[rllib] Fix stats collection and some docs bugs since the refactoring (#2361)

* fix

* fix pbt example

* fix

* fix

* single thread by default

* vec

* fix

* fix

python/ray/rllib/test/test_supported_spaces.py

@@ -5,6 +5,7 @@ import gym
 from gym.spaces import Box, Discrete, Tuple
 from gym.envs.registration import EnvSpec
 import numpy as np
+import sys
 
 import ray
 from ray.rllib.agents.agent import get_agent_class
@@ -117,4 +118,12 @@ class ModelSupportedSpaces(unittest.TestCase):
 
 
 if __name__ == "__main__":
+    if len(sys.argv) > 1 and sys.argv[1] == "--smoke":
+        ACTION_SPACES_TO_TEST = {
+            "discrete": Discrete(5),
+        }
+        OBSERVATION_SPACES_TO_TEST = {
+            "vector": Box(0.0, 1.0, (5,), dtype=np.float32),
+            "atari": Box(0.0, 1.0, (210, 160, 3), dtype=np.float32),
+        }
     unittest.main(verbosity=2)