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GeezerVison is showing github.com — [3.13] gh-98820: Fix quadratic time in csv.Sniffer for quoted fields (GH-154867) by miss-islington · Pull Request #155118 · python/cpython

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@miss-islington

@miss-islington miss-islington commented Aug 3, 2026 •
edited by bedevere-app Bot
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The regular expressions which look for a quoted field matched its body
lazily, so a closing quote which was not followed by a delimiter was
retried with every following quote, to the end of the sample. Match
the body possessively instead: it ends at the first quote which is not
doubled, as it does for a reader.
(cherry picked from commit 476fb09)

Co-authored-by: Serhiy Storchaka [email protected]
Co-authored-by: Claude Opus 5 (1M context) [email protected]

  • Issue: csv.Sniffer().sniff() Hangs on Single-Column Data #98820

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@serhiy-storchaka @claude @miss-islington
[3.15] pythongh-98820: Fix quadratic time in csv.Sniffer for quoted f…
ae6b77b 
…ields (pythonGH-154867)

The regular expressions which look for a quoted field matched its body
lazily, so a closing quote which was not followed by a delimiter was
retried with every following quote, to the end of the sample.  Match
the body possessively instead: it ends at the first quote which is not
doubled, as it does for a reader.
(cherry picked from commit 476fb09)

Co-authored-by: Serhiy Storchaka <[email protected]>
Co-authored-by: Claude Opus 5 (1M context) <[email protected]>
This was referenced Aug 3, 2026
csv.Sniffer().sniff() Hangs on Single-Column Data #98820
Closed
[3.15] gh-98820: Fix quadratic time in csv.Sniffer for quoted fields #154867
Merged
@bedevere-app bedevere-app Bot added type-security A security issue awaiting review labels Aug 3, 2026
@Yhg1s
Yhg1s merged commit b30c7fa into python:3.13 Aug 4, 2026
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@bedevere-app bedevere-app Bot removed the awaiting review label Aug 4, 2026
@miss-islington
miss-islington deleted the backport-476fb09-3.13 branch August 4, 2026 09:03
@serhiy-storchaka serhiy-storchaka added needs backport to 3.10 needs backport to 3.11 only security fixes needs backport to 3.12 only security fixes labels Aug 4, 2026
@miss-islington-app

miss-islington-app Bot commented Aug 4, 2026

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Thanks @miss-islington for the PR, and @Yhg1s for merging it 🌮🎉.. I'm working now to backport this PR to: 3.10.
🐍🍒⛏🤖
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@miss-islington-app

miss-islington-app Bot commented Aug 4, 2026

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Thanks @miss-islington for the PR, and @Yhg1s for merging it 🌮🎉.. I'm working now to backport this PR to: 3.12.
🐍🍒⛏🤖
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@miss-islington-app

miss-islington-app Bot commented Aug 4, 2026

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Thanks @miss-islington for the PR, and @Yhg1s for merging it 🌮🎉.. I'm working now to backport this PR to: 3.11.
🐍🍒⛏🤖
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@miss-islington-app

miss-islington-app Bot commented Aug 4, 2026

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Sorry, @miss-islington and @Yhg1s, I could not cleanly backport this to 3.10 due to a conflict.
Please backport using cherry_picker on command line.

cherry_picker b30c7fa9edd921a118f286e9f90f560777fa693b 3.10
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@miss-islington-app miss-islington-app Bot assigned Yhg1s Aug 4, 2026
@miss-islington-app

miss-islington-app Bot commented Aug 4, 2026

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Sorry, @miss-islington and @Yhg1s, I could not cleanly backport this to 3.12 due to a conflict.
Please backport using cherry_picker on command line.

cherry_picker b30c7fa9edd921a118f286e9f90f560777fa693b 3.12
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@miss-islington-app

miss-islington-app Bot commented Aug 4, 2026

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Sorry, @miss-islington and @Yhg1s, I could not cleanly backport this to 3.11 due to a conflict.
Please backport using cherry_picker on command line.

cherry_picker b30c7fa9edd921a118f286e9f90f560777fa693b 3.11
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@serhiy-storchaka serhiy-storchaka added needs backport to 3.12 only security fixes and removed needs backport to 3.12 only security fixes labels Aug 4, 2026
@miss-islington-app

miss-islington-app Bot commented Aug 4, 2026

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Thanks @miss-islington for the PR, and @Yhg1s for merging it 🌮🎉.. I'm working now to backport this PR to: 3.12.
🐍🍒⛏🤖
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@miss-islington-app

miss-islington-app Bot commented Aug 4, 2026

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Sorry, @miss-islington and @Yhg1s, I could not cleanly backport this to 3.12 due to a conflict.
Please backport using cherry_picker on command line.

cherry_picker b30c7fa9edd921a118f286e9f90f560777fa693b 3.12
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@serhiy-storchaka serhiy-storchaka removed needs backport to 3.10 needs backport to 3.11 only security fixes needs backport to 3.12 only security fixes labels Aug 4, 2026
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@miss-islington @serhiy-storchaka @Yhg1s
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