Jul 1, 2025 · May 20, 2025 · May 22, 2025 · May 22, 2025 · May 27, 2025 · May 27, 2025
diff --git a/Doc/c-api/init.rst b/Doc/c-api/init.rst

   .. versionadded:: 3.13

 .. c:function:: int PyMutex_IsLocked(PyMutex *m)

   Returns non-zero if the mutex *m* is currently locked, zero otherwise.

   .. note::

      This function is intended for use in assertions and debugging only and
      should not be used to make concurrency control decisions, as the lock
      state may change immediately after the check.

   .. versionadded:: next

 .. _python-critical-section-api:

 Python Critical Section API
diff --git a/Doc/whatsnew/3.15.rst b/Doc/whatsnew/3.15.rst

  (Contributed by Serhiy Storchaka in :gh:`133595`.)

 * Private functions promoted to public C APIs:

  * ``PyMutex_IsLocked()`` : :c:func:`PyMutex_IsLocked`

  The |pythoncapi_compat_project| can be used to get most of these new
  functions on Python 3.14 and older.

 Deprecated C APIs
 -----------------

diff --git a/Include/cpython/lock.h b/Include/cpython/lock.h
 // exported function for unlocking the mutex
 PyAPI_FUNC(void) PyMutex_Unlock(PyMutex *m);

 // exported function for checking if the mutex is locked
 PyAPI_FUNC(int) PyMutex_IsLocked(PyMutex *m);

 // Locks the mutex.
 //
 // If the mutex is currently locked, the calling thread will be parked until
    }
 }
 #define PyMutex_Unlock _PyMutex_Unlock

 // Checks if the mutex is currently locked.
 static inline int
 _PyMutex_IsLocked(PyMutex *m)
 {
    return (_Py_atomic_load_uint8(&m->_bits) & _Py_LOCKED) != 0;
 }
 #define PyMutex_IsLocked _PyMutex_IsLocked
diff --git a/Include/internal/pycore_lock.h b/Include/internal/pycore_lock.h
    return _Py_atomic_compare_exchange_uint8(lock_bits, &expected, _Py_LOCKED);
 }

 // Checks if the mutex is currently locked.
 static inline int
 PyMutex_IsLocked(PyMutex *m)
 {
    return (_Py_atomic_load_uint8(&m->_bits) & _Py_LOCKED) != 0;
 }

 // Re-initializes the mutex after a fork to the unlocked state.
 static inline void
 _PyMutex_at_fork_reinit(PyMutex *m)
diff --git a/Misc/NEWS.d/next/C_API/2025-05-20-17-13-51.gh-issue-134009.CpCmry.rst b/Misc/NEWS.d/next/C_API/2025-05-20-17-13-51.gh-issue-134009.CpCmry.rst
 Expose:c:func:`PyMutex_IsLocked` as part of the public C API.
diff --git a/Python/lock.c b/Python/lock.c
        Py_FatalError("unlocking mutex that is not locked");
    }
 }


 #undef PyMutex_IsLocked
 int
 PyMutex_IsLocked(PyMutex *m)
 {
    return _PyMutex_IsLocked(m);
 }
Original file line number	Diff line number	Diff line change
Expand Up		@@ -2277,6 +2277,18 @@ The C-API provides a basic mutual exclusion lock.

		.. versionadded:: 3.13

		.. c:function:: int PyMutex_IsLocked(PyMutex *m)

		Returns non-zero if the mutex m is currently locked, zero otherwise.

		.. note::
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		This function is intended for use in assertions and debugging only and
		should not be used to make concurrency control decisions, as the lock
		state may change immediately after the check.

		.. versionadded:: next

		.. _python-critical-section-api:

		Python Critical Section API
Expand Down
Original file line number	Diff line number	Diff line change
Expand Up		@@ -324,6 +324,13 @@ Porting to Python 3.15

		(Contributed by Serhiy Storchaka in :gh:`133595`.)

		* Private functions promoted to public C APIs:

		* ``PyMutex_IsLocked()`` : :c:func:`PyMutex_IsLocked`

		The \|pythoncapi_compat_project\| can be used to get most of these new
		functions on Python 3.14 and older.

		Deprecated C APIs
		-----------------

Expand Down
Original file line number	Diff line number	Diff line change
Expand Up		@@ -36,6 +36,9 @@ PyAPI_FUNC(void) PyMutex_Lock(PyMutex *m);
		// exported function for unlocking the mutex
		PyAPI_FUNC(void) PyMutex_Unlock(PyMutex *m);

		// exported function for checking if the mutex is locked
		PyAPI_FUNC(int) PyMutex_IsLocked(PyMutex *m);

		// Locks the mutex.
		//
		// If the mutex is currently locked, the calling thread will be parked until
Expand All		@@ -61,3 +64,11 @@ _PyMutex_Unlock(PyMutex *m)
		}
		}
		#define PyMutex_Unlock _PyMutex_Unlock

		// Checks if the mutex is currently locked.
		static inline int
		_PyMutex_IsLocked(PyMutex *m)
		{
		return (_Py_atomic_load_uint8(&m->_bits) & _Py_LOCKED) != 0;
		}
		#define PyMutex_IsLocked _PyMutex_IsLocked
Original file line number	Diff line number	Diff line change
Expand Up		@@ -25,13 +25,6 @@ PyMutex_LockFast(PyMutex *m)
		return _Py_atomic_compare_exchange_uint8(lock_bits, &expected, _Py_LOCKED);
		}

		// Checks if the mutex is currently locked.
		static inline int
		PyMutex_IsLocked(PyMutex *m)
		{
		return (_Py_atomic_load_uint8(&m->_bits) & _Py_LOCKED) != 0;
		}

		// Re-initializes the mutex after a fork to the unlocked state.
		static inline void
		_PyMutex_at_fork_reinit(PyMutex *m)
Expand Down
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1 @@
		Expose:c:func:`PyMutex_IsLocked` as part of the public C API.
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Original file line number	Diff line number	Diff line change
Expand Up		@@ -622,3 +622,11 @@ PyMutex_Unlock(PyMutex *m)
		Py_FatalError("unlocking mutex that is not locked");
		}
		}


		#undef PyMutex_IsLocked
		int
		PyMutex_IsLocked(PyMutex *m)
		{
		return _PyMutex_IsLocked(m);
		}