Building a Polite and Fast Web Crawler: Lessons Learned
2025-01-05
Mozilla engineer Dennis Schubert found that 70% of Diaspora's server load stemmed from poorly-behaved bots, with OpenAI and Amazon contributing 40%. This article details the author's experience building a polite and fast web crawler, covering rate limiting, respecting robots.txt, minimizing refetching, and efficient enqueuing. Using Python and gevent, the author assigns a coroutine per domain for rate limiting and leverages Postgres for efficient queue management and deduplication. This design allows for fast and efficient crawling while respecting target websites.