Fetch the object after requesting reconstruction during ray.get (#301)

* Fetch the object after requesting reconstruction during ray.get

* revert

* Fix documentation and memory leak

* Fix hanging reconstruction bug

* Fix for python3

python/ray/worker.py

@@ -460,6 +460,7 @@ class Worker(object):
       object_ids (List[object_id.ObjectID]): A list of the object IDs whose
         values should be retrieved.
     """
+    # Do an initial fetch for remote objects.
     self.plasma_client.fetch([object_id.id() for object_id in object_ids])
 
     # Get the objects. We initially try to get the objects immediately.
@@ -477,6 +478,9 @@ class Worker(object):
     while len(unready_ids) > 0:
       for unready_id in unready_ids:
         self.photon_client.reconstruct_object(unready_id)
+      # Do another fetch for objects that aren't available locally yet, in case
+      # they were evicted since the last fetch.
+      self.plasma_client.fetch(list(unready_ids.keys()))
       results = numbuf.retrieve_list(list(unready_ids.keys()),
                                      self.plasma_client.conn,
                                      GET_TIMEOUT_MILLISECONDS)