Update named actor API (#8559)

python/ray/worker.py

@@ -1657,7 +1657,22 @@ def wait(object_ids, num_returns=1, timeout=None):
         return ready_ids, remaining_ids
 
 
-def kill(actor):
+def get_actor(name):
+    """Get a handle to a detached actor.
+
+    Gets a handle to a detached actor with the given name. The actor must
+    have been created with Actor.options(name="name").remote().
+
+    Returns:
+        ActorHandle to the actor.
+
+    Raises:
+        ValueError if the named actor does not exist.
+    """
+    return ray.util.named_actors._get_actor(name)
+
+
+def kill(actor, no_restart=True):
     """Kill an actor forcefully.
 
     This will interrupt any running tasks on the actor, causing them to fail
@@ -1667,21 +1682,20 @@ def kill(actor):
     you can call ``actor.__ray_terminate__.remote()`` instead to queue a
     termination task.
 
-    In both cases, the worker is actually killed, but it will be restarted by
-    Ray.
-
-    If this actor is reconstructable, an attempt will be made to reconstruct
-    it.
+    If the actor is a detached actor, subsequent calls to get its handle via
+    ray.get_actor will fail.
 
     Args:
         actor (ActorHandle): Handle to the actor to kill.
+        no_restart (bool): Whether or not this actor should be restarted if
+            it's a restartable actor.
     """
     if not isinstance(actor, ray.actor.ActorHandle):
         raise ValueError("ray.kill() only supported for actors. "
                          "Got: {}.".format(type(actor)))
     worker = ray.worker.global_worker
     worker.check_connected()
-    worker.core_worker.kill_actor(actor._ray_actor_id, False)
+    worker.core_worker.kill_actor(actor._ray_actor_id, no_restart)
 
 
 def cancel(object_id, force=False):