message: Set gpu_options.allow_growth = True
  Reduces memory used for 199-lightning from 2552MiB to 523MiB.
diff: @@ -324,7 +324,9 @@ class StatisticsCollector(object):
  accuracy_summaries = tf.summary.merge(
  [policy_summary, value_summary, reg_summary, cost_summary],
  name="accuracy_summaries")
  - session = tf.Session(graph=graph)
  + config = tf.ConfigProto()
  + config.gpu_options.allow_growth = True
  + session = tf.Session(graph=tf.Graph(), config=config)
  def __init__(self):
  self.policy_costs = []
  