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gh-152633: Fix outdated default compresslevel in gzip docs - #152634

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Jaden-Varkey wants to merge 2 commits into
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Jaden-Varkey:fix-gzip-default-compresslevel-docs
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Jaden-Varkey wants to merge 2 commits into
python:mainfrom
Jaden-Varkey:fix-gzip-default-compresslevel-docs

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@Jaden-Varkey

@Jaden-Varkey Jaden-Varkey commented Jun 29, 2026 •

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The default compresslevel for gzip.open(), the GzipFile constructor, and gzip.compress() is COMPRESS_LEVEL_TRADEOFF (6). The signatures and the "Changed in version" notes in Doc/library/gzip.rst already reflect this (it says "the default compression level was reduced to 6, down from 9").
However, a few places still state the default is 9 and should be updated:-

  1. the gzip.open() docstring in Lib/gzip.py
  2. the GzipFile.init docstring in Lib/gzip.py
  3. the GzipFile paragraph in Doc/library/gzip.rst

The default compression level for gzip.open(), the GzipFile constructor
and gzip.compress() was lowered from 9 to 6 (it now uses
_COMPRESS_LEVEL_TRADEOFF), and the signatures and versionchanged notes
were updated accordingly. A couple of docstrings and one paragraph in
the library docs still said the default was 9, which was misleading.
Update them to match the actual default of 6.
@python-cla-bot

python-cla-bot Bot commented Jun 29, 2026 •

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All commit authors signed the Contributor License Agreement.

CLA signed

@bedevere-app

bedevere-app Bot commented Jun 29, 2026

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Most changes to Python require a NEWS entry. Add one using the blurb_it web app or the blurb command-line tool.

If this change has little impact on Python users, wait for a maintainer to apply the skip news label instead.

@read-the-docs-community

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Documentation build overview

📚 cpython-previews | 🛠️ Build #33363117 | 📁 Comparing b6d2609 against main (edcc07d)

  🔍 Preview build  

1 file changed
± library/gzip.html

@Jaden-Varkey

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This is a documentation-only change (two docstrings plus one paragraph in gzip.rst), so it shouldn't need a Misc/NEWS entry; could a skip news label be added? Appreciate it!

@Jaden-Varkey

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Gentle ping — this is a small docs-only fix and all checks are green. Would a core dev be able to take a look when you have a moment? Happy to make any changes. Thanks!

@StanFromIreland

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Sorry we missed this, it was fixed in 49aed47.

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3 participants