Speed up actor creation task submission by generating IDs with uuid. (#1744)

* Speed up actor creation task submission by generating IDs deterministically.

* Revert "Speed up actor creation task submission by generating IDs deterministically."

This reverts commit 175d9587302664916ce9db4071185485da8da041.

* Don't generate actor IDs deterministically yet.

* Factor out ID generation method.

python/ray/actor.py

@@ -12,18 +12,10 @@ import ray.cloudpickle as pickle
 import ray.local_scheduler
 import ray.signature as signature
 import ray.worker
-from ray.utils import (FunctionProperties, random_string, is_cython,
+from ray.utils import (FunctionProperties, _random_string, is_cython,
                        push_error_to_driver)
 
 
-def random_actor_id():
-    return ray.local_scheduler.ObjectID(random_string())
-
-
-def random_actor_class_id():
-    return random_string()
-
-
 def compute_actor_handle_id(actor_handle_id, num_forks):
     """Deterministically comopute an actor handle ID.
 
@@ -750,7 +742,7 @@ def actor_handle_from_class(Class, class_id, actor_creation_resources,
                 raise Exception("Actors cannot be created before ray.init() "
                                 "has been called.")
 
-            actor_id = random_actor_id()
+            actor_id = ray.local_scheduler.ObjectID(_random_string())
             # The ID for this instance of ActorHandle. These should be unique
             # across instances with the same _ray_actor_id.
             actor_handle_id = ray.local_scheduler.ObjectID(
@@ -930,7 +922,7 @@ def make_actor(cls, resources, checkpoint_interval, actor_method_cpus):
     Class.__module__ = cls.__module__
     Class.__name__ = cls.__name__
 
-    class_id = random_actor_class_id()
+    class_id = _random_string()
 
     return actor_handle_from_class(Class, class_id, resources,
                                    checkpoint_interval, actor_method_cpus)

python/ray/utils.py

@@ -4,9 +4,11 @@ from __future__ import print_function
 
 import binascii
 import collections
+import hashlib
 import numpy as np
 import os
 import sys
+import uuid
 
 import ray.local_scheduler
 
@@ -15,7 +17,11 @@ DRIVER_ID_LENGTH = 20
 
 
 def _random_string():
-    return np.random.bytes(20)
+    id_hash = hashlib.sha1()
+    id_hash.update(uuid.uuid4().bytes)
+    id_bytes = id_hash.digest()
+    assert len(id_bytes) == 20
+    return id_bytes
 
 
 def format_error_message(exception_message, task_exception=False):