gh-115942: Add locked to several multiprocessing locks

Doc/library/multiprocessing.rst

@@ -1421,6 +1421,13 @@ object -- see :ref:`multiprocessing-managers`.
       when invoked on an unlocked lock, a :exc:`ValueError` is raised.
 
 
+   .. method:: locked()
+
+      Returns a boolean whether this object is locked right now or not.
+
+      .. versionadded:: next
+
+
 .. class:: RLock()
 
    A recursive lock object: a close analog of :class:`threading.RLock`.  A
@@ -1481,6 +1488,13 @@ object -- see :ref:`multiprocessing-managers`.
       differs from the implemented behavior in :meth:`threading.RLock.release`.
 
 
+   .. method:: locked()
+
+      Returns a boolean whether this object is locked right now or not.
+
+      .. versionadded:: next
+
+
 .. class:: Semaphore([value])
 
    A semaphore object: a close analog of :class:`threading.Semaphore`.

Doc/library/threading.rst

@@ -709,6 +709,13 @@ call release as many times the lock has been acquired can lead to deadlock.
       There is no return value.
 
 
+   .. method:: locked()
+
+      Returns a boolean whether this object is locked right now or not.
+
+      .. versionadded:: next
+
+
 .. _condition-objects:
 
 Condition Objects

Lib/multiprocessing/managers.py

@@ -1059,20 +1059,22 @@ def close(self, *args):
 
 
 class AcquirerProxy(BaseProxy):
-    _exposed_ = ('acquire', 'release')
+    _exposed_ = ('acquire', 'release', 'locked')
     def acquire(self, blocking=True, timeout=None):
         args = (blocking,) if timeout is None else (blocking, timeout)
         return self._callmethod('acquire', args)
     def release(self):
         return self._callmethod('release')
+    def locked(self):
+        return self._callmethod('locked')
     def __enter__(self):
         return self._callmethod('acquire')
     def __exit__(self, exc_type, exc_val, exc_tb):
         return self._callmethod('release')
 
 
 class ConditionProxy(AcquirerProxy):
-    _exposed_ = ('acquire', 'release', 'wait', 'notify', 'notify_all')
+    _exposed_ = ('acquire', 'release', 'locked', 'wait', 'notify', 'notify_all')
     def wait(self, timeout=None):
         return self._callmethod('wait', (timeout,))
     def notify(self, n=1):

Lib/multiprocessing/synchronize.py

@@ -90,6 +90,9 @@ def _make_methods(self):
         self.acquire = self._semlock.acquire
         self.release = self._semlock.release
 
+    def locked(self):
+        return self._semlock._count() != 0
+
     def __enter__(self):
         return self._semlock.__enter__()
 

Lib/test/_test_multiprocessing.py

@@ -1486,8 +1486,10 @@ def test_repr_lock(self):
     def test_lock(self):
         lock = self.Lock()
         self.assertEqual(lock.acquire(), True)
+        self.assertTrue(lock.locked())
         self.assertEqual(lock.acquire(False), False)
         self.assertEqual(lock.release(), None)
+        self.assertFalse(lock.locked())
         self.assertRaises((ValueError, threading.ThreadError), lock.release)
 
     @staticmethod
@@ -1549,16 +1551,23 @@ def test_repr_rlock(self):
     def test_rlock(self):
         lock = self.RLock()
         self.assertEqual(lock.acquire(), True)
+        self.assertTrue(lock.locked())
         self.assertEqual(lock.acquire(), True)
         self.assertEqual(lock.acquire(), True)
         self.assertEqual(lock.release(), None)
+        self.assertTrue(lock.locked())
         self.assertEqual(lock.release(), None)
         self.assertEqual(lock.release(), None)
+        self.assertFalse(lock.locked())
         self.assertRaises((AssertionError, RuntimeError), lock.release)
 
     def test_lock_context(self):
-        with self.Lock():
-            pass
+        with self.Lock() as locked:
+            self.assertTrue(locked)
+
+    def test_rlock_context(self):
+        with self.RLock() as locked:
+            self.assertTrue(locked)
 
 
 class _TestSemaphore(BaseTestCase):

Misc/NEWS.d/next/Library/2025-04-01-11-16-22.gh-issue-115942.4W3hNx.rst

@@ -0,0 +1,5 @@
+Add :meth:`threading.RLock.locked`,
+:meth:`multiprocessing.Lock.locked`,
+:meth:`multiprocessing.RLock.locked`,
+and allow :meth:`multiprocessing.managers.SyncManager.Lock` and
+:meth:`multiprocessing.managers.SyncManager.RLock` to proxy ``locked()`` call.

Modules/_threadmodule.c

@@ -1086,6 +1086,19 @@ PyDoc_STRVAR(rlock_exit_doc,
 \n\
 Release the lock.");
 
+static PyObject *
+rlock_locked(PyObject *op, PyObject *Py_UNUSED(ignored))
+{
+    rlockobject *self = rlockobject_CAST(op);
+    int is_locked = _PyRecursiveMutex_IsLockedByCurrentThread(&self->lock);
+    return PyBool_FromLong(is_locked);
+}
+
+PyDoc_STRVAR(rlock_locked_doc,
+"locked()\n\
+\n\
+Returns whether this lock is locked right now or not.");
+
 static PyObject *
 rlock_acquire_restore(PyObject *op, PyObject *args)
 {
@@ -1204,6 +1217,8 @@ static PyMethodDef rlock_methods[] = {
      METH_VARARGS | METH_KEYWORDS, rlock_acquire_doc},
     {"release",      rlock_release,
      METH_NOARGS, rlock_release_doc},
+    {"locked",       rlock_locked,
+     METH_NOARGS, rlock_locked_doc},
     {"_is_owned",     rlock_is_owned,
      METH_NOARGS, rlock_is_owned_doc},
     {"_acquire_restore", rlock_acquire_restore,