diff --git includes/batch.inc includes/batch.inc
index e886d7f..e66006c 100644
--- includes/batch.inc
+++ includes/batch.inc
@@ -6,7 +6,7 @@
  * @file
  * Batch processing API for processes to run in multiple HTTP requests.
  *
- * Please note that batches are usually invoked by form submissions, which is
+ * Note that batches are usually invoked by form submissions, which is
  * why the core interaction functions of the batch processing API live in
  * form.inc.
  *
@@ -62,8 +62,10 @@ function _batch_page() {
 
   // Add batch-specific CSS.
   foreach ($batch['sets'] as $batch_set) {
-    foreach ($batch_set['css'] as $css) {
-      drupal_add_css($css);
+    if (isset($batch_set['css'])) {
+      foreach ($batch_set['css'] as $css) {
+        drupal_add_css($css);
+      }
     }
   }
 
@@ -252,6 +254,12 @@ function _batch_process() {
     timer_start('batch_processing');
   }
 
+  if (empty($current_set['start'])) {
+    $current_set['start'] = microtime(TRUE);
+  }
+
+  $queue = _batch_queue($current_set);
+
   while (!$current_set['success']) {
     // If this is the first time we iterate this batch set in the current
     // request, we check if it requires an additional file for functions
@@ -261,42 +269,49 @@ function _batch_process() {
     }
 
     $task_message = '';
-    // We assume a single pass operation and set the completion level to 1 by
+    // Assume a single pass operation and set the completion level to 1 by
     // default.
     $finished = 1;
-    if ((list($function, $args) = reset($current_set['operations'])) && function_exists($function)) {
-      // Build the 'context' array, execute the function call, and retrieve the
-      // user message.
+
+    if ($item = $queue->claimItem()) {
+      list($function, $args) = $item->data;
+
+      // Build the 'context' array and execute the function call.
       $batch_context = array(
         'sandbox'  => &$current_set['sandbox'],
         'results'  => &$current_set['results'],
         'finished' => &$finished,
         'message'  => &$task_message,
       );
-      // Process the current operation.
       call_user_func_array($function, array_merge($args, array(&$batch_context)));
-    }
 
-    if ($finished == 1) {
-      // Make sure this step is not counted twice when computing $current.
-      $finished = 0;
-      // Remove the processed operation and clear the sandbox.
-      array_shift($current_set['operations']);
-      $current_set['sandbox'] = array();
+      if ($finished == 1) {
+        // Make sure this step is not counted twice when computing $current.
+        $finished = 0;
+        // Remove the processed operation and clear the sandbox.
+        $queue->deleteItem($item);
+        $current_set['count']--;
+        $current_set['sandbox'] = array();
+      }
     }
 
     // When all operations in the current batch set are completed, browse
-    // through the remaining sets until we find a set that contains operations.
-    // Note that _batch_next_set() executes stored form submit handlers in
-    // remaining batch sets, which can add new sets to the batch.
+    // through the remaining sets, marking them 'successfully processed'
+    // along the way, until we find a set that contains operations.
+    // _batch_next_set() executes form submit handlers stored in 'control'
+    // sets (see form_execute_handlers()), which can in turn add new sets to
+    // the batch.
     $set_changed = FALSE;
     $old_set = $current_set;
-    while (empty($current_set['operations']) && ($current_set['success'] = TRUE) && _batch_next_set()) {
+    while (empty($current_set['count']) && ($current_set['success'] = TRUE) && _batch_next_set()) {
       $current_set = &_batch_current_set();
+      $current_set['start'] = microtime(TRUE);
       $set_changed = TRUE;
     }
+
     // At this point, either $current_set contains operations that need to be
     // processed or all sets have been completed.
+    $queue = _batch_queue($current_set);
 
     // If we are in progressive mode, break processing after 1 second.
     if ($batch['progressive'] && timer_read('batch_processing') > 1000) {
@@ -312,33 +327,31 @@ function _batch_process() {
     // Reporting 100% progress will cause the whole batch to be considered
     // processed. If processing was paused right after moving to a new set,
     // we have to use the info from the new (unprocessed) set.
-    if ($set_changed && isset($current_set['operations'])) {
+    if ($set_changed && isset($current_set['queue'])) {
       // Processing will continue with a fresh batch set.
-      $remaining        = count($current_set['operations']);
+      $remaining        = $current_set['count'];
       $total            = $current_set['total'];
       $progress_message = $current_set['init_message'];
       $task_message     = '';
     }
     else {
       // Processing will continue with the current batch set.
-      $remaining        = count($old_set['operations']);
+      $remaining        = $old_set['count'];
       $total            = $old_set['total'];
       $progress_message = $old_set['progress_message'];
     }
 
-    $current = $total - $remaining + $finished;
+    $current    = $total - $remaining + $finished;
     $percentage = _batch_api_percentage($total, $current);
-
     $elapsed    = $current_set['elapsed'];
-    // Estimate remaining with percentage in floating format.
-    $estimate   = $elapsed * ($total - $current) / $current;
     $values     = array(
       '@remaining'  => $remaining,
       '@total'      => $total,
       '@current'    => floor($current),
       '@percentage' => $percentage,
       '@elapsed'    => format_interval($elapsed / 1000),
-      '@estimate'   => format_interval($estimate / 1000),
+      // If possible, estimate remaining processing time.
+      '@estimate'   => ($current > 0) ? format_interval(($elapsed * ($total - $current) / $current) / 1000) : '-',
     );
     $message = strtr($progress_message, $values);
     if (!empty($message)) {
@@ -410,7 +423,7 @@ function _batch_next_set() {
     if (isset($current_set['form_submit']) && ($function = $current_set['form_submit']) && function_exists($function)) {
       // We use our stored copies of $form and $form_state to account for
       // possible alterations by previous form submit handlers.
-      $function($batch['form'], $batch['form_state']);
+      $function($batch['form_state']['complete form'], $batch['form_state']);
     }
     return TRUE;
   }
@@ -426,15 +439,16 @@ function _batch_finished() {
   $batch = &batch_get();
 
