Introduce concept of resources required for placing a task. (#2837)

* Introduce concept of resources required for placement.
* Add placement resources to task spec
* Update java worker
* Update taskinfo.java

python/ray/actor.py

@@ -373,6 +373,15 @@ class ActorClass(object):
                 self._num_cpus, self._num_gpus, self._resources, num_cpus,
                 num_gpus, resources)
 
+            # If the actor methods require CPU resources, then set the required
+            # placement resources. If actor_placement_resources is empty, then
+            # the required placement resources will be the same as resources.
+            actor_placement_resources = {}
+            assert self._actor_method_cpus in [0, 1]
+            if self._actor_method_cpus == 1:
+                actor_placement_resources = resources.copy()
+                actor_placement_resources["CPU"] += 1
+
             creation_args = [self._class_id]
             function_id = compute_actor_creation_function_id(self._class_id)
             [actor_cursor] = worker.submit_task(
@@ -380,7 +389,8 @@ class ActorClass(object):
                 creation_args,
                 actor_creation_id=actor_id,
                 num_return_vals=1,
-                resources=resources)
+                resources=resources,
+                placement_resources=actor_placement_resources)
 
         # We initialize the actor counter at 1 to account for the actor
         # creation task.
@@ -566,6 +576,7 @@ class ActorHandle(object):
             # We add one for the dummy return ID.
             num_return_vals=num_return_vals + 1,
             resources={"CPU": self._ray_actor_method_cpus},
+            placement_resources={},
             driver_id=self._ray_actor_driver_id)
         # Update the actor counter and cursor to reflect the most recent
         # invocation.

python/ray/worker.py

@@ -550,6 +550,7 @@ class Worker(object):
                     execution_dependencies=None,
                     num_return_vals=None,
                     resources=None,
+                    placement_resources=None,
                     driver_id=None):
         """Submit a remote task to the scheduler.
 
@@ -575,6 +576,9 @@ class Worker(object):
             num_return_vals: The number of return values this function should
                 have.
             resources: The resource requirements for this task.
+            placement_resources: The resources required for placing the task.
+                If this is not provided or if it is an empty dictionary, then
+                the placement resources will be equal to resources.
             driver_id: The ID of the relevant driver. This is almost always the
                 driver ID of the driver that is currently running. However, in
                 the exceptional case that an actor task is being dispatched to
@@ -628,6 +632,9 @@ class Worker(object):
                     raise ValueError(
                         "Resource quantities must all be whole numbers.")
 
+            if placement_resources is None:
+                placement_resources = {}
+
             with self.state_lock:
                 # Increment the worker's task index to track how many tasks
                 # have been submitted by the current task so far.
@@ -640,7 +647,8 @@ class Worker(object):
                 num_return_vals, self.current_task_id, task_index,
                 actor_creation_id, actor_creation_dummy_object_id, actor_id,
                 actor_handle_id, actor_counter, is_actor_checkpoint_method,
-                execution_dependencies, resources, self.use_raylet)
+                execution_dependencies, resources, placement_resources,
+                self.use_raylet)
             self.local_scheduler_client.submit(task)
 
             return task.returns()
@@ -2138,7 +2146,7 @@ def connect(info,
             worker.current_task_id, worker.task_index,
             ray.ObjectID(NIL_ACTOR_ID), ray.ObjectID(NIL_ACTOR_ID),
             ray.ObjectID(NIL_ACTOR_ID), ray.ObjectID(NIL_ACTOR_ID),
-            nil_actor_counter, False, [], {"CPU": 0}, worker.use_raylet)
+            nil_actor_counter, False, [], {"CPU": 0}, {}, worker.use_raylet)
 
         # Add the driver task to the task table.
         if not worker.use_raylet: