gh-115942: Add locked to several multiprocessing locks (#115944)

Co-authored-by: mpage <mpage@cs.stanford.edu>
Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com>

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()
+
+      Return a boolean indicating whether this object is locked right now.
+
+      .. 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()
+
+      Return a boolean indicating whether this object is locked right now.
+
+      .. 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()
+
+      Return a boolean indicating whether this object is locked right now.
+
+      .. versionadded:: next
+
+
 .. _condition-objects:
 
 Condition Objects
@@ -801,6 +808,12 @@ item to the buffer only needs to wake up one consumer thread.
       Release the underlying lock. This method calls the corresponding method on
       the underlying lock; there is no return value.
 
+   .. method:: locked()
+
+      Return a boolean indicating whether this object is locked right now.
+
+      .. versionadded:: next
+
    .. method:: wait(timeout=None)
 
       Wait until notified or until a timeout occurs. If the calling thread has