Merge branch 'main' into typewatch

* main:
  pythongh-68686: Retire eptag ptag scripts (python#98064)
  pythongh-97922: Run the GC only on eval breaker (python#97920)
  GitHub Workflows security hardening (python#96492)
  Add `@ezio-melotti` as codeowner for `.github/`. (python#98079)
  pythongh-97913 Docs: Add walrus operator to the index (python#97921)
  [doc] Fix broken links to C extensions accelerating stdlib modules (python#96914)
  pythongh-97822: Fix http.server documentation reference to test() function (python#98027)
  pythongh-91052: Add PyDict_Unwatch for unwatching a dictionary (python#98055)
  pythonGH-98023: Change default child watcher to PidfdChildWatcher on supported systems (python#98024)
  pythonGH-94182: Run the PidfdChildWatcher on the running loop (python#94184)

Author: carljm

.github/CODEOWNERS

@@ -4,6 +4,9 @@
 # It uses the same pattern rule for gitignore file
 # https://git-scm.com/docs/gitignore#_pattern_format
 
+# GitHub
+.github/**                    @ezio-melotti
+
 # asyncio
 **/*asyncio*                  @1st1 @asvetlov @gvanrossum
 

.github/workflows/project-updater.yml

@@ -6,6 +6,9 @@ on:
       - opened
       - labeled
 
+permissions:
+  contents: read
+
 jobs:
   add-to-project:
     name: Add issues to projects

Doc/c-api/dict.rst

@@ -246,24 +246,41 @@ Dictionary Objects
    of error (e.g. no more watcher IDs available), return ``-1`` and set an
    exception.
 
+   .. versionadded:: 3.12
+
 .. c:function:: int PyDict_ClearWatcher(int watcher_id)
 
    Clear watcher identified by *watcher_id* previously returned from
    :c:func:`PyDict_AddWatcher`. Return ``0`` on success, ``-1`` on error (e.g.
    if the given *watcher_id* was never registered.)
 
+   .. versionadded:: 3.12
+
 .. c:function:: int PyDict_Watch(int watcher_id, PyObject *dict)
 
    Mark dictionary *dict* as watched. The callback granted *watcher_id* by
    :c:func:`PyDict_AddWatcher` will be called when *dict* is modified or
-   deallocated.
+   deallocated. Return ``0`` on success or ``-1`` on error.
+
+   .. versionadded:: 3.12
+
+.. c:function:: int PyDict_Unwatch(int watcher_id, PyObject *dict)
+
+   Mark dictionary *dict* as no longer watched. The callback granted
+   *watcher_id* by :c:func:`PyDict_AddWatcher` will no longer be called when
+   *dict* is modified or deallocated. The dict must previously have been
+   watched by this watcher. Return ``0`` on success or ``-1`` on error.
+
+   .. versionadded:: 3.12
 
 .. c:type:: PyDict_WatchEvent
 
    Enumeration of possible dictionary watcher events: ``PyDict_EVENT_ADDED``,
    ``PyDict_EVENT_MODIFIED``, ``PyDict_EVENT_DELETED``, ``PyDict_EVENT_CLONED``,
    ``PyDict_EVENT_CLEARED``, or ``PyDict_EVENT_DEALLOCATED``.
 
+   .. versionadded:: 3.12
+
 .. c:type:: int (*PyDict_WatchCallback)(PyDict_WatchEvent event, PyObject *dict, PyObject *key, PyObject *new_value)
 
    Type of a dict watcher callback function.
@@ -289,3 +306,5 @@ Dictionary Objects
    If the callback returns with an exception set, it must return ``-1``; this
    exception will be printed as an unraisable exception using
    :c:func:`PyErr_WriteUnraisable`. Otherwise it should return ``0``.
+
+   .. versionadded:: 3.12

Doc/library/http.server.rst

@@ -392,8 +392,8 @@ provides three different variants:
       contents of the file are output. If the file's MIME type starts with
       ``text/`` the file is opened in text mode; otherwise binary mode is used.
 
-      For example usage, see the implementation of the :func:`test` function
-      invocation in the :mod:`http.server` module.
+      For example usage, see the implementation of the ``test`` function
+      in :source:`Lib/http/server.py`.
 
       .. versionchanged:: 3.7
          Support of the ``'If-Modified-Since'`` header.

