How are the new tf.contrib.summary summaries in TensorFlow evaluated?

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answer moved from edit to self-answer as requested

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I just played around with this a little bit, and it seems that if one combines tf.control_dependencies with tf.record_summaries_every_n_global_steps it behaves as expected and the summary only gets recorded every nth step. But if they are run together within a session, such as session.run([train, summs]), the summaries are stored every once in a while, but not exactly every nth step. I tested this with n=2 and with the second approach the summary was often written at odd steps, while with the control dependency approach it was always on an even step.