a9b1f84790)
Co-authored-by: Victor Stinner <vstinner@python.org>
2f8c80f531