gh-92841: Fix asyncio's RuntimeError: Event loop is closed

[arhadthedev]

Both asyncio.selector_events._SelectorTransport and asyncio.proactor_events._ProactorBasePipeTransport check if an associated socket is left unclosed and emit a warning on a positive answer.

However, further behavior differs. While _SelectorTransport closes the socket:

def __del__(self, _warn=warnings.warn):
    if self._sock is not None:
        _warn(f"unclosed transport {self!r}", ResourceWarning, source=self)
        self._sock.close()

the _ProactorBasePipeTransport attempts to close itself leaving the socked leaked:

def __del__(self, _warn=warnings.warn):
    if self._sock is not None:
        _warn(f"unclosed transport {self!r}", ResourceWarning, source=self)
        self.close()

It looks like there was no plan to close the transport itself causing <already closed parent loop>.call_soon().

The deleters were introduced by 978a9af with no explanatory comment about the implementation difference.

Fixes (no autoclose) gh-92841, gh-91233, and gh-83413. Probably fixes (no autoclose) gh-81562.

[arhadthedev]

Note that the NEWS entry uses socket activity instead of pipe activity because _ProactorBasePipeTransport affects sockets via its inheritance chain:

classDiagram
_ProactorBasePipeTransport <|-- _ProactorReadPipeTransport
_ProactorBasePipeTransport <|-- _ProactorBaseWritePipeTransport
_ProactorBasePipeTransport <|-- _ProactorDatagramTransport
_ProactorReadPipeTransport <|-- _ProactorDuplexPipeTransport
_ProactorBaseWritePipeTransport <|-- _ProactorDuplexPipeTransport
_ProactorReadPipeTransport <|-- _ProactorSocketTransport
_ProactorBaseWritePipeTransport <|-- _ProactorSocketTransport

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[miss-islington]

Thanks @arhadthedev for the PR, and @zooba for merging it 🌮🎉.. I'm working now to backport this PR to: 3.10.
🐍🍒⛏🤖

[miss-islington]

Thanks @arhadthedev for the PR, and @zooba for merging it 🌮🎉.. I'm working now to backport this PR to: 3.11.
🐍🍒⛏🤖

[bedevere-bot]

GH-92904 is a backport of this pull request to the 3.10 branch.

[bedevere-bot]

GH-92905 is a backport of this pull request to the 3.11 branch.