Neos\Media\Command\MediaCommandController::renderThumbnailsCommand PHP Method

    public function renderThumbnailsCommand($limit = null)
    {
        $thumbnailCount = $this->thumbnailRepository->countUngenerated();
        $iterator = $this->thumbnailRepository->findUngeneratedIterator();
        $this->output->progressStart($limit !== null && $thumbnailCount > $limit ? $limit : $thumbnailCount);
        $iteration = 0;
        foreach ($this->thumbnailRepository->iterate($iterator) as $thumbnail) {
            if ($thumbnail->getResource() === null) {
                $this->thumbnailService->refreshThumbnail($thumbnail);
                $this->persistenceManager->persistAll();
            }
            $this->output->progressAdvance(1);
            $iteration++;
            if ($iteration === $limit) {
                break;
            }
        }
    }