$myFeed->startImport()

public function startImport() {
    module_invoke_all('feeds_before_import', $this);
    $config = $this->importer->getConfig();
    if ($config['process_in_background']) {
      $this->startBackgroundJob('import');
    }
    else {
      $this->startBatchAPIJob(t('Importing'), 'import');
    }
}

/**
   * Background job helper. Starts a background job using Job Scheduler.
   *
   * Execute the first batch chunk of a background job on the current page load,
   * moves the rest of the job processing to a cron powered background job.
   *
   * Executing the first batch chunk is important, otherwise, when a user
   * submits a source for import or clearing, we will leave her without any
   * visual indicators of an ongoing job.
   *
   * @see FeedsSource::startImport().
   * @see FeedsSource::startClear().
   *
   * @param $method
   *   Method to execute on importer; one of 'import' or 'clear'.
   *
   * @throws Exception $e
   */
  protected function startBackgroundJob($method) {
    if (FEEDS_BATCH_COMPLETE != $this->$method()) {
      $job = array(
        'type' => $this->id,
        'id' => $this->feed_nid,
        'period' => 0,
        'periodic' => FALSE,
      );
      JobScheduler::get("feeds_source_{$method}")->set($job);
    }
  }