[PR #3733/6b0bc4ef backport][3.13] Fix connector not waiting for connections to close

[bdraco]

What do these changes do?

This PR fixes an issue where BaseConnector.close() would return immediately without waiting for connections to actually close. This is a partial backport of #3733 that includes only the bug fix without any breaking API changes.

The fix ensures that close() properly waits for all connection closures to complete by:

• Collecting all proto.closed futures from connections being closed
• Using asyncio.gather() to wait for all closures to complete
• Optimizing for Python 3.12+ by using eager task execution when available

Are there changes in behavior for the user?

No breaking changes. The close() method will now properly wait for connections to close as expected, which is the correct behavior. The method continues to return an awaitable that emits a deprecation warning if not awaited.

Note: When using the connector as a non-async context manager (deprecated pattern), the issue of not waiting for connections to close still remains. This is because __exit__ calls _close() synchronously and cannot await the connection closures. Users should use the async context manager pattern (async with) instead. We cannot remove the sync context manager in 3.x as that would be a breaking change.

Related issue number

Partial backport of #3733
fixes #1925 fixes #3736

Checklist

• I think the code is well written
• Unit tests for the changes exist
• Documentation reflects the changes
• If you provide code modification, please add yourself to CONTRIBUTORS.txt
• Add a new news fragment into the CHANGES/ folde

[codspeed-hq]

CodSpeed Performance Report

Merging #11074 will not alter performance

_{Comparing backport_close_fix (9998fb1) with 3.13 (05d39fe)}

Summary

✅ 59 untouched benchmarks

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 98.24%. Comparing base (05d39fe) to head (9998fb1).
⚠️ Report is 224 commits behind head on 3.13.

Additional details and impacted files

@@           Coverage Diff           @@
##             3.13   #11074   +/-   ##
=======================================
  Coverage   98.24%   98.24%           
=======================================
  Files         130      130           
  Lines       41612    41664   +52     
  Branches     2286     2291    +5     
=======================================
+ Hits        40880    40933   +53     
  Misses        557      557           
+ Partials      175      174    -1     

Flag	Coverage Δ
CI-GHA	98.13% <98.82%> (+<0.01%)	⬆️
OS-Linux	97.87% <98.82%> (-0.01%)	⬇️
OS-Windows	95.47% <98.82%> (+0.01%)	⬆️
OS-macOS	97.08% <98.82%> (-0.01%)	⬇️
Py-3.10.11	96.97% <97.64%> (+<0.01%)	⬆️
Py-3.10.17	97.47% <97.64%> (-0.02%)	⬇️
Py-3.11.12	97.56% <97.64%> (+0.02%)	⬆️
Py-3.11.9	97.05% <97.64%> (-0.01%)	⬇️
Py-3.12.10	97.92% <97.64%> (-0.01%)	⬇️
Py-3.13.3	97.92% <97.64%> (+0.01%)	⬆️
Py-3.9.13	96.86% <97.64%> (+<0.01%)	⬆️
Py-3.9.22	97.37% <97.64%> (-0.02%)	⬇️
Py-pypy7.3.16	83.17% <97.64%> (-1.57%)	⬇️
VM-macos	97.08% <98.82%> (-0.01%)	⬇️
VM-ubuntu	97.87% <98.82%> (-0.01%)	⬇️
VM-windows	95.47% <98.82%> (+0.01%)	⬆️

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[patchback]

Backport to 3.11: 💚 backport PR created

✅ Backport PR branch: patchback/backports/3.11/e550c78a943be34ffd01b58acbcc0f06485bbbd9/pr-11074

Backported as #11076

🤖 @patchback
I'm built with octomachinery and
my source is open — https://github.com/sanitizers/patchback-github-app.

[patchback]

Backport to 3.12: 💚 backport PR created

✅ Backport PR branch: patchback/backports/3.12/e550c78a943be34ffd01b58acbcc0f06485bbbd9/pr-11074

Backported as #11077

🤖 @patchback
I'm built with octomachinery and
my source is open — https://github.com/sanitizers/patchback-github-app.

[God-damnit-all]

I recommend editing the release notes for v3.13.0 to mention this bugfix, since it's fairly important.

[Dreamsorcerer]

Hmm, where did that change fragment go? It wasn't in the branch during release..

[Dreamsorcerer]

Oh, no, this is already released previously:
faa742b

[God-damnit-all]

Oh, no, this is already released previously: faa742b

Strange, it's in the least of commit differences between 3.12.15 and 3.13.0: v3.12.15...v3.13.0