   // Execute the 'finished' callbacks for each batch set, if defined.
-  foreach ($batch['sets'] as $key => $batch_set) {
+  foreach ($batch['sets'] as $batch_set) {
     if (isset($batch_set['finished'])) {
       // Check if the set requires an additional file for function definitions.
       if (isset($batch_set['file']) && is_file($batch_set['file'])) {
         include_once DRUPAL_ROOT . '/' . $batch_set['file'];
       }
       if (function_exists($batch_set['finished'])) {
-        // Format the elapsed time when batch complete.
-        $batch_set['finished']($batch_set['success'], $batch_set['results'], $batch_set['operations'], format_interval($batch_set['elapsed'] / 1000));
+        $queue = _batch_queue($batch_set);
+        $operations = $queue->getAllItems();
+        $batch_set['finished']($batch_set['success'], $batch_set['results'], $operations, format_interval($batch_set['elapsed'] / 1000));
       }
     }
   }
@@ -444,6 +458,11 @@ function _batch_finished() {
     db_delete('batch')
       ->condition('bid', $batch['id'])
       ->execute();
+    foreach ($batch['sets'] as $batch_set) {
+      if ($queue = _batch_queue($batch_set)) {
+        $queue->deleteQueue();
+      }
+    }
   }
   $_batch = $batch;
   $batch = NULL;
diff --git includes/form.inc includes/form.inc
index 58b0739..651d72e 100644
--- includes/form.inc
+++ includes/form.inc
@@ -634,12 +634,23 @@ function drupal_process_form($form_id, &$form, &$form_state) {
       // that is already being processed (if a batch operation performs a
       // drupal_form_submit).
       if ($batch =& batch_get() && !isset($batch['current_set'])) {
-        // The batch uses its own copies of $form and $form_state for
-        // late execution of submit handlers and post-batch redirection.
-        $batch['form'] = $form;
-        $batch['form_state'] = $form_state;
+        // Store $form_state information in the batch definition.
+        // We need the full $form_state when either:
+        // - Some submit handlers were saved to be called during batch
+        //   processing. See form_execute_handlers().
+        // - The form is multistep.
+        // In other cases, we only need the information expected by
+        // drupal_redirect_form().
+        if ($batch['has_form_submits'] || !empty($form_state['rebuild']) || !empty($form_state['storage'])) {
+          $batch['form_state'] = $form_state;
+        }
+        else {
+          $batch['form_state'] = array_intersect_key($form_state, array_flip(array('programmed', 'rebuild', 'storage', 'no_redirect', 'redirect')));
+        }
+
         $batch['progressive'] = !$form_state['programmed'];
         batch_process();
+
         // Execution continues only for programmatic forms.
         // For 'regular' forms, we get redirected to the batch processing
         // page. Form redirection will be handled in _batch_finished(),
@@ -1004,14 +1015,15 @@ function form_execute_handlers($type, &$form, &$form_state) {
 
   foreach ($handlers as $function) {
     if (function_exists($function))  {
-      // Check to see if a previous _submit handler has set a batch, but
-      // make sure we do not react to a batch that is already being processed
-      // (for instance if a batch operation performs a drupal_form_submit()).
-      if ($type == 'submit' && ($batch =& batch_get()) && !isset($batch['current_set'])) {
-        // Some previous _submit handler has set a batch. We store the call
-        // in a special 'control' batch set, for execution at the correct
-        // time during the batch processing workflow.
+      // Check if a previous _submit handler has set a batch, but make sure we
+      // do not react to a batch that is already being processed (for instance
+      // if a batch operation performs a drupal_form_submit()).
+      if ($type == 'submit' && ($batch =& batch_get()) && !isset($batch['id'])) {
+        // Some previous submit handler has set a batch. To ensure correct
+        // execution order, store the call in a special 'control' batch set.
+        // See _batch_next_set().
         $batch['sets'][] = array('form_submit' => $function);
+        $batch['has_form_submits'] = TRUE;
       }
       else {
         $function($form, $form_state);
@@ -3305,22 +3317,25 @@ function _form_set_class(&$element, $class = array()) {
 function batch_set($batch_definition) {
   if ($batch_definition) {
     $batch =& batch_get();
-    // Initialize the batch
+
+    // Initialize the batch if needed.
     if (empty($batch)) {
       $batch = array(
         'sets' => array(),
+        'has_form_submits' => FALSE,
       );
     }
 
+    // Base and default properties for the batch set.
+    // Use get_t() to allow batches at install time.
+    $t = get_t();
     $init = array(
       'sandbox' => array(),
       'results' => array(),
       'success' => FALSE,
-      'start' => microtime(TRUE),
+      'start' => 0,
       'elapsed' => 0,
     );
-    // Use get_t() to allow batches at install time.
-    $t = get_t();
     $defaults = array(
       'title' => $t('Processing'),
       'init_message' => $t('Initializing.'),
@@ -3330,20 +3345,29 @@ function batch_set($batch_definition) {
     );
     $batch_set = $init + $batch_definition + $defaults;
 
-    // Tweak init_message to avoid the bottom of the page flickering down after init phase.
+    // Tweak init_message to avoid the bottom of the page flickering down after
+    // init phase.
     $batch_set['init_message'] .= '<br/>&nbsp;';
+
+    // The non-concurrent workflow of batch execution allows us to save
+    // numberOfItems() queries by handling our own counter.
     $batch_set['total'] = count($batch_set['operations']);
+    $batch_set['count'] = $batch_set['total'];
 
