https://github.com/python/cpython/commit/0ea2971c6eeaaed3429b5b655b77afe24fa798a8
commit: 0ea2971c6eeaaed3429b5b655b77afe24fa798a8
branch: main
author: Thomas Grainger <[email protected]>
committer: kumaraditya303 <[email protected]>
date: 2026-09-05T10:52:14Z
summary:
gh-127057: reschedule proactor datagram read loop after ConnectionResetError
(#156726)
files:
A Misc/NEWS.d/next/Library/2026-08-31-00-00-00.gh-issue-127057.N9yg62.rst
M Lib/asyncio/proactor_events.py
M Lib/test/test_asyncio/test_events.py
diff --git a/Lib/asyncio/proactor_events.py b/Lib/asyncio/proactor_events.py
index f18a7fe58558155..7adb09f3fce5de7 100644
--- a/Lib/asyncio/proactor_events.py
+++ b/Lib/asyncio/proactor_events.py
@@ -571,6 +571,15 @@ def _loop_reading(self, fut=None):
else:
self._read_fut = self._loop._proactor.recvfrom(self._sock,
self.max_size)
+ except ConnectionResetError as exc:
+ # WSARecvFrom() reports a stale ICMP port unreachable
+ # notification as a synchronous ConnectionResetError when the
+ # same socket was used to send to an address that is not
+ # listening. This is transient, so reschedule the read loop
+ # instead of leaving it dead.
+ self._protocol.error_received(exc)
+ if not self._closing:
+ self._loop.call_soon(self._loop_reading)
except OSError as exc:
self._protocol.error_received(exc)
except exceptions.CancelledError:
diff --git a/Lib/test/test_asyncio/test_events.py
b/Lib/test/test_asyncio/test_events.py
index db316fae090280a..06f538bceea1672 100644
--- a/Lib/test/test_asyncio/test_events.py
+++ b/Lib/test/test_asyncio/test_events.py
@@ -1583,6 +1583,60 @@ def create_socket():
transport_1.close()
transport_2.close()
+ def test_datagram_recvfrom_connection_reset_recovers(self):
+ # gh-127057: a UDP socket that sent a datagram to an address that
+ # wasn't listening can raise ConnectionResetError on a later
+ # receive. The transport must keep working afterwards.
+ loop = self.loop
+
+ class Protocol(asyncio.DatagramProtocol):
+ def connection_made(self, transport):
+ self.transport = transport
+ self.errors = []
+ self.received = []
+ self.datagram_received_event = loop.create_future()
+
+ def error_received(self, exc):
+ self.errors.append(exc)
+
+ def datagram_received(self, data, addr):
+ self.received.append(data)
+ if not self.datagram_received_event.done():
+ self.datagram_received_event.set_result(None)
+
+ sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+ sock.setblocking(False)
+ sock.bind(('127.0.0.1', 0))
+ addr = sock.getsockname()
+
+ # Bind and immediately close a second socket to get an address
+ # that is guaranteed not to be listening.
+ closed = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+ closed.bind(('127.0.0.1', 0))
+ closed_addr = closed.getsockname()
+ closed.close()
+
+ # Trigger the error before the socket is wrapped in a transport,
+ # so that the first read raises synchronously.
+ sock.sendto(b'x', closed_addr)
+
+ transport, protocol = loop.run_until_complete(
+ loop.create_datagram_endpoint(Protocol, sock=sock))
+
+ transport.sendto(b'ping', addr)
+ loop.run_until_complete(asyncio.wait_for(
+ protocol.datagram_received_event, support.SHORT_TIMEOUT))
+ self.assertEqual(protocol.received, [b'ping'])
+
+ if sys.platform == 'win32':
+ # Other platforms don't report ICMP errors on an
+ # unconnected UDP socket.
+ self.assertEqual(len(protocol.errors), 1)
+ self.assertIsInstance(protocol.errors[0], ConnectionResetError)
+
+ transport.close()
+ test_utils.run_briefly(loop)
+
def test_internal_fds(self):
loop = self.create_event_loop()
if not isinstance(loop, selector_events.BaseSelectorEventLoop):
diff --git
a/Misc/NEWS.d/next/Library/2026-08-31-00-00-00.gh-issue-127057.N9yg62.rst
b/Misc/NEWS.d/next/Library/2026-08-31-00-00-00.gh-issue-127057.N9yg62.rst
new file mode 100644
index 000000000000000..f47da0453249cad
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2026-08-31-00-00-00.gh-issue-127057.N9yg62.rst
@@ -0,0 +1,3 @@
+Fix :class:`asyncio.ProactorEventLoop` UDP transports so that a
+:exc:`ConnectionResetError` raised by ``WSARecvFrom`` no longer stops the
+read loop.
_______________________________________________
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]
