Estou executando a rede cifar10 no meu PC e após concluir o treinamento e executar o script eval, o seguinte erro aparece:

2016-06-01 14:37:14.238317: precision @ 1 = 0.000
Traceback (most recent call last):

  File "<ipython-input-1-adf2ca85bb77>", line 1, in <module>
    runfile('/home/kang/Documents/work_code_PC1/py_tensorflow_learning/cifar10CNN_test/cifar10_eval_test.py', wdir='/home/kang/Documents/work_code_PC1/py_tensorflow_learning/cifar10CNN_test')

  File "/usr/lib/python3/dist-packages/spyderlib/widgets/externalshell/sitecustomize.py", line 685, in runfile
    execfile(filename, namespace)

  File "/usr/lib/python3/dist-packages/spyderlib/widgets/externalshell/sitecustomize.py", line 85, in execfile
    exec(compile(open(filename, 'rb').read(), filename, 'exec'), namespace)

  File "/home/kang/Documents/work_code_PC1/py_tensorflow_learning/cifar10CNN_test/cifar10_eval_test.py", line 107, in <module>
    tf.app.run()

  File "/usr/local/lib/python3.4/dist-packages/tensorflow/python/platform/default/_app.py", line 30, in run
    sys.exit(main(sys.argv))

  File "/home/kang/Documents/work_code_PC1/py_tensorflow_learning/cifar10CNN_test/cifar10_eval_test.py", line 104, in main
    evaluate()

  File "/home/kang/Documents/work_code_PC1/py_tensorflow_learning/cifar10CNN_test/cifar10_eval_test.py", line 94, in evaluate
    eval_once(saver, summary_writer, top_k_op, summary_op)

  File "/home/kang/Documents/work_code_PC1/py_tensorflow_learning/cifar10CNN_test/cifar10_eval_test.py", line 72, in eval_once
    coord.join(threads, stop_grace_period_secs = 10)

  File "/usr/local/lib/python3.4/dist-packages/tensorflow/python/training/coordinator.py", line 264, in join
    six.reraise(*self._exc_info_to_raise)

  File "/usr/lib/python3/dist-packages/six.py", line 659, in reraise
    raise value

  File "/usr/local/lib/python3.4/dist-packages/tensorflow/python/training/queue_runner.py", line 185, in _run
    sess.run(enqueue_op)

  File "/usr/local/lib/python3.4/dist-packages/tensorflow/python/client/session.py", line 315, in run
    return self._run(None, fetches, feed_dict)

  File "/usr/local/lib/python3.4/dist-packages/tensorflow/python/client/session.py", line 473, in _run
    raise RuntimeError('Attempted to use a closed Session.')

RuntimeError: Attempted to use a closed Session.

o que significa a sessão fechada? O train.py e o eval.py devem ser executados ao mesmo tempo? Eu sou novo no tensorflow e me digito de acordo com os códigos de demonstraçãohttps://www.tensorflow.org/versions/r0.8/tutorials/deep_cnn/index.html