-    // If the batch is being processed (meaning we are executing a stored submit handler),
-    // insert the new set after the current one.
-    if (isset($batch['current_set'])) {
-      // array_insert does not exist...
-      $slice1 = array_slice($batch['sets'], 0, $batch['current_set'] + 1);
-      $slice2 = array_slice($batch['sets'], $batch['current_set'] + 1);
-      $batch['sets'] = array_merge($slice1, array($batch_set), $slice2);
+    // Add the set to the batch.
+    if (empty($batch['id'])) {
+      // The batch is not running yet. Simply add the new set.
+      $batch['sets'][] = $batch_set;
     }
     else {
-      $batch['sets'][] = $batch_set;
+      // The set is being added while the batch is running. Insert the new set
+      // right after the current one to ensure execution order, and store its
+      // operations in a queue.
+      $index = $batch['current_set'] + 1;
+      $slice1 = array_slice($batch['sets'], 0, $index);
+      $slice2 = array_slice($batch['sets'], $index);
+      $batch['sets'] = array_merge($slice1, array($batch_set), $slice2);
+      _batch_populate_queue($batch, $index);
     }
   }
 }
@@ -3387,11 +3411,28 @@ function batch_process($redirect = NULL, $url = 'batch', $redirect_callback = 'd
     );
     $batch += $process_info;
 
-    // The batch is now completely built. Allow other modules to make changes to the
-    // batch so that it is easier to reuse batch processes in other enviroments.
+    // The batch is now completely built. Allow other modules to make changes
+    // to the batch so that it is easier to reuse batch processes in other
+    // enviroments.
     drupal_alter('batch', $batch);
 
+    // Assign an arbitrary id: don't rely on a serial column in the 'batch'
+    // table, since non-progressive batches skip database storage completely.
+    $batch['id'] = db_next_id();
+
+    // Move operations to a job queue. Non-progressive batches will use a
+    // memory-based queue.
+    foreach ($batch['sets'] as $key => $batch_set) {
+      _batch_populate_queue($batch, $key);
+    }
+
+    // Initiate processing.
     if ($batch['progressive']) {
+      // Now that we have a batch id, we can generate the redirection link in
+      // the generic error message.
+      $t = get_t();
+      $batch['error_message'] = $t('Please continue to <a href="@error_url">the error page</a>', array('@error_url' => url($url, array('query' => array('id' => $batch['id'], 'op' => 'finished')))));
+
       // Clear the way for the drupal_goto() redirection to the batch processing
       // page, by saving and unsetting the 'destination', if there is any.
       if (isset($_GET['destination'])) {
@@ -3399,24 +3440,11 @@ function batch_process($redirect = NULL, $url = 'batch', $redirect_callback = 'd
         unset($_GET['destination']);
       }
 
-      // Initiate db storage in order to get a batch id. We have to provide
-      // at least an empty string for the (not null) 'token' column.
-      $batch['id'] = db_insert('batch')
+      // Store the batch.
+      db_insert('batch')
         ->fields(array(
-          'token' => '',
+          'bid' => $batch['id'],
           'timestamp' => REQUEST_TIME,
-        ))
-        ->execute();
-
-      // Now that we have a batch id, we can generate the redirection link in
-      // the generic error message.
-      $t = get_t();
-      $batch['error_message'] = $t('Please continue to <a href="@error_url">the error page</a>', array('@error_url' => url($url, array('query' => array('id' => $batch['id'], 'op' => 'finished')))));
-
-      // Actually store the batch data and the token generated form the batch id.
-      db_update('batch')
-        ->condition('bid', $batch['id'])
-        ->fields(array(
           'token' => drupal_get_token($batch['id']),
           'batch' => serialize($batch),
         ))
@@ -3425,6 +3453,7 @@ function batch_process($redirect = NULL, $url = 'batch', $redirect_callback = 'd
       // Set the batch number in the session to guarantee that it will stay alive.
       $_SESSION['batches'][$batch['id']] = TRUE;
 
+      // Redirect for processing.
       $function = $batch['redirect_callback'];
       if (function_exists($function)) {
         $function($batch['url'], array('query' => array('op' => 'start', 'id' => $batch['id'])));
@@ -3454,5 +3483,69 @@ function &batch_get() {
 }
 
 /**
+ * Populates a job queue with the operations of a batch set.
+ *
+ * Depending on whether the batch is progressive or not, the BatchQueue or
+ * BatchStaticQueue handler classes will be used.
+ *
+ * @param $batch
+ *   The batch array.
+ * @param $set_id
+ *   The id of the set to process.
+ * @return
+ *   The name and class of the queue are added by reference to the batch set.
+ */
+function _batch_populate_queue(&$batch, $set_id) {
+  $batch_set = &$batch['sets'][$set_id];
+
+  if (isset($batch_set['operations'])) {
+    $batch_set += array(
+      'queue' => array(
+        'name' => 'drupal_batch:' . $batch['id'] . ':' . $set_id,
+        'class' => $batch['progressive'] ? 'BatchQueue' : 'BatchMemoryQueue',
+      ),
+    );
+
+    $queue = _batch_queue($batch_set);
+    $queue->createQueue();
+    foreach ($batch_set['operations'] as $operation) {
+      $queue->createItem($operation);
+    }
+
+    unset($batch_set['operations']);
+  }
+}
+
+/**
+ * Returns a queue object for a batch set.
+ *
+ * @param $batch_set
+ *   The batch set.
+ * @return
+ *   The queue object.
+ */
+function _batch_queue($batch_set) {
+  static $queues;
+
+  // The class autoloader is not available when running update.php, so make
+  // sure the files are manually included.
+  if (is_null($queues)) {
+    $queues = array();
+    require_once DRUPAL_ROOT . '/modules/system/system.queue.inc';
+    require_once DRUPAL_ROOT . '/includes/batch.queue.inc';
+  }
+
+  if (isset($batch_set['queue'])) {
+    $name = $batch_set['queue']['name'];
+    $class = $batch_set['queue']['class'];
+
+    if (!isset($queues[$class][$name])) {
+      $queues[$class][$name] = new $class($name);
+    }
+    return $queues[$class][$name];
+  }
+}
+
+/**
  * @} End of "defgroup batch".
  */
diff --git includes/update.inc includes/update.inc
index b39db06..f86a1f2 100644
--- includes/update.inc
+++ includes/update.inc
@@ -338,6 +338,51 @@ function update_fix_d7_requirements() {
     db_create_table('date_formats', $schema['date_formats']);
     db_create_table('date_format_locale', $schema['date_format_locale']);
 
