Traceback (most recent call last):


 "/home/eric/Desktop/ray-private/python/ray/rllib/evaluation/policy_evaluator.py", line 659, in __del__

if isinstance(self.sampler, AsyncSampler):
AttributeError: 'PolicyEvaluator' object has no attribute 'sampler'

Traceback (most recent call last):


 "/home/guost/anaconda3/lib/python3.6/site-packages/torch/multiprocessing/reductions.py", line 26, in __del__
AttributeError: 'NoneType' object has no attribute '_free_weak_ref'
