cpython/Include
Sam Gross 6ea4f842fb
[3.14] gh-144438: Fix false sharing between QSBR and tlbc_index (gh-144554) (#144923)
Align the QSBR thread state array to a 64-byte cache line boundary
and add padding at the end of _PyThreadStateImpl. Depending on heap
layout, the QSBR array could end up sharing a cache line with a
thread's tlbc_index, causing QSBR quiescent state updates to contend
with reads of tlbc_index in RESUME_CHECK. This is sensitive to
earlier allocations during interpreter init and can appear or
disappear with seemingly unrelated changes.

Either change alone is sufficient to fix the specific issue, but both
are worthwhile to avoid similar problems in the future.

(cherry picked from commit 6577d870b0)
2026-03-31 19:20:24 +00:00
..
cpython [3.14] gh-141732: Fix ExceptionGroup repr changing when original exception sequence is mutated (GH-141736) (GH-144445) 2026-03-23 23:31:32 +01:00
internal [3.14] gh-144438: Fix false sharing between QSBR and tlbc_index (gh-144554) (#144923) 2026-03-31 19:20:24 +00:00
abstract.h [3.14] gh-134989: Implement PyObject_DelAttr() as a macro in the limited C API (GH-135021) (#135133) 2025-06-04 13:33:20 +00:00
audit.h [3.14] gh-135755: Use private names (_Py*) for header file guards new in 3.14 (GH-135921) (GH-135976) 2025-07-01 12:37:02 +02:00
bltinmodule.h
boolobject.h [3.14] gh-134989: Fix Py_RETURN_NONE in the limited C API (GH-135165) (#135178) 2025-06-05 15:35:54 +02:00
bytearrayobject.h gh-87347: Add parenthesis around PyXXX_Check() arguments (#92815) 2022-06-16 13:49:43 +02:00
bytesobject.h gh-108765: Move standard includes to Python.h (#108769) 2023-09-01 21:03:20 +02:00
ceval.h [3.14] gh-135755: Move SPECIAL_ constants to a private header (GH-135922) (GH-135926) 2025-06-25 13:36:46 +02:00
codecs.h Remove private _PyCodec_Lookup() function (#106269) 2023-06-30 09:34:01 +00:00
compile.h gh-109596: Ensure repeated rules in the grammar are not allowed and fix incorrect soft keywords (#109606) 2023-09-22 19:03:23 +01:00
complexobject.h gh-87347: Add parenthesis around PyXXX_Check() arguments (#92815) 2022-06-16 13:49:43 +02:00
critical_section.h gh-119344: Make critical section API public (#119353) 2024-06-21 15:50:18 -04:00
datetime.h gh-87347: Add parenthesis around macro arguments (#93915) 2022-06-20 16:04:52 +02:00
descrobject.h gh-103509: PEP 697 -- Limited C API for Extending Opaque Types (GH-103511) 2023-05-04 09:56:53 +02:00
dictobject.h gh-106004: PyDict_GetItemRef() should only be in the limited API 3.13 (GH-107229) 2023-07-25 21:48:07 +03:00
dynamic_annotations.h gh-96959: Update HTTP links which are redirected to HTTPS (GH-96961) 2022-09-24 14:38:53 +03:00
enumobject.h
errcode.h gh-107450: Check for overflow in the tokenizer and fix overflow test (#110832) 2023-10-16 16:42:49 +02:00
exports.h gh-121040: Use __attribute__((fallthrough)) (#121044) 2024-06-27 09:58:44 +00:00
fileobject.h gh-106320: Remove _PyIsSelectable_fd() C API (#107142) 2023-07-23 19:07:12 +00:00
fileutils.h gh-108765: Move stat() fiddling from pyport.h to fileutils.h (#108854) 2023-09-03 21:32:13 +00:00
floatobject.h gh-120026: soft deprecate Py_HUGE_VAL macro (#120027) 2024-11-01 22:04:31 +00:00
frameobject.h bpo-45434: Remove useless space in includes (GH-28963) 2021-10-15 01:50:04 +02:00