+    // Add the queue table.
+    $schema['queue'] = array(
+      'description' => 'Stores items in queues.',
+      'fields' => array(
+        'item_id' => array(
+          'type' => 'serial',
+          'unsigned' => TRUE,
+          'not null' => TRUE,
+          'description' => 'Primary Key: Unique item ID.',
+        ),
+        'name' => array(
+          'type' => 'varchar',
+          'length' => 255,
+          'not null' => TRUE,
+          'default' => '',
+          'description' => 'The queue name.',
+        ),
+        'data' => array(
+          'type' => 'text',
+          'not null' => FALSE,
+          'size' => 'big',
+          'serialize' => TRUE,
+          'description' => 'The arbitrary data for the item.',
+        ),
+        'expire' => array(
+          'type' => 'int',
+          'not null' => TRUE,
+          'default' => 0,
+          'description' => 'Timestamp when the claim lease expires on the item.',
+        ),
+        'created' => array(
+          'type' => 'int',
+          'not null' => TRUE,
+          'default' => 0,
+          'description' => 'Timestamp when the item was created.',
+        ),
+      ),
+      'primary key' => array('item_id'),
+      'indexes' => array(
+        'name_created' => array('name', 'created'),
+        'expire' => array('expire'),
+      ),
+    );
+    db_create_table('queue', $schema['queue']);
+
     // Add column for locale context.
     if (db_table_exists('locales_source')) {
       db_add_field('locales_source', 'context', array('type' => 'varchar', 'length' => 255, 'not null' => TRUE, 'default' => '', 'description' => 'The context this string applies to.'));
diff --git modules/simpletest/tests/batch.test modules/simpletest/tests/batch.test
index d28c65d..ffd3fab 100644
--- modules/simpletest/tests/batch.test
+++ modules/simpletest/tests/batch.test
@@ -3,40 +3,286 @@
 
 /**
  * @file
- * Unit tests for the Drupal Batch API.
+ * Tests for the Batch API.
  */
 
 /**
- * Tests for the batch API progress page theme.
+ * Tests for the Batch API.
  */
-class BatchAPIThemeTestCase extends DrupalWebTestCase {
+class BatchProcessingTestCase extends DrupalWebTestCase {
   public static function getInfo() {
     return array(
-      'name' => 'Batch API progress page theme',
-      'description' => 'Tests that while a progressive batch is running, it correctly uses the theme of the page that started the batch.',
+      'name' => 'Batch processing',
+      'description' => 'Test batch processing in form and non-form workflow.',
       'group' => 'Batch API',
     );
   }
 
