Add multiprocessing.Lock.locked()

Doc/library/multiprocessing.rst

@@ -1301,6 +1301,12 @@ object -- see :ref:`multiprocessing-managers`.
       Behavior is the same as in :meth:`threading.Lock.release` except that
       when invoked on an unlocked lock, a :exc:`ValueError` is raised.
 
+   .. method:: locked()
+
+      Return true if the lock is acquired.
+
+      .. versionadded:: 3.10
+
 
 .. class:: RLock()
 

Lib/multiprocessing/synchronize.py

@@ -161,6 +161,9 @@ class Lock(SemLock):
     def __init__(self, *, ctx):
         SemLock.__init__(self, SEMAPHORE, 1, 1, ctx=ctx)
 
+    def locked(self):
+        return self._semlock._is_zero()
+
     def __repr__(self):
         try:
             if self._semlock._is_mine():

Lib/test/_test_multiprocessing.py

@@ -1230,8 +1230,10 @@ class _TestLock(BaseTestCase):
     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)
 
     def test_rlock(self):

Misc/NEWS.d/next/Library/2020-06-05-15-47-43.bpo-40872.hW9afp.rst

@@ -0,0 +1,2 @@
+:class:`multiprocessing.Lock` now has a `locked()` method that returns
+whether the lock is currently held. Patch contributed by Rémi Lapeyre.