Add actor.__ray_kill__() to terminate actors immediately (#6523)

python/ray/actor.py

@@ -642,7 +642,7 @@ class ActorHandle(object):
                                       self._actor_id.hex())
 
     def __del__(self):
-        """Kill the worker that is running this actor."""
+        """Terminate the worker that is running this actor."""
         # TODO(swang): Also clean up forked actor handles.
         # Kill the worker if this is the original actor handle, created
         # with Class.remote(). TODO(rkn): Even without passing handles around,
@@ -671,6 +671,20 @@ class ActorHandle(object):
             finally:
                 self.__ray_terminate__._actor_hard_ref = None
 
+    def __ray_kill__(self):
+        """Kill the actor that this actor handle refers to immediately.
+
+        This will cause any outstanding tasks submitted to the actor to fail
+        and the actor to exit in the same way as if it crashed. In general,
+        you should prefer to just delete the actor handle and let it clean up
+        gracefull.
+
+        Returns:
+            None.
+        """
+        worker = ray.worker.get_global_worker()
+        worker.core_worker.kill_actor(self._ray_actor_id)
+
     @property
     def _actor_id(self):
         return self._ray_actor_id