Neos\Media\Domain\Repository\AssetRepository::findAllIterator PHP Method

    public function findAllIterator()
    {
        /** @var QueryBuilder $queryBuilder */
        $queryBuilder = $this->entityManager->createQueryBuilder();
        return $queryBuilder->select('a')->from($this->getEntityClassName(), 'a')->where('a NOT INSTANCE OF Neos\\Media\\Domain\\Model\\ImageVariant')->getQuery()->iterate();
    }

 /**
  * Create thumbnails
  *
  * Creates thumbnail images based on the configured thumbnail presets. Optional ``preset`` parameter to only create
  * thumbnails for a specific thumbnail preset configuration.
  *
  * Additionally accepts a ``async`` parameter determining if the created thumbnails are generated when created.
  *
  * @param string $preset Preset name, if not provided thumbnails are created for all presets
  * @param boolean $async Asynchronous generation, if not provided the setting ``Neos.Media.asyncThumbnails`` is used
  * @return void
  */
 public function createThumbnailsCommand($preset = null, $async = null)
 {
     $async = $async !== null ? $async : $this->asyncThumbnails;
     $presets = $preset !== null ? [$preset] : array_keys($this->thumbnailService->getPresets());
     $presetThumbnailConfigurations = [];
     foreach ($presets as $preset) {
         $presetThumbnailConfigurations[] = $this->thumbnailService->getThumbnailConfigurationForPreset($preset, $async);
     }
     $iterator = $this->assetRepository->findAllIterator();
     $imageCount = $this->assetRepository->countAll();
     $this->output->progressStart($imageCount * count($presetThumbnailConfigurations));
     foreach ($this->assetRepository->iterate($iterator) as $image) {
         foreach ($presetThumbnailConfigurations as $presetThumbnailConfiguration) {
             $this->thumbnailService->getThumbnail($image, $presetThumbnailConfiguration);
             $this->persistenceManager->persistAll();
             $this->output->progressAdvance(1);
         }
     }
 }