asyncio subprocess spawn does not record the awaiting task

Bug report

Bug description:

The internal subprocess pipe-connect task registers no awaited_by edge

Repro:

import asyncio, sys

async def main():
    spawn = asyncio.create_task(
        asyncio.create_subprocess_exec(sys.executable, '-c', 'pass',
                                       stdin=asyncio.subprocess.PIPE),
        name='spawn')

    await asyncio.sleep(0)
    await asyncio.sleep(0)

    for t in asyncio.all_tasks() - {asyncio.current_task()}:
        asyncio.print_call_graph(t)

    proc = await spawn
    await proc.wait()

asyncio.run(main())

Actual:

* Task(name='spawn', id=0x103e00b90)
  + Call stack:
  |   File '/Users/timofeiivankov/cpython/Lib/asyncio/unix_events.py', line 211, in async _UnixSelectorEventLoop._make_subprocess_transport()
  |   File '/Users/timofeiivankov/cpython/Lib/asyncio/base_events.py', line 1839, in async BaseEventLoop.subprocess_exec()
  |   File '/Users/timofeiivankov/cpython/Lib/asyncio/subprocess.py', line 249, in async create_subprocess_exec()
* Task(name='Task-2', id=0x103b7d0a0)
  + Call stack:
  |   File '/Users/timofeiivankov/cpython/Lib/asyncio/base_events.py', line 1753, in async BaseEventLoop.connect_write_pipe()
  |   File '/Users/timofeiivankov/cpython/Lib/asyncio/base_subprocess.py', line 188, in async BaseSubprocessTransport._connect_pipes()

Expected:

* Task(name='spawn', id=0x105620b90)
  + Call stack:
  |   File '/Users/timofeiivankov/cpython/Lib/asyncio/unix_events.py', line 211, in async _UnixSelectorEventLoop._make_subprocess_transport()
  |   File '/Users/timofeiivankov/cpython/Lib/asyncio/base_events.py', line 1839, in async BaseEventLoop.subprocess_exec()
  |   File '/Users/timofeiivankov/cpython/Lib/asyncio/subprocess.py', line 249, in async create_subprocess_exec()
* Task(name='Task-2', id=0x10539d0a0)
  + Call stack:
  |   File '/Users/timofeiivankov/cpython/Lib/asyncio/base_events.py', line 1753, in async BaseEventLoop.connect_write_pipe()
  |   File '/Users/timofeiivankov/cpython/Lib/asyncio/base_subprocess.py', line 194, in async BaseSubprocessTransport._connect_pipes()
  + Awaited by:
    * Task(name='spawn', id=0x105620b90)
      + Call stack:
      |   File '/Users/timofeiivankov/cpython/Lib/asyncio/unix_events.py', line 211, in async _UnixSelectorEventLoop._make_subprocess_transport()
      |   File '/Users/timofeiivankov/cpython/Lib/asyncio/base_events.py', line 1839, in async BaseEventLoop.subprocess_exec()
      |   File '/Users/timofeiivankov/cpython/Lib/asyncio/subprocess.py', line 249, in async create_subprocess_exec()

Proposed fix: register the edge in BaseSubprocessTransport.__init__ and discard it in doe callback

I have a fix ready for that

CPython versions tested on:

CPython main branch

Operating systems tested on:

macOS

Bắt đầu trong Lib/asyncio/base_subprocess.py tại BaseSubprocessTransport.init và kiểm tra đường dẫn kết nối pipe của subprocess được hiển thị trong traceback. Chạy bản tái hiện asyncio được cung cấp và xác nhận rằng tác vụ kết nối pipe nội bộ báo cáo một cạnh “Awaited by” cho tác vụ spawn, sau đó xác minh rằng cạnh này bị callback hoàn tất loại bỏ.