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gh-91349: Adjust default compression level to 6 (down from 9) in gzip and tarfile #131470

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gh-91349: Adjust default compression level to 6 (down from 9) in gzip and tarfile #131470

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6 changes: 3 additions & 3 deletions Doc/library/gzip.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -26,7 +26,7 @@ Note that additional file formats which can be decompressed by the
The module defines the following items:


.. function:: open(filename, mode='rb', compresslevel=9, encoding=None, errors=None, newline=None)
.. function:: open(filename, mode='rb', compresslevel=6, encoding=None, errors=None, newline=None)

Open a gzip-compressed file in binary or text mode, returning a :term:`file
object`.
Expand Down Expand Up @@ -67,7 +67,7 @@ The module defines the following items:

.. versionadded:: 3.8

.. class:: GzipFile(filename=None, mode=None, compresslevel=9, fileobj=None, mtime=None)
.. class:: GzipFile(filename=None, mode=None, compresslevel=6, fileobj=None, mtime=None)

Constructor for the :class:`GzipFile` class, which simulates most of the
methods of a :term:`file object`, with the exception of the :meth:`~io.IOBase.truncate`
Expand Down Expand Up @@ -184,7 +184,7 @@ The module defines the following items:
attribute instead.


.. function:: compress(data, compresslevel=9, *, mtime=0)
.. function:: compress(data, compresslevel=6, *, mtime=0)

Compress the *data*, returning a :class:`bytes` object containing
the compressed data. *compresslevel* and *mtime* have the same meaning as in
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4 changes: 2 additions & 2 deletions Lib/tarfile.py
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Expand Up @@ -1911,7 +1911,7 @@ def taropen(cls, name, mode="r", fileobj=None, **kwargs):
return cls(name, mode, fileobj, **kwargs)

@classmethod
def gzopen(cls, name, mode="r", fileobj=None, compresslevel=9, **kwargs):
def gzopen(cls, name, mode="r", fileobj=None, compresslevel=6, **kwargs):
"""Open gzip compressed tar archive name for reading or writing.
Appending is not allowed.
"""
Expand Down Expand Up @@ -1944,7 +1944,7 @@ def gzopen(cls, name, mode="r", fileobj=None, compresslevel=9, **kwargs):
return t

@classmethod
def bz2open(cls, name, mode="r", fileobj=None, compresslevel=9, **kwargs):
def bz2open(cls, name, mode="r", fileobj=None, compresslevel=6, **kwargs):
"""Open bzip2 compressed tar archive name for reading or writing.
Appending is not allowed.
"""
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3 changes: 3 additions & 0 deletions Misc/NEWS.d/next/Library/2025-03-19-12-41-42.gh-issue-91349.8eTOCP.rst
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@@ -0,0 +1,3 @@
Adjust default compression level to 6 (down from 9) in gzip and tarfile.
It is the default level used by most compression tools and a better
tradeoff between speed and performance.
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