Drupal 7 Batch API example

<?php

function skeleton_menu() {
  $items['admin/skeleton/batch'] = array(
    'title' => 'Skeleton Batch',
    'page callback' => 'skeleton_batch_init',
     'access arguments' => array('Administer content'),
    'type' => MENU_NORMAL_ITEM,
  );

  return $items;
}


function skeleton_batch_init() {
  $batch = array(
    'title' => t('Importing Content ...'),
    'operations' => array(),
    'init_message' => t('Commencing'),
    'progress_message' => t('Processed @current out of @total.'),
    'error_message' => t('An error occurred during processing'),
    'finished' => 'skeleton_batch_finished',
    'progressive' => FALSE
  );

  $nodes = array(
    'one',
    'two',
    'three',
    'four'
  );

  foreach ($nodes as $new_node) {
   $batch['operations'][] = array('skeleton_batch_worker', array($new_node));
  }

  batch_set($batch);

  batch_process('<front>');
}

function skeleton_batch_worker($new_node, &$context) {
/*
  $node = new stdClass();
  $node->type = 'article';
  node_object_prepare($node);

  $node->title = $new_node;
  $node->language = LANGUAGE_NONE;
  $node->body[$node->language][0]['value'] = $new_node;
  $node->body[$node->language][0]['summary'] = $new_node;

  $node->status = 1;

  node_save($node);
*/
  $context['results']['processed']++;
  $context['message'] = $new_node;
}

function skeleton_batch_finished($success, $results, $operations) {
  if ($success) {
    $message = format_plural($results['processed'], 'One node processed.', '@count nodes processed.');
  }
  else {
    $message = 'some errors';
  }

  drupal_set_message($message);
}