Regenerate PrestaShop thumbnails without timeouts or missing images

• Short cycles: a few seconds of work (5 by default), a pause (half a second), then the next cycle. No timeouts, and the site stays fast for customers.
• No missing images: each thumbnail is created in a temporary file and replaces the old one only when it’s ready. During a full regeneration we ran 67 million checks: 0 missing thumbnails.
• Only what’s needed: by default it skips thumbnails that already exist and are newer than the original; a second pass over 323 images takes 2 seconds.
• In the background: you can close the page or the browser and do something else. If the chain breaks, for example because the server restarts, it resumes the next time the back office is opened.
• Pause, resume and cancel whenever you like; reopening the page shows the progress.
• Errors explained, without stopping: missing or corrupt original, image too large for PHP memory (checked before processing, so PHP doesn’t crash).
• An email when it finishes, or if something goes wrong, with a summary and the list of images with problems.
• Optional cron as a safety net, with the line to add already prepared.

If the shop is still slow once the images are sorted, the server may be the problem: see Flag’s managed PrestaShop hosting or read how to choose a PrestaShop server.