title: tensorflow monitoredsession usage
body: <p>I have the following code to perform simple arithmetic calculations. I am trying to implement fault tolerance in it by using a Monitored Training session.</p>
  
  <pre><code>import tensorflow as tf
  
  global_step_tensor = tf.Variable(10, trainable=False, name='global_step')
  
  cluster = tf.train.ClusterSpec({"local": ["localhost:2222", "localhost:2223","localhost:2224", "localhost:2225"]})
  x = tf.constant(2)
  
  with tf.device("/job:local/task:0"):
      y1 = x + 300
  
  with tf.device("/job:local/task:1"):
      y2 = x**2
  
  with tf.device("/job:local/task:2"):
      y3 = 5*x
  
  with tf.device("/job:local/task:3"):
      y0 = x - 66
      y = y0 + y1 + y2 + y3
  
  ChiefSessionCreator = tf.train.ChiefSessionCreator(scaffold=None, master='localhost:2222', config='grpc://localhost:2222', checkpoint_dir='/home/tensorflow/codes/checkpoints')
  saver_hook = tf.train.CheckpointSaverHook(checkpoint_dir='/home/tensorflow/codes/checkpoints', save_secs=10, save_steps=None, saver=y, checkpoint_basename='model.ckpt', scaffold=None)
  summary_hook = tf.train.SummarySaverHook(save_steps=None, save_secs=10, output_dir='/home/tensorflow/codes/savepoints', summary_writer=None, scaffold=None, summary_op=y)
  
  with tf.train.MonitoredTrainingSession(master='localhost:2222', is_chief=True, checkpoint_dir='/home/tensorflow/codes/checkpoints', 
      scaffold=None, hooks=[saver_hook, summary_hook], chief_only_hooks=None, save_checkpoint_secs=10, save_summaries_steps=None, config='grpc://localhost:2222') as sess:
  
      while not sess.should_stop():
          sess.run(model)
  
      while not sess.should_stop():
          print(sess.run(y0))
          print('\n')
  
      while not sess.should_stop():
          print(sess.run(y1))
          print('\n')
  
      while not sess.should_stop():
          print(sess.run(y2))
          print('\n')
  
      while not sess.should_stop():
          print(sess.run(y3))
          print('\n')
  
      while not sess.should_stop():
          result = sess.run(y)
          print(result)
  </code></pre>
  
  <p>But it is throwing the following error:-</p>
  
  <pre><code> Traceback (most recent call last):
    File "add_1.py", line 36, in &lt;module&gt;
      scaffold=None, hooks=[saver_hook, summary_hook], chief_only_hooks=None, save_checkpoint_secs=10, save_summaries_steps=None, config='grpc://localhost:2222') as sess:
    File "/usr/local/lib/python2.7/dist-packages/tensorflow/python/training/monitored_session.py", line 289, in MonitoredTrainingSession
      return MonitoredSession(session_creator=session_creator, hooks=hooks)
    File "/usr/local/lib/python2.7/dist-packages/tensorflow/python/training/monitored_session.py", line 447, in __init__
      self._sess = _RecoverableSession(self._coordinated_creator)
    File "/usr/local/lib/python2.7/dist-packages/tensorflow/python/training/monitored_session.py", line 618, in __init__
      _WrappedSession.__init__(self, self._sess_creator.create_session())
    File "/usr/local/lib/python2.7/dist-packages/tensorflow/python/training/monitored_session.py", line 505, in create_session
      self.tf_sess = self._session_creator.create_session()
    File "/usr/local/lib/python2.7/dist-packages/tensorflow/python/training/monitored_session.py", line 341, in create_session
      init_fn=self._scaffold.init_fn)
    File "/usr/local/lib/python2.7/dist-packages/tensorflow/python/training/session_manager.py", line 227, in prepare_session
      config=config)
    File "/usr/local/lib/python2.7/dist-packages/tensorflow/python/training/session_manager.py", line 153, in _restore_checkpoint
      sess = session.Session(self._target, graph=self._graph, config=config)
    File "/usr/local/lib/python2.7/dist-packages/tensorflow/python/client/session.py", line 1186, in __init__
      super(Session, self).__init__(target, graph, config=config)
    File "/usr/local/lib/python2.7/dist-packages/tensorflow/python/client/session.py", line 540, in __init__
      % type(config))
  TypeError: config must be a tf.ConfigProto, but got &lt;type 'str'&gt;
  Exception AttributeError: "'Session' object has no attribute '_session'" in &lt;bound method Session.__del__ of &lt;tensorflow.python.client.session.Session object at 0x7fb1bac14ed0&gt;&gt; ignored
  </code></pre>
  
  <p>which in my opinion is due to incorrect argument given to config. Am I using the parameters right? Please advice.</p>