genericaliasobject.h bpo-44654: Refactor and clean up the union type implementation (GH-27196) 2021-07-17 22:44:10 +03:00
import.h gh-105922: Add PyImport_AddModuleRef() function (#105923) 2023-06-20 08:48:14 +02:00
intrcheck.h gh-106320: Remove private _PyOS_IsMainThread() function (#108605) 2023-08-29 03:20:31 +00:00
iterobject.h gh-106320: Remove _PyAnextAwaitable_Type from the public C API (#108597) 2023-08-29 02:05:11 +00:00
listobject.h gh-114329: Fix PyList_GetItemRef() limited C API definition (#117520) 2024-04-03 21:02:42 +00:00
lock.h gh-117511: Make PyMutex public in the non-limited API (#117731) 2024-06-20 11:29:08 -04:00
longobject.h gh-132639: Adds PyLong_AsNativeBytes, PyLong_FromNativeBytes and PyLong_FromUnsignedNativeBytes to the limited API (GH-132640) 2025-04-21 15:59:03 +01:00
marshal.h gh-125063: marshal: Add version 5, improve documentation (GH-126829) 2024-11-15 13:48:57 +01:00
memoryobject.h gh-79315: Add Include/cpython/memoryobject.h header (#99723) 2022-11-23 15:44:42 +01:00
methodobject.h gh-132097: use a macro for semantically casting function pointers (#132406) 2025-04-18 12:24:34 +02:00
modsupport.h gh-112136: Restore removed _PyArg_Parser (#121262) 2024-07-03 18:36:57 +02:00
moduleobject.h gh-116322: Rename PyModule_ExperimentalSetGIL to PyUnstable_Module_SetGIL (GH-118645) 2024-05-06 18:59:36 +02:00
monitoring.h gh-111997: C-API for signalling monitoring events (#116413) 2024-05-04 08:23:50 +00:00
object.h [3.14] gh-145010: Fix Python.h compilation with -masm=intel (GH-145011) (#145776) 2026-03-10 18:07:17 +00:00
objimpl.h gh-102013: Move PyUnstable_GC_VisitObjects() to Include/cpython/objimpl.h (#115560) 2024-02-16 15:49:13 +01:00
opcode.h gh-100239: replace BINARY_SUBSCR & family by BINARY_OP with oparg NB_SUBSCR (#129700) 2025-02-07 22:39:54 +00:00
opcode_ids.h gh-100239: specialize BINARY_OP/SUBSCR for list-slice (#132626) 2025-05-01 10:28:52 +00:00
osdefs.h gh-108765: Reformat Include/osdefs.h (#108766) 2023-09-01 14:35:39 +00:00
osmodule.h Issue #29058: All stable API extensions added after Python 3.2 are now 2016-12-27 14:57:39 +02:00
patchlevel.h Post 3.14.3 2026-02-03 20:27:58 +02:00
py_curses.h bpo-44172: Keep reference to original window in curses subwindow objects (GH-26226) 2025-05-04 13:29:44 +03:00
pyatomic.h gh-108724: Add PyMutex and _PyParkingLot APIs (gh-109344) 2023-09-19 09:54:29 -06:00
pybuffer.h gh-102500: Implement PEP 688 (#102521) 2023-05-04 07:59:46 -07:00
pycapsule.h gh-108240: Add pycore_capsule.h internal header file (#108596) 2023-08-29 01:20:02 +00:00
pydtrace.d bpo-36842: Implement PEP 578 (GH-12613) 2019-05-23 08:45:22 -07:00
pydtrace.h Fix pydtrace.d path comment in Include/pydtrace.h (#28539) 2022-12-31 22:40:25 +05:30
pyerrors.h gh-119521: Rename IncompleteInputError to _IncompleteInputError and remove from public API/ABI (GH-119680) 2024-06-24 14:08:12 +02:00
pyexpat.h [3.14] gh-90949: add Expat API to prevent XML deadly allocations (CVE-2025-59375) (GH-139234) (#139359) 2025-11-02 09:33:36 +00:00
pyframe.h gh-93937, C API: Move PyFrame_GetBack() to Python.h (#93938) 2022-06-19 12:02:33 +02:00
pyhash.h gh-111545: Add Include/cpython/pyhash.h header file (#112063) 2023-11-15 01:19:20 +01:00
pylifecycle.h gh-117987: Restore several functions removed in Python 3.13 alpha 1 (GH-117993) 2024-04-18 15:20:38 +02:00
