if [[ "$TFCI_DOCKER_PULL_ENABLE" == 1 ]]; then
  # Simple retry logic for docker-pull errors. Sleeps for 15s if a pull fails.
  # Pulling an already-pulled container image will finish instantly, so
  # repeating the command costs nothing.
  docker pull "$TFCI_DOCKER_IMAGE" || sleep 15
  docker pull "$TFCI_DOCKER_IMAGE" || sleep 15
  docker pull "$TFCI_DOCKER_IMAGE"
fi 

      tf.data service
      (https://www.tensorflow.org/api_docs/python/tf/data/experimental/service)
      to write distributed dataset snapshots. The call is non-blocking and
      returns without waiting for the snapshot to finish. Setting `wait=True` to
      `tf.data.Dataset.load` allows the snapshots to be read while they are
      being written.

### Bug Fixes and Other Changes

  // until the previously pending operation (a StartExecute without a Join) has
  // finished, if any.
  //
  // `cancellation_manager` must live until after `Join` finishes and pending
  // `is_async` operations finish. In addition to allowing the caller to cancel
  // the operation, its `StartCancel` method will be called if op execution
  // fails on any device in order to cancel the others.