Doc/license.rst

@@ -302,7 +302,8 @@ for third-party software incorporated in the Python distribution.
 Mersenne Twister
 ----------------
 
-The :mod:`_random` module includes code based on a download from
+The :mod:`!_random` C extension underlying the :mod:`random` module
+includes code based on a download from
 http://www.math.sci.hiroshima-u.ac.jp/~m-mat/MT/MT2002/emt19937ar.html. The following are
 the verbatim comments from the original code::
 
@@ -819,7 +820,8 @@ sources unless the build is configured ``--with-system-expat``::
 libffi
 ------
 
-The :mod:`_ctypes` extension is built using an included copy of the libffi
+The :mod:`!_ctypes` C extension underlying the :mod:`ctypes` module
+is built using an included copy of the libffi
 sources unless the build is configured ``--with-system-libffi``::
 
    Copyright (c) 1996-2008  Red Hat, Inc and others.
@@ -920,7 +922,8 @@ on the cfuhash project::
 libmpdec
 --------
 
-The :mod:`_decimal` module is built using an included copy of the libmpdec
+The :mod:`!_decimal` C extension underlying the :mod:`decimal` module
+is built using an included copy of the libmpdec
 library unless the build is configured ``--with-system-libmpdec``::
 
    Copyright (c) 2008-2020 Stefan Krah. All rights reserved.

Doc/reference/expressions.rst

@@ -1741,6 +1741,12 @@ returns a boolean value regardless of the type of its argument
 (for example, ``not 'foo'`` produces ``False`` rather than ``''``.)
 
 
+.. index::
+   single: := (colon equals)
+   single: assignment expression
+   single: walrus operator
+   single: named expression
+
 Assignment expressions
 ======================
 

Doc/whatsnew/3.12.rst

@@ -93,6 +93,13 @@ Other Language Changes
   when parsing source code containing null bytes. (Contributed by Pablo Galindo
   in :gh:`96670`.)
 
+* The Garbage Collector now runs only on the eval breaker mechanism of the
+  Python bytecode evaluation loop instead on object allocations. The GC can
+  also run when :c:func:`PyErr_CheckSignals` is called so C extensions that
+  need to run for a long time without executing any Python code also have a
+  chance to execute the GC periodically. (Contributed by Pablo Galindo in
+  :gh:`97922`.)
+
 New Modules
 ===========
 
@@ -546,6 +553,11 @@ New Features
   which sets the vectorcall field of a given :c:type:`PyFunctionObject`.
   (Contributed by Andrew Frost in :gh:`92257`.)
 
+* The C API now permits registering callbacks via :c:func:`PyDict_AddWatcher`,
+  :c:func:`PyDict_AddWatch` and related APIs to be called whenever a dictionary
+  is modified. This is intended for use by optimizing interpreters, JIT
+  compilers, or debuggers.
+
 Porting to Python 3.12
 ----------------------
 

Include/cpython/dictobject.h

@@ -106,3 +106,4 @@ PyAPI_FUNC(int) PyDict_ClearWatcher(int watcher_id);
 
 // Mark given dictionary as "watched" (callback will be called if it is modified)
 PyAPI_FUNC(int) PyDict_Watch(int watcher_id, PyObject* dict);
+PyAPI_FUNC(int) PyDict_Unwatch(int watcher_id, PyObject* dict);

Include/internal/pycore_gc.h

@@ -202,6 +202,8 @@ extern void _PyList_ClearFreeList(PyInterpreterState *interp);
 extern void _PyDict_ClearFreeList(PyInterpreterState *interp);
 extern void _PyAsyncGen_ClearFreeLists(PyInterpreterState *interp);
 extern void _PyContext_ClearFreeList(PyInterpreterState *interp);
+extern void _Py_ScheduleGC(PyInterpreterState *interp);
+extern void _Py_RunGC(PyThreadState *tstate);
 
 #ifdef __cplusplus
 }

Include/internal/pycore_interp.h

@@ -49,6 +49,8 @@ struct _ceval_state {
     _Py_atomic_int eval_breaker;
     /* Request for dropping the GIL */
     _Py_atomic_int gil_drop_request;
+    /* The GC is ready to be executed */
+    _Py_atomic_int gc_scheduled;
     struct _pending_calls pending;
 };