[3.7] bpo-33694: Fix race condition in asyncio proactor (GH-7498) by miss-islington · Pull Request #7499 · python/cpython (original) (raw)

The cancellation of an overlapped WSARecv() has a race condition
which causes data loss because of the current implementation of
proactor in asyncio.

No longer cancel overlapped WSARecv() in _ProactorReadPipeTransport
to work around the race condition.

Remove the optimized recv_into() implementation to get simple
implementation of pause_reading() using the single _pending_data
attribute.

Move _feed_data_to_bufferred_proto() to protocols.py.

Remove set_protocol() method which became useless.
(cherry picked from commit 79790bc)

Co-authored-by: Victor Stinner vstinner@redhat.com

https://bugs.python.org/issue33694