https://github.com/python/cpython/commit/dda9d0011fc3d3f561ca00ac83bf7a55a6325aa9
commit: dda9d0011fc3d3f561ca00ac83bf7a55a6325aa9
branch: main
author: Hugo van Kemenade <[email protected]>
committer: hugovk <[email protected]>
date: 2025-07-20T12:56:55+03:00
summary:
gh-108362: Retarget incremental GC changes to 3.14 (#125453)
files:
M Doc/library/gc.rst
M Doc/whatsnew/3.14.rst
diff --git a/Doc/library/gc.rst b/Doc/library/gc.rst
index 7ccb0e6bdf9406..2ef5c4b35a25cc 100644
--- a/Doc/library/gc.rst
+++ b/Doc/library/gc.rst
@@ -60,7 +60,7 @@ The :mod:`gc` module provides the following functions:
The effect of calling ``gc.collect()`` while the interpreter is already
performing a collection is undefined.
- .. versionchanged:: 3.13
+ .. versionchanged:: 3.14
``generation=1`` performs an increment of collection.
@@ -83,13 +83,13 @@ The :mod:`gc` module provides the following functions:
returned. If *generation* is not ``None``, return only the objects as
follows:
* 0: All objects in the young generation
- * 1: No objects, as there is no generation 1 (as of Python 3.13)
+ * 1: No objects, as there is no generation 1 (as of Python 3.14)
* 2: All objects in the old generation
.. versionchanged:: 3.8
New *generation* parameter.
- .. versionchanged:: 3.13
+ .. versionchanged:: 3.14
Generation 1 is removed
.. audit-event:: gc.get_objects generation gc.get_objects
@@ -142,7 +142,7 @@ The :mod:`gc` module provides the following functions:
See `Garbage collector design
<https://devguide.python.org/garbage_collector>`_ for more information.
- .. versionchanged:: 3.13
+ .. versionchanged:: 3.14
*threshold2* is ignored
diff --git a/Doc/whatsnew/3.14.rst b/Doc/whatsnew/3.14.rst
index c108a94692dca7..6ddc77d8f95038 100644
--- a/Doc/whatsnew/3.14.rst
+++ b/Doc/whatsnew/3.14.rst
@@ -1058,6 +1058,30 @@ free-threaded build and false for the GIL-enabled build.
(Contributed by Neil Schemenauer and Kumar Aditya in :gh:`130010`.)
+.. _whatsnew314-incremental-gc:
+
+Incremental garbage collection
+------------------------------
+
+The cycle garbage collector is now incremental.
+This means that maximum pause times are reduced
+by an order of magnitude or more for larger heaps.
+
+There are now only two generations: young and old.
+When :func:`gc.collect` is not called directly, the
+GC is invoked a little less frequently. When invoked, it
+collects the young generation and an increment of the
+old generation, instead of collecting one or more generations.
+
+The behavior of :func:`!gc.collect` changes slightly:
+
+* ``gc.collect(1)``: Performs an increment of garbage collection,
+ rather than collecting generation 1.
+* Other calls to :func:`!gc.collect` are unchanged.
+
+(Contributed by Mark Shannon in :gh:`108362`.)
+
+
Other language changes
======================
@@ -1486,6 +1510,36 @@ functools
(Contributed by Sayandip Dutta in :gh:`125916`.)
+gc
+--
+
+The cyclic garbage collector is now incremental,
+which changes the meaning of the results of
+:meth:`~gc.get_threshold` and :meth:`~gc.set_threshold`
+as well as :meth:`~gc.get_count` and :meth:`~gc.get_stats`.
+
+* For backwards compatibility, :meth:`~gc.get_threshold` continues to return
+ a three-item tuple.
+ The first value is the threshold for young collections, as before;
+ the second value determines the rate at which the old collection is scanned
+ (the default is 10, and higher values mean that the old collection
+ is scanned more slowly).
+ The third value is meaningless and is always zero.
+
+* :meth:`~gc.set_threshold` ignores any items after the second.
+
+* :meth:`~gc.get_count` and :meth:`~gc.get_stats` continue to return
+ the same format of results.
+ The only difference is that instead of the results referring to
+ the young, aging and old generations,
+ the results refer to the young generation
+ and the aging and collecting spaces of the old generation.
+
+In summary, code that attempted to manipulate the behavior of the cycle GC
+may not work exactly as intended, but it is very unlikely to be harmful.
+All other code will work just fine.
+
+
getopt
------
@@ -2233,6 +2287,7 @@ asyncio
(Contributed by Yury Selivanov, Pablo Galindo Salgado, and Łukasz Langa
in :gh:`91048`.)
+
base64
------
@@ -2241,6 +2296,15 @@ base64
(Contributed by Bénédikt Tran, Chris Markiewicz, and Adam Turner in
:gh:`118761`.)
+gc
+--
+
+* The new :ref:`incremental garbage collector <whatsnew314-incremental-gc>`
+ means that maximum pause times are reduced
+ by an order of magnitude or more for larger heaps.
+ (Contributed by Mark Shannon in :gh:`108362`.)
+
+
io
---
* :mod:`io` which provides the built-in :func:`open` makes less system calls
@@ -2707,6 +2771,13 @@ Changes in the Python API
Wrap it in :func:`staticmethod` if you want to preserve the old behavior.
(Contributed by Serhiy Storchaka and Dominykas Grigonis in :gh:`121027`.)
+* The :ref:`garbage collector is now incremental <whatsnew314-incremental-gc>`,
+ which means that the behavior of :func:`gc.collect` changes slightly:
+
+ * ``gc.collect(1)``: Performs an increment of garbage collection,
+ rather than collecting generation 1.
+ * Other calls to :func:`!gc.collect` are unchanged.
+
* The :func:`locale.nl_langinfo` function now sets temporarily the ``LC_CTYPE``
locale in some cases.
This temporary change affects other threads.
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