   function setUp() {
-    parent::setUp('system_test');
-    // Make sure that the page which starts the batch (an administrative page)
-    // is using a different theme than would normally be used by the batch API.
-    variable_set('theme_default', 'garland');
-    variable_set('admin_theme', 'seven');
+    parent::setUp('batch_test');
+  }
+
+  /**
+   * Test batches triggered outside of form submission.
+   */
+  function testBatchNoForm() {
+    // Displaying the page triggers batch 1.
+    $this->drupalGet('batch_test/no_form');
+    $this->assertBatchMessages($this->_resultMessages(1), t('Batch for step 2 performed successfully.'));
+    $this->assertEqual(batch_test_stack(), $this->_resultStack('batch_1'), t('Execution order was correct.'));
+    $this->assertText('Redirection successful.', t('Redirection after batch execution is correct.'));
+  }
+
+  /**
+   * Test batches defined in a form submit handler.
+   */
+  function testBatchForm() {
+    // Batch 0: no operation.
+    $edit = array('batch' => 'batch_0');
+    $this->drupalPost('batch_test/simple', $edit, 'Submit');
+    $this->assertBatchMessages($this->_resultMessages('batch_0'), t('Batch with no operation performed successfully.'));
+    $this->assertText('Redirection successful.', t('Redirection after batch execution is correct.'));
+
+    // Batch 1: several simple operations.
+    $edit = array('batch' => 'batch_1');
+    $this->drupalPost('batch_test/simple', $edit, 'Submit');
+    $this->assertBatchMessages($this->_resultMessages('batch_1'), t('Batch with simple operations performed successfully.'));
+    $this->assertEqual(batch_test_stack(), $this->_resultStack('batch_1'), t('Execution order was correct.'));
+    $this->assertText('Redirection successful.', t('Redirection after batch execution is correct.'));
+
+    // Batch 2: one multistep operation.
+    $edit = array('batch' => 'batch_2');
+    $this->drupalPost('batch_test/simple', $edit, 'Submit');
+    $this->assertBatchMessages($this->_resultMessages('batch_2'), t('Batch with multistep operation performed successfully.'));
+    $this->assertEqual(batch_test_stack(), $this->_resultStack('batch_2'), t('Execution order was correct.'));
+    $this->assertText('Redirection successful.', t('Redirection after batch execution is correct.'));
+
+    // Batch 3: simple + multistep combined.
+    $edit = array('batch' => 'batch_3');
+    $this->drupalPost('batch_test/simple', $edit, 'Submit');
+    $this->assertBatchMessages($this->_resultMessages('batch_3'), t('Batch with simple and multistep operations performed successfully.'));
+    $this->assertEqual(batch_test_stack(), $this->_resultStack('batch_3'), t('Execution order was correct.'));
+    $this->assertText('Redirection successful.', t('Redirection after batch execution is correct.'));
+
+    // Batch 4: nested batch.
+    $edit = array('batch' => 'batch_4');
+    $this->drupalPost('batch_test/simple', $edit, 'Submit');
+    $this->assertBatchMessages($this->_resultMessages('batch_4'), t('Nested batch performed successfully.'));
+    $this->assertEqual(batch_test_stack(), $this->_resultStack('batch_4'), t('Execution order was correct.'));
+    $this->assertText('Redirection successful.', t('Redirection after batch execution is correct.'));
+  }
+
+  /**
+   * Test batches defined in a multistep form.
+   */
+  function testBatchFormMultistep() {
+    $this->drupalGet('batch_test/multistep');
+    $this->assertText('step 1', t('Form is displayed in step 1.'));
+
+    // First step triggers batch 1.
+    $this->drupalPost(NULL, array(), 'Submit');
+    $this->assertBatchMessages($this->_resultMessages('batch_1'), t('Batch for step 1 performed successfully.'));
+    $this->assertEqual(batch_test_stack(), $this->_resultStack('batch_1'), t('Execution order was correct.'));
+    $this->assertText('step 2', t('Form is displayed in step 2.'));
+
+    // Second step triggers batch 2.
+    $this->drupalPost(NULL, array(), 'Submit');
+    $this->assertBatchMessages($this->_resultMessages('batch_2'), t('Batch for step 2 performed successfully.'));
+    $this->assertEqual(batch_test_stack(), $this->_resultStack('batch_2'), t('Execution order was correct.'));
+    $this->assertText('Redirection successful.', t('Redirection after batch execution is correct.'));
+  }
+
+  /**
+   * Test batches defined in different submit handlers on the same form.
+   */
+  function testBatchFormMultipleBatches() {
+    // Batches 1, 2 and 3 are triggered in sequence by different submit
+    // handlers. Each submit handler modify the submitted 'value'.
+    $value = rand(0, 255);
+    $edit = array('value' => $value);
+    $this->drupalPost('batch_test/chained', $edit, 'Submit');
+    // Check that result messages are present and in the correct order.
+    $this->assertBatchMessages($this->_resultMessages('chained'), t('Batches defined in separate submit handlers performed successfully.'));
+    // The stack contains execution order of batch callbacks and submit
+    // hanlders and logging of corresponding $form_state[{values'].
+    $this->assertEqual(batch_test_stack(), $this->_resultStack('chained', $value), t('Execution order was correct, and $form_state is correctly persisted.'));
+    $this->assertText('Redirection successful.', t('Redirection after batch execution is correct.'));
+  }
+
+  /**
+   * Test batches defined in a programmatically submitted form.
+   *
+   * Same as above, but the form is submitted through drupal_form_execute().
+   */
+  function testBatchFormProgrammatic() {
+    // Batches 1, 2 and 3 are triggered in sequence by different submit
+    // handlers. Each submit handler modify the submitted 'value'.
+    $value = rand(0, 255);
+    $this->drupalGet('batch_test/programmatic/' . $value);
+    // Check that result messages are present and in the correct order.
+    $this->assertBatchMessages($this->_resultMessages('chained'), t('Batches defined in separate submit handlers performed successfully.'));
+    // The stack contains execution order of batch callbacks and submit
+    // hanlders and logging of corresponding $form_state[{values'].
+    $this->assertEqual(batch_test_stack(), $this->_resultStack('chained', $value), t('Execution order was correct, and $form_state is correctly persisted.'));
+    $this->assertText('Got out of a programmatic batched form.', t('Page execution continues normally.'));
+  }
+
+  /**
+   * Test that drupal_form_submit() can run within a batch operation.
+   */
+  function testDrupalFormSubmitInBatch() {
+    // Displaying the page triggers a batch that programmatically submits a
+    // form.
+    $value = rand(0, 255);
+    $this->drupalGet('batch_test/nested_programmatic/' . $value);
+    $this->assertEqual(batch_test_stack(), array('mock form submitted with value = ' . $value), t('drupal_form_submit() ran successfully within a batch operation.'));
+  }
+
+  /**
+   * Will trigger a pass if the texts were found in order in the raw content.
+   *
+   * @param $texts
+   *   Array of raw strings to look for .
+   * @param $message
+   *   Message to display.
+   * @return
+   *   TRUE on pass, FALSE on fail.
+   */
+  function assertBatchMessages($texts, $message) {
+    $pattern = '|' . implode('.*', $texts) .'|s';
+    return $this->assertPattern($pattern, $message);
+  }
+
+  /**
+   * Helper function: return expected execution stacks for the test batches.
+   */
+  function _resultStack($id, $value = 0) {
+    $stack = array();
+    switch ($id) {
+      case 'batch_1':
+        for ($i = 1; $i <= 10; $i++) {
+          $stack[] = "op 1 id $i";
+        }
+        break;
+
+      case 'batch_2':
+        for ($i = 1; $i <= 10; $i++) {
+          $stack[] = "op 2 id $i";
+        }
+        break;
+
+      case 'batch_3':
+        for ($i = 1; $i <= 5; $i++) {
+          $stack[] = "op 1 id $i";
+        }
+        for ($i = 1; $i <= 5; $i++) {
+          $stack[] = "op 2 id $i";
+        }
+        for ($i = 6; $i <= 10; $i++) {
+          $stack[] = "op 1 id $i";
+        }
+        for ($i = 6; $i <= 10; $i++) {
+          $stack[] = "op 2 id $i";
+        }
+        break;
+
+      case 'batch_4':
+        for ($i = 1; $i <= 5; $i++) {
+          $stack[] = "op 1 id $i";
+        }
+        $stack[] = 'setting up batch 2';
+        for ($i = 6; $i <= 10; $i++) {
+          $stack[] = "op 1 id $i";
+        }
+        $stack = array_merge($stack, $this->_resultStack('batch_2'));
+        break;
+
+      case 'chained':
+        $stack[] = 'submit handler 1';
+        $stack[] = 'value = ' . $value;
+        $stack = array_merge($stack, $this->_resultStack('batch_1'));
+        $stack[] = 'submit handler 2';
+        $stack[] = 'value = ' . ($value + 1);
+        $stack = array_merge($stack, $this->_resultStack('batch_2'));
+        $stack[] = 'submit handler 3';
+        $stack[] = 'value = ' . ($value + 2);
+        $stack[] = 'submit handler 4';
+        $stack[] = 'value = ' . ($value + 3);
+        $stack = array_merge($stack, $this->_resultStack('batch_3'));
+        break;
+    }
+    return $stack;
+  }
+
+  /**
+   * Helper function: return expected result messages for the test batches.
+   */
+  function _resultMessages($id) {
+    $messages = array();
+
+    switch ($id) {
+      case 'batch_0':
+        $messages[] = 'results for batch 0<br />none';
+        break;
+
+      case 'batch_1':
+        $messages[] = 'results for batch 1<br />op 1: processed 10 elements';
+        break;
+
+      case 'batch_2':
+        $messages[] = 'results for batch 2<br />op 2: processed 10 elements';
+        break;
+
+      case 'batch_3':
+        $messages[] = 'results for batch 3<br />op 1: processed 10 elements<br />op 2: processed 10 elements';
+        break;
+
+      case 'batch_4':
+        $messages[] = 'results for batch 4<br />op 1: processed 10 elements';
+        $messages = array_merge($messages, $this->_resultMessages('batch_2'));
+        break;
+
+      case 'chained':
+        $messages = array_merge($messages, $this->_resultMessages('batch_1'));
+        $messages = array_merge($messages, $this->_resultMessages('batch_2'));
+        $messages = array_merge($messages, $this->_resultMessages('batch_3'));
+        break;
+    }
+    return $messages;
+  }
+}
+
+/**
+ * Tests for the Batch API Progress page.
+ */
+class BatchPageTestCase extends DrupalWebTestCase {
+  public static function getInfo() {
+    return array(
+      'name' => 'Batch progress page',
+      'description' => 'Test the content of the progress page.',
+      'group' => 'Batch API',
+    );
+  }
+
+  function setUp() {
+    parent::setUp('batch_test');
   }
 
