https://github.com/python/cpython/commit/7738d7c1d4464847d648be4b682fe5f734d87537 commit: 7738d7c1d4464847d648be4b682fe5f734d87537 branch: 3.15 author: Miss Islington (bot) <[email protected]> committer: hugovk <[email protected]> date: 2026-09-07T15:34:16+03:00 summary:
[3.15] gh-156512: Fix asyncio calling connection_lost() twice from resume_writing() (GH-156657) (#157031) Co-authored-by: Timofei Ivankov <[email protected]> files: A Misc/NEWS.d/next/Library/2026-08-30-13-25-53.gh-issue-156512.tVTOIV.rst M Lib/asyncio/selector_events.py M Lib/test/test_asyncio/test_selector_events.py diff --git a/Lib/asyncio/selector_events.py b/Lib/asyncio/selector_events.py index 54e9564aa1f2b3e..326d64025f36857 100644 --- a/Lib/asyncio/selector_events.py +++ b/Lib/asyncio/selector_events.py @@ -1124,7 +1124,9 @@ def _write_sendmsg(self): self._loop._remove_writer(self._sock_fd) if self._empty_waiter is not None: self._empty_waiter.set_result(None) - if self._closing: + # gh-156512: don't let _call_connection_lost be called twice + if self._closing and not self._conn_lost: + self._conn_lost += 1 self._call_connection_lost(None) elif self._eof: self._sock.shutdown(socket.SHUT_WR) @@ -1170,7 +1172,9 @@ def _write_send(self): self._loop._remove_writer(self._sock_fd) if self._empty_waiter is not None: self._empty_waiter.set_result(None) - if self._closing: + # gh-156512: don't let _call_connection_lost be called twice + if self._closing and not self._conn_lost: + self._conn_lost += 1 self._call_connection_lost(None) elif self._eof: self._sock.shutdown(socket.SHUT_WR) diff --git a/Lib/test/test_asyncio/test_selector_events.py b/Lib/test/test_asyncio/test_selector_events.py index 4bb5d4fb816a9a6..27b3af888b74385 100644 --- a/Lib/test/test_asyncio/test_selector_events.py +++ b/Lib/test/test_asyncio/test_selector_events.py @@ -1122,6 +1122,49 @@ def _resume_writing(): self.assertEqual(transport.get_write_buffer_size(), 0) self.assertTrue(self.protocol.connection_lost.called) + def test_write_ready_resume_writing_closes(self): + # gh-156512: closing from resume_writing() must not lose the connection twice + self.sock.send.return_value = 2 + + def _resume_writing(): + transport.close() + + self.protocol.resume_writing.side_effect = _resume_writing + self.loop.call_exception_handler = mock.Mock() + + transport = self.socket_transport() + transport.set_write_buffer_limits(high=1, low=0) + transport.write(b'data') + + self.loop.writers[7]._run() + test_utils.run_briefly(self.loop) + + self.assertEqual(self.protocol.connection_lost.call_count, 1) + self.loop.call_exception_handler.assert_not_called() + + @unittest.skipUnless(selector_events._HAS_SENDMSG, 'no sendmsg') + def test_write_sendmsg_resume_writing_closes(self): + # gh-156512: same as above, for the sendmsg write path + self.sock.send.return_value = 2 + self.sock.sendmsg.return_value = 2 + + def _resume_writing(): + transport.close() + + self.protocol.resume_writing.side_effect = _resume_writing + self.loop.call_exception_handler = mock.Mock() + + transport = self.socket_transport(sendmsg=True) + transport.set_write_buffer_limits(high=1, low=0) + transport.write(b'data') + + self.loop.writers[7]._run() + test_utils.run_briefly(self.loop) + + self.assertEqual(self.protocol.connection_lost.call_count, 1) + self.loop.call_exception_handler.assert_not_called() + + class SelectorSocketTransportBufferedProtocolTests(test_utils.TestCase): def setUp(self): diff --git a/Misc/NEWS.d/next/Library/2026-08-30-13-25-53.gh-issue-156512.tVTOIV.rst b/Misc/NEWS.d/next/Library/2026-08-30-13-25-53.gh-issue-156512.tVTOIV.rst new file mode 100644 index 000000000000000..16d6b7bdeae9859 --- /dev/null +++ b/Misc/NEWS.d/next/Library/2026-08-30-13-25-53.gh-issue-156512.tVTOIV.rst @@ -0,0 +1,2 @@ +Fix :mod:`asyncio` losing a connection twice when ``resume_writing()`` +closes the transport. _______________________________________________ Python-checkins mailing list -- [email protected] To unsubscribe send an email to [email protected] https://mail.python.org/mailman3//lists/python-checkins.python.org Member address: [email protected]
