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[3.14] gh-115999: Note Python 3.14 free-threaded changes in What's New (gh-131285) #133824

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May 10, 2025
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[3.14] gh-115999: Note Python 3.14 free-threaded changes in What's New (gh-131285) #133824

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22 changes: 22 additions & 0 deletions Doc/whatsnew/3.14.rst
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Expand Up @@ -88,6 +88,7 @@ and improvements in user-friendliness and correctness.
* :ref:`PEP 758: Allow except and except* expressions without parentheses <whatsnew314-pep758>`
* :ref:`PEP 761: Discontinuation of PGP signatures <whatsnew314-pep761>`
* :ref:`PEP 765: Disallow return/break/continue that exit a finally block <whatsnew314-pep765>`
* :ref:`Free-threaded mode improvements <whatsnew314-free-threaded-cpython>`
* :ref:`PEP 768: Safe external debugger interface for CPython <whatsnew314-pep768>`
* :ref:`PEP 784: Adding Zstandard to the standard library <whatsnew314-pep784>`
* :ref:`A new type of interpreter <whatsnew314-tail-call>`
Expand Down Expand Up @@ -794,6 +795,27 @@ For further information on how to build Python, see
(Contributed by Ken Jin in :gh:`128563`, with ideas on how to implement this
in CPython by Mark Shannon, Garrett Gu, Haoran Xu, and Josh Haberman.)

.. _whatsnew314-free-threaded-cpython:

Free-threaded mode
------------------

Free-threaded mode (:pep:`703`), initially added in 3.13, has been significantly improved.
The implementation described in PEP 703 was finished, including C API changes,
and temporary workarounds in the interpreter were replaced with more permanent solutions.
The specializing adaptive interpreter (:pep:`659`) is now enabled in free-threaded mode,
which along with many other optimizations greatly improves its performance.
The performance penalty on single-threaded code in free-threaded mode is now roughly 5-10%,
depending on platform and C compiler used.

This work was done by many contributors: Sam Gross, Matt Page, Neil Schemenauer,
Thomas Wouters, Donghee Na, Kirill Podoprigora, Ken Jin, Itamar Oren,
Brett Simmers, Dino Viehland, Nathan Goldbaum, Ralf Gommers, Lysandros Nikolaou,
Kumar Aditya, Edgar Margffoy, and many others.

Some of these contributors are employed by Meta, which has continued to provide
significant engineering resources to support this project.


.. _whatsnew314-pyrepl-highlighting:

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