   /**
    * Tests that the batch API progress page uses the correct theme.
    */
-  function testBatchAPIProgressPageTheme() {
+  function testBatchProgressPageTheme() {
+    // Make sure that the page which starts the batch (an administrative page)
+    // is using a different theme than would normally be used by the batch API.
+    variable_set('theme_default', 'garland');
+    variable_set('admin_theme', 'seven');
     // Visit an administrative page that runs a test batch, and check that the
     // theme that was used during batch execution (which the batch callback
     // function saved as a variable) matches the theme used on the
     // administrative page.
-    $this->drupalGet('admin/system-test/batch-theme');
-    $batch_theme_used = variable_get('system_test_batch_theme_used', 'garland');
-    $this->assertEqual($batch_theme_used, 'seven', t('A progressive batch correctly uses the theme of the page that started the batch.'));
+    $this->drupalGet('admin/batch_test/test_theme');
+    // The stack should contain the name of the the used on the progress page.
+    $this->assertEqual(batch_test_stack(), array('seven'), t('A progressive batch correctly uses the theme of the page that started the batch.'));
   }
 }
 
@@ -44,13 +290,13 @@ class BatchAPIThemeTestCase extends DrupalWebTestCase {
  * Tests the function _batch_api_percentage() to make sure that the rounding
  * works properly in all cases.
  */
-class BatchAPIPercentagesTestCase extends DrupalWebTestCase {
+class BatchPercentagesUnitTestCase extends DrupalUnitTestCase {
   protected $testCases = array();
 
   public static function getInfo() {
     return array(
-      'name' => 'Batch API percentages',
-      'description' => 'Tests the handling of percentage rounding in the Drupal batch API. This is critical to Drupal user experience.',
+      'name' => 'Batch percentages',
+      'description' => 'Unit tests of progress percentage rounding.',
       'group' => 'Batch API',
     );
   }
@@ -99,10 +345,9 @@ class BatchAPIPercentagesTestCase extends DrupalWebTestCase {
   }
 
   /**
-   * Test the _batch_api_percentage() function with the data stored in the
-   * testCases class variable.
+   * Test the _batch_api_percentage() function.
    */
-  function testBatchAPIPercentages() {
+  function testBatchPercentages() {
     require_once DRUPAL_ROOT . '/includes/batch.inc';
     foreach ($this->testCases as $expected_result => $arguments) {
       // PHP sometimes casts numeric strings that are array keys to integers,
diff --git modules/simpletest/tests/form.test modules/simpletest/tests/form.test
index 1971cc8..a6b7c9e 100644
--- modules/simpletest/tests/form.test
+++ modules/simpletest/tests/form.test
@@ -512,45 +512,6 @@ class FormsElementsTableSelectFunctionalTest extends DrupalWebTestCase {
 }
 