pymacconfig.h gh-110820: Make sure processor specific defines are correct for Universal 2 build on macOS (#112828) 2023-12-08 10:09:34 +01:00
pymacro.h [3.14] gh-141370: Fix undefined behavior when using Py_ABS() (GH-141548) (GH-142301) 2025-12-12 15:11:43 +00:00
pymath.h gh-120026: soft deprecate Py_HUGE_VAL macro (#120027) 2024-11-01 22:04:31 +00:00
pymem.h gh-85283: Add PyMem_RawMalloc() to the limited C API (#108570) 2023-10-17 02:41:51 +02:00
pyport.h [3.14] GH-139914: Handle stack growth direction on HPPA (GH-140028) (#141404) 2025-11-23 15:55:33 -08:00
pystate.h gh-108867: Add PyThreadState_GetUnchecked() function (#108870) 2023-10-03 16:53:51 +00:00
pystats.h GH-124284: Add stats for refcount operations on immortal objects (GH-124288) 2024-09-23 19:10:55 +01:00
pystrcmp.h
pystrtod.h gh-106320: Remove private float C API functions (#108430) 2023-08-24 19:09:49 +02:00
Python.h [3.14] gh-136823: Update documentation on excluded headers in Python.h (GH-136824) (#137437) 2025-10-07 23:23:33 +05:30
pythonrun.h [3.14] gh-130396: Move PYOS_LOG2_STACK_MARGIN to internal headers (GH-135928) (#136173) 2025-07-01 13:44:32 +00:00
pythread.h gh-87135: Hang non-main threads that attempt to acquire the GIL during finalization (GH-105805) 2024-10-02 09:17:49 -07:00
pytypedefs.h bpo-45459: Fix PyModuleDef_Slot type in the limited C API (GH-31668) 2022-03-03 23:06:55 +01:00
rangeobject.h gh-87347: Add parenthesis around PyXXX_Check() arguments (#92815) 2022-06-16 13:49:43 +02:00
README.rst gh-101101: Unstable C API tier (PEP 689) (GH-101102) 2023-02-28 09:31:01 +01:00
refcount.h [3.14] gh-140153: Fix Py_REFCNT() definition on limited C API 3.11-3.13 (GH-140158) (#140164) 2025-10-15 15:02:03 +00:00
setobject.h gh-87347: Add parenthesis around PyXXX_Check() arguments (#92815) 2022-06-16 13:49:43 +02:00
sliceobject.h gh-115754: Add Py_GetConstant() function (#116883) 2024-03-21 16:07:00 +00:00
structmember.h Fix typos in comments (#120188) 2024-06-07 10:19:41 +02:00
structseq.h gh-106168: PyTuple_SET_ITEM() now checks the index (#106164) 2023-06-28 03:45:57 +02:00
sysmodule.h gh-125604: Move _Py_AuditHookEntry, etc. Out of pycore_runtime.h (gh-125605) 2024-10-18 09:26:08 -06:00
traceback.h gh-87347: Add parenthesis around PyXXX_Check() arguments (#92815) 2022-06-16 13:49:43 +02:00
tupleobject.h gh-87347: Add parenthesis around PyXXX_Check() arguments (#92815) 2022-06-16 13:49:43 +02:00
typeslots.h Revert "gh-133395: add option for extension modules to specialize BINARY_OP/SUBSCR, apply to arrays (#133396)" (#133498) 2025-05-06 13:12:26 +03:00
unicodeobject.h gh-132798: Schedule removal of PyUnicode_AsDecoded/Encoded functions for 3.15 (#132799) 2025-04-25 15:07:41 +02:00
warnings.h bpo-35134: Split warnings.h and weakrefobject.h (GH-29042) 2021-10-19 01:31:57 +02:00
weakrefobject.h gh-105927: Limit PyWeakref_GetRef() to limited C API 3.13 (#117091) 2024-03-20 23:52:23 +01:00

The Python C API
================

The C API is divided into these sections:

1. ``Include/``: Limited API
2. ``Include/cpython/``: CPython implementation details
3. ``Include/cpython/``, names with the ``PyUnstable_`` prefix: API that can
   change between minor releases
4. ``Include/internal/``, and any name with ``_`` prefix: The internal API

Information on changing the C API is available `in the developer guide`_

.. _in the developer guide: https://devguide.python.org/c-api/