Merge branch 'main' into thread_name_fix

Author: jadonduff

.github/CODEOWNERS

@@ -301,6 +301,15 @@ Dictionary Objects
       }
       Py_END_CRITICAL_SECTION();
 
+   .. note::
+
+      On the free-threaded build, this function can be used safely inside a
+      critical section. However, the references returned for *pkey* and *pvalue*
+      are :term:`borrowed <borrowed reference>` and are only valid while the
+      critical section is held. If you need to use these objects outside the
+      critical section or when the critical section can be suspended, create a
+      :term:`strong reference <strong reference>` (for example, using
+      :c:func:`Py_NewRef`).
 
 .. c:function:: int PyDict_Merge(PyObject *a, PyObject *b, int override)
 

Doc/c-api/dict.rst

@@ -2299,12 +2299,20 @@ per-object locks for :term:`free-threaded <free threading>` CPython.  They are
 intended to replace reliance on the :term:`global interpreter lock`, and are
 no-ops in versions of Python with the global interpreter lock.
 
+Critical sections are intended to be used for custom types implemented
+in C-API extensions. They should generally not be used with built-in types like
+:class:`list` and :class:`dict` because their public C-APIs
+already use critical sections internally, with the notable
+exception of :c:func:`PyDict_Next`, which requires critical section
+to be acquired externally.
+
 Critical sections avoid deadlocks by implicitly suspending active critical
-sections and releasing the locks during calls to :c:func:`PyEval_SaveThread`.
-When :c:func:`PyEval_RestoreThread` is called, the most recent critical section
-is resumed, and its locks reacquired.  This means the critical section API
-provides weaker guarantees than traditional locks -- they are useful because
-their behavior is similar to the :term:`GIL`.
+sections, hence, they do not provide exclusive access such as provided by
+traditional locks like :c:type:`PyMutex`.  When a critical section is started,
+the per-object lock for the object is acquired. If the code executed inside the
+critical section calls C-API functions then it can suspend the critical section thereby
+releasing the per-object lock, so other threads can acquire the per-object lock
+for the same object.
 
 Variants that accept :c:type:`PyMutex` pointers rather than Python objects are also
 available. Use these variants to start a critical section in a situation where

Doc/c-api/init.rst

@@ -1286,6 +1286,19 @@ and :c:data:`PyType_Type` effectively act as defaults.)
       :c:member:`~PyTypeObject.tp_weaklistoffset` field is set in a superclass.
 
 
+   .. c:macro:: Py_TPFLAGS_PREHEADER
+
+      These bits indicate that the VM will manage some fields by storing them
+      before the object. Currently, this macro is equivalent to
+      :c:expr:`Py_TPFLAGS_MANAGED_DICT | Py_TPFLAGS_MANAGED_WEAKREF`.
+
+      This macro value relies on the implementation of the VM, so its value is not
+      stable and may change in a future version. Prefer using individual
+      flags instead.
+
+      .. versionadded:: 3.12
+
+
    .. c:macro:: Py_TPFLAGS_ITEMS_AT_END
 
       Only usable with variable-size types, i.e. ones with non-zero

Doc/c-api/typeobj.rst

@@ -107,7 +107,7 @@ Glossary
       statements.
 
    asynchronous generator iterator
-      An object created by a :term:`asynchronous generator` function.
+      An object created by an :term:`asynchronous generator` function.
 
       This is an :term:`asynchronous iterator` which when called using the
       :meth:`~object.__anext__` method returns an awaitable object which will execute