 /**
- * Test using drupal_form_submit in a batch.
- */
-class FormAPITestCase extends DrupalWebTestCase {
-
-  public static function getInfo() {
-    return array(
-      'name' => 'Drupal Execute and Batch API',
-      'description' => 'Tests the compatibility of drupal_form_submit and the Batch API',
-      'group' => 'Form API',
-    );
-  }
-
-  /**
-   * Check that we can run drupal_form_submit during a batch.
-   */
-  function testDrupalFormSubmitInBatch() {
-
-    // Our test is going to modify the following variable.
-    variable_set('form_test_mock_submit', 'initial_state');
-
-    // This is a page that sets a batch, which calls drupal_form_submit, which
-    // modifies the variable we set up above.
-    $this->drupalGet('form_test/drupal_form_submit_batch_api');
-
-    // If the drupal_form_submit call executed correctly our test variable will be
-    // set to 'form_submitted'.
-    $this->assertEqual('form_submitted', variable_get('form_test_mock_submit', 'initial_state'), t('Check drupal_form_submit called submit handlers when running in a batch'));
-
-    // Clean our variable up.
-    variable_del('form_test_mock_submit');
-  }
-
-  function setUp() {
-    parent::setUp('form_test');
-  }
-
-}
-
-/**
  * Test the form storage on a multistep form.
  *
  * The tested form puts data into the storage during the initial form
diff --git modules/simpletest/tests/form_test.module modules/simpletest/tests/form_test.module
index 004a3fd..0c3e4e5 100644
--- modules/simpletest/tests/form_test.module
+++ modules/simpletest/tests/form_test.module
@@ -54,13 +54,6 @@ function form_test_menu() {
     'type' => MENU_CALLBACK,
   );
 
-  $items['form_test/drupal_form_submit_batch_api'] = array(
-    'title' => 'BatchAPI Drupal_form_submit tests',
-    'page callback' => 'form_test_drupal_form_submit_batch_api',
-    'access arguments' => array('access content'),
-    'type' => MENU_CALLBACK,
-  );
-
   $items['form_test/form-storage'] = array(
     'title' => 'Form storage test',
     'page callback' => 'drupal_get_form',
@@ -376,67 +369,6 @@ function _form_test_tableselect_js_select_form($form, $form_state, $action) {
 }
 
 /**
- * Page callback for the batch/drupal_form_submit interaction test.
- *
- * When called without any arguments we set up a batch that calls
- * form_test_batch_callback. That function will submit a form using
- * drupal_form_submit using the values specified in this function.
- *
- * The form's field test_value begins at 'initial_value', and is changed
- * to 'form_submitted' when the form is submitted successfully. On
- * completion this function is passed 'done' to complete the process.
- */
-function form_test_drupal_form_submit_batch_api($arg = '') {
-  // If we're at the end of the batch process, return.
-  if ($arg == 'done') {
-    return t('Done');
-  }
-
-  // Otherwise set up the batch.
-  $batch['operations'] = array(
-    array('form_test_batch_callback', array('form_submitted')),
-  );
-
-  // Set the batch and process it.
-  batch_set($batch);
-  batch_process('form_test/drupal_form_submit_batch_api/done');
-}
-
-/**
- * Submits form_test_mock_form using drupal_form_submit using the given $value.
- */
-function form_test_batch_callback($value) {
-  $state['values']['test_value'] = $value;
-  drupal_form_submit('form_test_mock_form', $state);
-}
-
-/**
- * A simple form with a textfield and submit button.
- */
-function form_test_mock_form($form, $form_state) {
-  $form['test_value'] = array(
-    '#type' => 'textfield',
-    '#default_value' => 'initial_state',
-  );
-
-  $form['submit'] = array(
-    '#type' => 'submit',
-    '#value' => t('Submit'),
-  );
-
-  return $form;
-}
-
-/**
- * Form submission callback.
- *
- * Updates the variable 'form_test_mock_submit' to the submitted form value.
- */
-function form_test_mock_form_submit($form, &$form_state) {
-  variable_set('form_test_mock_submit', $form_state['values']['test_value']);
-}
-
-/**
  * A multistep form for testing the form storage.
  *
  * It uses two steps for editing a virtual "thing". Any changes to it are saved
diff --git modules/simpletest/tests/system_test.module modules/simpletest/tests/system_test.module
index 8d1ab9f..af5a039 100644
--- modules/simpletest/tests/system_test.module
+++ modules/simpletest/tests/system_test.module
@@ -5,11 +5,6 @@
  * Implements hook_menu().
  */
 function system_test_menu() {
-  $items['admin/system-test/batch-theme'] = array(
-    'page callback' => 'system_test_batch_theme',
-    'access callback' => TRUE,
-    'type' => MENU_CALLBACK,
-  );
   $items['system-test/sleep/%'] = array(
     'page callback' => 'system_test_sleep',
     'page arguments' => array(2),
@@ -102,34 +97,6 @@ function system_test_menu() {
   return $items;
 }
 
