aio-libs / multidict / 37457449159

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Move _md_reader_exit() out of line (#1700)

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## What do these changes do?

Marks `_md_reader_exit()` `NOINLINE`. It ends every lock-free read on FT
builds and carries the rarely taken drain of retired tables; inlined
into each lookup it costs more than the call. Out of line, FT lookups
get up to 10 Ir cheaper. GIL builds do not have this function, and their
code is unchanged.

## Are there changes in behavior for the user?

No.

## Is it a substantial burden for the maintainers to support this?

No.

## Related issue number

N/A

## Checklist

- [x] I think the code is well written
- [ ] Unit tests for the changes exist (N/A, no behavior change)
- [x] Documentation reflects the changes (N/A)
- [ ] If you provide code modification, please add yourself to
`CONTRIBUTORS.txt` (N/A)
- [x] Add a new news fragment into the `CHANGES/` folder
- [x] `make doc-spelling` passes and any new technical words are added
to `docs/spelling_wordlist.txt`

Drafted with Claude Code (Claude Opus 5.5); reviewed by @asvetlov.

<details>
<summary>Agent run details (optional, for reviewers)</summary>

`benchmarks/callgrind_driver.py --include-multidict-only`,
`PYTHONHASHSEED=0`, base 2db70d6b vs this branch, equal-length tree and
venv paths, GCC 15. Every row not listed moved by 0 Ir; 3.14.7 is
byte-identical. A base-to-base control on a second tree was identical.

| build | impl | operation | Ir/op delta |
| --- | --- | --- | --- |
| 3.14.7t | MultiDict | getitem_hit | -2 (-1.27%) |
| 3.14.7t | MultiDict | get_miss | -2 (-0.56%) |
| 3.14.7t | MultiDict | contains_hit | -4 (-2.74%) |
| 3.14.7t | MultiDict | getitem_istr | +5 (+0.61%) |
| 3.14.7t | CIMultiDict | getitem_hit | -8 (-3.15%) |
| 3.14.7t | CIMultiDict | get_miss | -2 (-0.54%) |
| 3.14.7t | CIMultiDict | contains_hit | -2 (-0.95%) |
| 3.14.7t | CIMultiDict | pop | -3 (-0.55%) |
| 3.14.7t | CIMultiDict | getitem_istr | -10 (-4.77%) |

`.text` on 3.14.7t: 249936 -> 250256 (+320 ... (continued)

793 of 1586 branches covered (50.0%)

Branch coverage included in aggregate %.

9353 of 10217 relevant lines covered (91.54%)

1.83 hits per line