From 8e0962bb9c14253c01c97ea41bd715f952712e5b Mon Sep 17 00:00:00 2001
From: Alok Singh <8325708+alok@users.noreply.github.com>
Date: Sat, 19 May 2018 14:16:52 -0700
Subject: [PATCH] [rllib] rename async -> _async (#2097)

async and await are reserved words in Python 3.7, and will give a syntax error.
---
 python/ray/rllib/a3c/a3c_evaluator.py | 2 +-
 python/ray/rllib/utils/sampler.py     | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/python/ray/rllib/a3c/a3c_evaluator.py b/python/ray/rllib/a3c/a3c_evaluator.py
index 9b0522dfd..74d201016 100644
--- a/python/ray/rllib/a3c/a3c_evaluator.py
+++ b/python/ray/rllib/a3c/a3c_evaluator.py
@@ -45,7 +45,7 @@ class A3CEvaluator(PolicyEvaluator):
                         "rew_filter": self.rew_filter}
         self.sampler = AsyncSampler(env, self.policy, self.obs_filter,
                                     config["batch_size"])
-        if start_sampler and self.sampler.async:
+        if start_sampler and self.sampler._async:
             self.sampler.start()
         self.logdir = logdir
 
diff --git a/python/ray/rllib/utils/sampler.py b/python/ray/rllib/utils/sampler.py
index 8adc99605..242464dbf 100644
--- a/python/ray/rllib/utils/sampler.py
+++ b/python/ray/rllib/utils/sampler.py
@@ -90,7 +90,7 @@ class SyncSampler(object):
 
     This class provides data on invocation, rather than on a separate
     thread."""
-    async = False
+    _async = False
 
     def __init__(self, env, policy, obs_filter, num_local_steps, horizon=None):
         self.num_local_steps = num_local_steps
@@ -126,7 +126,7 @@ class AsyncSampler(threading.Thread):
 
     Note that batch_size is only a unit of measure here. Batches can
     accumulate and the gradient can be calculated on up to 5 batches."""
-    async = True
+    _async = True
 
     def __init__(self, env, policy, obs_filter, num_local_steps, horizon=None):
         assert getattr(