-/**
- * Menu callback; start a new batch for testing the batch progress page theme.
- */
-function system_test_batch_theme() {
-  $batch = array(
-    'operations' => array(
-      array('system_test_batch_theme_callback', array()),
-    ),
-  );
-  batch_set($batch);
-  // Force the batch to redirect to some page other than this one (to avoid an
-  // infinite loop).
-  batch_process('node');
-}
-
-/**
- * Batch callback function for testing the theme used by a batch.
- */
-function system_test_batch_theme_callback() {
-  // Because drupalGet() steps through the full progressive batch before
-  // returning control to the test function, we cannot test that the correct
-  // theme is being used on the batch processing page by viewing that page
-  // directly. Instead, we save the theme being used in a variable here, so
-  // that it can be loaded and inspected in the thread running the test.
-  global $theme;
-  variable_set('system_test_batch_theme_used', $theme);
-}
-
 function system_test_sleep($seconds) {
   sleep($seconds);
 }
diff --git modules/system/system.install modules/system/system.install
index 9594c88..52b0f59 100644
--- modules/system/system.install
+++ modules/system/system.install
@@ -496,7 +496,9 @@ function system_schema() {
     'fields' => array(
       'bid' => array(
         'description' => 'Primary Key: Unique batch ID.',
-        'type' => 'serial',
+        // This is not a serial column, to allow both progressive and
+        // non-progressive batches. See batch_process().
+        'type' => 'int',
         'unsigned' => TRUE,
         'not null' => TRUE,
       ),
@@ -2257,50 +2259,7 @@ function system_update_7021() {
  * Add the queue tables.
  */
 function system_update_7022() {
-  $schema['queue'] = array(
-    'description' => 'Stores items in queues.',
-    'fields' => array(
-      'item_id' => array(
-        'type' => 'serial',
-        'unsigned' => TRUE,
-        'not null' => TRUE,
-        'description' => 'Primary Key: Unique item ID.',
-      ),
-      'name' => array(
-        'type' => 'varchar',
-        'length' => 255,
-        'not null' => TRUE,
-        'default' => '',
-        'description' => 'The queue name.',
-      ),
-      'data' => array(
-        'type' => 'text',
-        'not null' => FALSE,
-        'size' => 'big',
-        'serialize' => TRUE,
-        'description' => 'The arbitrary data for the item.',
-      ),
-      'expire' => array(
-        'type' => 'int',
-        'not null' => TRUE,
-        'default' => 0,
-        'description' => 'Timestamp when the claim lease expires on the item.',
-      ),
-      'created' => array(
-        'type' => 'int',
-        'not null' => TRUE,
-        'default' => 0,
-        'description' => 'Timestamp when the item was created.',
-      ),
-    ),
-    'primary key' => array('item_id'),
-    'indexes' => array(
-      'name_created' => array('name', 'created'),
-      'expire' => array('expire'),
-    ),
-  );
-
-  db_create_table('queue', $schema['queue']);
+  // Moved to update_fix_d7_requirements().
 }
 
 /**
@@ -2728,6 +2687,13 @@ function system_update_7049() {
 }
 
 /**
+ * Change {batch}.id column from serial to regular int.
+ */
+function system_update_7050() {
+  db_change_field('batch', 'bid', 'bid', array('description' => 'Primary Key: Unique batch ID.', 'type' => 'int', 'unsigned' => TRUE, 'not null' => TRUE));
+}
+
+/**
  * @} End of "defgroup updates-6.x-to-7.x"
  * The next series of updates should start at 8000.
  */
diff --git modules/system/system.module modules/system/system.module
index 3a21585..36fad69 100644
--- modules/system/system.module
+++ modules/system/system.module
@@ -2690,10 +2690,6 @@ function system_cron() {
   db_delete('flood')
     ->condition('expiration', REQUEST_TIME, '<')
     ->execute();
-  // Cleanup the batch table.
-  db_delete('batch')
-    ->condition('timestamp', REQUEST_TIME - 864000, '<')
-    ->execute();
 
   // Remove temporary files that are older than DRUPAL_MAXIMUM_TEMP_FILE_AGE.
   // Use separate placeholders for the status to avoid a bug in some versions
@@ -2717,6 +2713,15 @@ function system_cron() {
     cache_clear_all(NULL, $table);
   }
 
+  // Cleanup the batch table and the queue for failed batches.
+  db_delete('batch')
+    ->condition('timestamp', REQUEST_TIME - 864000, '<')
+    ->execute();
+  db_delete('queue')
+    ->condition('created', REQUEST_TIME - 864000, '<')
+    ->condition('name', 'drupal_batch:%', 'LIKE')
+    ->execute();
+
   // Reset expired items in the default queue implementation table. If that's
   // not used, this will simply be a no-op.
   db_update('queue')
diff --git modules/system/system.queue.inc modules/system/system.queue.inc
index 2342b78..9ab3503 100644
--- modules/system/system.queue.inc
+++ modules/system/system.queue.inc
@@ -254,5 +254,78 @@ class SystemQueue implements DrupalQueueInterface {
 }
 
 /**
+ * Static queue implementation.
+ *
+ * This allows "undelayed" variants of processes relying on the Queue
+ * interface. The queue data resides in memory. It should only be used for
+ * items that will be queued and dequeued within a given page request.
+ */
+class MemoryQueue implements DrupalQueueInterface {
+  /**
+   * The queue data.
+   *
+   * @var array
+   */
+  protected $queue;
+
+  /**
+   * Counter for item ids.
+   *
+   * @var int
+   */
+  protected $id_sequence;
+
+  public function __construct($name) {
+    $this->queue = array();
+    $this->id_sequence = 0;
+  }
+
+  public function createItem($data) {
+    $item = new stdClass();
+    $item->item_id = $this->id_sequence++;
+    $item->data = $data;
+    $item->created = time();
+    $item->expire = 0;
+    $this->queue[$item->item_id] = $item;
+  }
+
+  public function numberOfItems() {
+    return count($this->queue);
+  }
+
+  public function claimItem($lease_time = 30) {
+    foreach ($this->queue as $key => $item) {
+      if ($item->expire == 0) {
+        $item->expire = time() + $lease_time;
+        $this->queue[$key] = $item;
+        return $item;
+      }
+    }
+    return FALSE;
+  }
+
+  public function deleteItem($item) {
+    unset($this->queue[$item->item_id]);
+  }
+
+  public function releaseItem($item) {
+    if (isset($this->queue[$item->item_id]) && $this->queue[$item->item_id]->expire != 0) {
+      $this->queue[$item->item_id]->expire = 0;
+      return TRUE;
+    }
+    return FALSE;
+  }
+
+  public function createQueue() {
+    // Nothing needed here.
+  }
+
+  public function deleteQueue() {
+    $this->queue = array();
+    $this->id_sequence = 0;
+  }
+}
+
+/**
  * @} End of "defgroup queue".
  */