Clean up syntax for supported Python versions. (#1963)

* Use set/dict literal syntax

Ran code through [pyupgrade](https://github.com/asottile/pyupgrade). This is
supported in every Python version 2.7+.

* Drop unnecessary string format specification

No need to specify 0,1.. if paramters are passed in order.

* Revert "Drop unnecessary string format specification"

This reverts commit efa5ec85d30ff69f34e5ed93e31343fea7647bcb.

* Undo changes to cloudpickle

Drop use of set literal until cloudpickle uses it.

* Reformat code with YAPF

We need to set up a git pre-push hook to automatically run this stuff.

test/actor_test.py

@@ -774,7 +774,7 @@ class ActorsWithGPUs(unittest.TestCase):
         # Make sure that no two actors are assigned to the same GPU.
         locations_and_ids = ray.get(
             [actor.get_location_and_ids.remote() for actor in actors])
-        node_names = set([location for location, gpu_id in locations_and_ids])
+        node_names = {location for location, gpu_id in locations_and_ids}
         self.assertEqual(len(node_names), num_local_schedulers)
         location_actor_combinations = []
         for node_name in node_names:
@@ -815,7 +815,7 @@ class ActorsWithGPUs(unittest.TestCase):
         # Make sure that no two actors are assigned to the same GPU.
         locations_and_ids = ray.get(
             [actor.get_location_and_ids.remote() for actor in actors1])
-        node_names = set([location for location, gpu_id in locations_and_ids])
+        node_names = {location for location, gpu_id in locations_and_ids}
         self.assertEqual(len(node_names), num_local_schedulers)
 
         # Keep track of which GPU IDs are being used for each location.
@@ -847,9 +847,9 @@ class ActorsWithGPUs(unittest.TestCase):
         # Make sure that no two actors are assigned to the same GPU.
         locations_and_ids = ray.get(
             [actor.get_location_and_ids.remote() for actor in actors2])
-        self.assertEqual(
-            node_names,
-            set([location for location, gpu_id in locations_and_ids]))
+        self.assertEqual(node_names,
+                         {location
+                          for location, gpu_id in locations_and_ids})
         for location, gpu_ids in locations_and_ids:
             gpus_in_use[location].extend(gpu_ids)
         for node_name in node_names:
@@ -887,7 +887,7 @@ class ActorsWithGPUs(unittest.TestCase):
         # Make sure that no two actors are assigned to the same GPU.
         locations_and_ids = ray.get(
             [actor.get_location_and_ids.remote() for actor in actors])
-        node_names = set([location for location, gpu_id in locations_and_ids])
+        node_names = {location for location, gpu_id in locations_and_ids}
         self.assertEqual(len(node_names), 2)
         for node_name in node_names:
             node_gpu_ids = [
@@ -896,8 +896,8 @@ class ActorsWithGPUs(unittest.TestCase):
             ]
             self.assertIn(len(node_gpu_ids), [5, 10])
             self.assertEqual(
-                set(node_gpu_ids),
-                set([(i, ) for i in range(len(node_gpu_ids))]))
+                set(node_gpu_ids), {(i, )
+                                    for i in range(len(node_gpu_ids))})
 
         # Creating a new actor should fail because all of the GPUs are being
         # used.
@@ -1942,7 +1942,7 @@ class ActorPlacementAndResources(unittest.TestCase):
 
         results = ray.get([result1, result2, result3])
         self.assertEqual(results[0], results[2])
-        self.assertEqual(set(results), set([0, 1]))
+        self.assertEqual(set(results), {0, 1})
 
         # Make sure that when one actor goes out of scope a new actor is
         # created because some resources have been freed up.

test/runtest.py

@@ -255,7 +255,7 @@ class SerializationTest(unittest.TestCase):
 
         # Test sets.
         self.assertEqual(ray.get(f.remote(set())), set())
-        s = set([1, (1, 2, "hi")])
+        s = {1, (1, 2, "hi")}
         self.assertEqual(ray.get(f.remote(s)), s)
 
         # Test types.
@@ -1317,8 +1317,8 @@ class ResourcesTest(unittest.TestCase):
         self.assertEqual(list_of_ids, 10 * [[]])
 
         list_of_ids = ray.get([f1.remote() for _ in range(10)])
-        set_of_ids = set([tuple(gpu_ids) for gpu_ids in list_of_ids])
-        self.assertEqual(set_of_ids, set([(i, ) for i in range(10)]))
+        set_of_ids = {tuple(gpu_ids) for gpu_ids in list_of_ids}
+        self.assertEqual(set_of_ids, {(i, ) for i in range(10)})
 
         list_of_ids = ray.get([f2.remote(), f4.remote(), f4.remote()])
         all_ids = [gpu_id for gpu_ids in list_of_ids for gpu_id in gpu_ids]

test/stress_tests.py

@@ -210,8 +210,10 @@ class ReconstructionTests(unittest.TestCase):
         state._initialize_global_state(self.redis_ip_address, self.redis_port)
         if os.environ.get('RAY_USE_NEW_GCS', False):
             tasks = state.task_table()
-            local_scheduler_ids = set(
-                task["LocalSchedulerID"] for task in tasks.values())
+            local_scheduler_ids = {
+                task["LocalSchedulerID"]
+                for task in tasks.values()
+            }
 
         # Make sure that all nodes in the cluster were used by checking that
         # the set of local scheduler IDs that had a task scheduled or submitted