Scrapy AutoThrottle & Rate Limiting: Stop Getting Blocked

The author of the text learned the hard way that scraping websites too quickly can result in being blocked by the website. The problem is not what is being scraped, but rather how fast it is being scraped. To avoid getting blocked, it is essential to scrape politely by implementing a delay between requests. The simplest fix is to use the DOWNLOAD_DELAY setting, which waits a specified number of seconds between requests to the same domain. This delay can be randomized to make it more human-like. Another approach is to limit the number of concurrent requests using the CONCURRENT_REQUESTS setting. AutoThrottle is a smart automatic throttling mechanism that adjusts the scraping speed based on server response time, server load, and error rates. It can be enabled in the settings file and configured to start with a specific delay and target concurrency. The author also discusses handling rate limits, including detecting 429 status codes, captchas, and blocked IPs. To handle rate limits, it is essential to retry requests and slow down the scraping speed. The author provides several strategies for throttling, including time-based throttling, respecting robots.txt crawl-delay, and exponential backoff. Combining multiple techniques is also recommended, such as using basic throttling, AutoThrottle, and retrying on rate limits. Monitoring scraping speed is also crucial to ensure that the scraping is not too fast or too slow. The author provides guidelines on when to slow down or speed up the scraping, such as slowing down when getting 429 errors or captchas, and speeding up when scraping large websites or using multiple IPs. The text concludes by emphasizing the importance of being a good internet citizen and scraping responsibly to avoid getting blocked and wasting time. The author also highlights common mistakes to avoid, such as not adding any delay, using the same delay for all sites, and ignoring 429 responses. The text provides a quick reference guide for basic throttling, AutoThrottle, and handling rate limits. Overall, the author emphasizes the importance of scraping politely and responsibly to avoid getting blocked and to ensure a successful scraping experience. By following the guidelines and best practices outlined in the text, scrapers can avoid common mistakes and ensure a reliable and efficient scraping process.