There are a couple of uncompleted asyncio feature removals scheduled for 3.9 and 3.10 releases. It will be great if we either complete them or reschedule before the 3.10 feature freeze. There are two stale pull requests related to this.
Removal of @asyncio.coroutine in version 3.10 deprecated since version 3.8 Documentation: https://docs.python.org/3.10/library/asyncio-task.html#asyncio.coroutine Issue deprecating the decorator: https://bugs.python.org/issue36921 Issue for the removal: https://bugs.python.org/issue43216 There is no pull request yet, mainly because of an unclarified question regarding types.coroutine in 36921.
Prohibiting non-ThreadPoolExecutor in loop.set_default_executor Warning scheduling the prohibiting in version 3.9: https://github.com/python/cpython/blob/425434dadc30d96dc1c0c628f954f9b6f5edd... Issue: https://bugs.python.org/issue43234 Stale pull request: https://github.com/python/cpython/pull/24540
Prohibiting previously deprecated operations on asyncio.trsock.TransportSocket Warning scheduling the prohibiting in version 3.9: https://github.com/python/cpython/blob/425434dadc30d96dc1c0c628f954f9b6f5edd... Issue: https://bugs.python.org/issue43232 Stale pull request: https://github.com/python/cpython/pull/24538