gh-154757: Remove deprecated PyEval_InitThreads() function

Author: vstinner

Doc/c-api/interp-lifecycle.rst

@@ -74,8 +74,7 @@ The following functions can be safely called before Python is initialized:
 
    Despite their apparent similarity to some of the functions listed above,
    the following functions **should not be called** before the interpreter has
-   been initialized: :c:func:`Py_EncodeLocale`, :c:func:`PyEval_InitThreads`, and
-   :c:func:`Py_RunMain`.
+   been initialized: :c:func:`Py_EncodeLocale`, and :c:func:`Py_RunMain`.
 
 
 .. _global-conf-vars:
@@ -355,7 +354,6 @@ Initializing and finalizing the interpreter
 .. c:function:: void Py_Initialize()
 
    .. index::
-      single: PyEval_InitThreads()
       single: modules (in module sys)
       single: path (in module sys)
       pair: module; builtins

Doc/c-api/threads.rst

@@ -577,33 +577,6 @@ C extensions.
       This thread's interpreter state.
 
 
-.. c:function:: void PyEval_InitThreads()
-
-   .. index::
-      single: PyEval_AcquireThread()
-      single: PyEval_ReleaseThread()
-      single: PyEval_SaveThread()
-      single: PyEval_RestoreThread()
-
-   Deprecated function which does nothing.
-
-   In Python 3.6 and older, this function created the GIL if it didn't exist.
-
-   .. versionchanged:: 3.9
-      The function now does nothing.
-
-   .. versionchanged:: 3.7
-      This function is now called by :c:func:`Py_Initialize()`, so you don't
-      have to call it yourself anymore.
-
-   .. versionchanged:: 3.2
-      This function cannot be called before :c:func:`Py_Initialize()` anymore.
-
-   .. deprecated:: 3.9
-
-   .. index:: pair: module; _thread
-
-
 .. c:function:: PyThreadState* PyEval_SaveThread()
 
    Detach the :term:`attached thread state` and return it.

Doc/data/stable_abi.dat

@@ -3,6 +3,7 @@
 # Remove from here in 3.16
 c-api/allocation.html: deprecated-aliases
 c-api/file.html: deprecated-api
+c-api/threads.html: c.PyEval_InitThreads
 
 # Removed sections
 library/asyncio-task.html: terminating-a-task-group

Doc/tools/removed-ids.txt

@@ -1141,6 +1141,10 @@ Deprecated C APIs
 Removed C APIs
 --------------
 
+* Remove :c:func:`!PyEval_InitThreads` function which did nothing since Python
+  3.7 and was deprecated since Python 3.9.
+  (Contributed by Victor Stinner in :gh:`154757`.)
+
 * The :c:var:`!PyUnstable_ExecutableKinds` array, as well as the macros
   :c:macro:`!PyUnstable_EXECUTABLE_KIND_SKIP`,
   :c:macro:`!PyUnstable_EXECUTABLE_KIND_PY_FUNCTION`,

Doc/whatsnew/3.16.rst

@@ -111,8 +111,6 @@ PyAPI_FUNC(PyObject *) PyEval_EvalFrameEx(PyFrameObject *f, int exc);
 PyAPI_FUNC(PyThreadState *) PyEval_SaveThread(void);
 PyAPI_FUNC(void) PyEval_RestoreThread(PyThreadState *);
 
-Py_DEPRECATED(3.9) PyAPI_FUNC(void) PyEval_InitThreads(void);
-
 PyAPI_FUNC(void) PyEval_AcquireThread(PyThreadState *tstate);
 PyAPI_FUNC(void) PyEval_ReleaseThread(PyThreadState *tstate);
 

Include/ceval.h

@@ -0,0 +1,2 @@
+Remove :c:func:`!PyEval_InitThreads` function which did nothing since Python
+3.7 and was deprecated since Python 3.9. Patch by Victor Stinner.

Misc/NEWS.d/next/C_API/2026-09-23-23-52-55.gh-issue-154757.EUVFeZ.rst

@@ -715,6 +715,7 @@
     added = '3.2'
 [function.PyEval_InitThreads]
     added = '3.2'
+    abi_only = true
 [function.PyEval_ReleaseLock]
     added = '3.2'
     abi_only = true

Misc/stable_abi.toml

@@ -550,7 +550,8 @@ _PyEval_FiniGIL(PyInterpreterState *interp)
     interp->ceval.gil = NULL;
 }
 
-void
+// Function removed in Python 3.16 limited C API, but kept in the stable ABI
+PyAPI_FUNC(void)
 PyEval_InitThreads(void)
 {
     /* Do nothing: kept for backward compatibility */