import tensorflow as tf

        self.sync_queue_counter % len(self.sync_queue_devices)]):
      sync_queues = [
          tf.FIFOQueue(num_workers, [tf.bool], shapes=[[]],
                       shared_name='%s%s' % (name_prefix, i))
          for i in range(num_workers)]
      queue_ops = []
      # For each other worker, add an entry in a queue, signaling that it can
      # finish this step.
      token = tf.constant(False)
      with tf.control_dependencies(enqueue_after_list):
        for i, q in enumerate(sync_queues):
          if i == self.task_index:
            queue_ops.append(tf.no_op())
          else:
            queue_ops.append(q.enqueue(token))

