Design web crawler for 1000 devices
Design a Distributed Web Crawler for 1,000 Devices
Design a production-ready web crawler that starts from a single seed URL and scales crawling across approximately 1,000 heterogeneous devices. The crawler must respect robots.txt and per-host politeness constraints, deduplicate URLs and fetched content, and persist both the frontier state and the fetched pages/metadata.
Requirements
- Start from a single seed URL and discover new URLs recursively.
- Distribute crawling tasks across roughly 1,000 devices.
- Address the following key challenges:
- Coordination of work and shared state.
- Load balancing and throttling.
- Fault tolerance and recovery mechanisms.
- Scalability and common follow-up scenarios.
- Assume an internet-scale target with diverse domains and varying network latency.
Deliverables
- High-level architecture diagram and data flow.
- Mechanisms for URL assignment, deduplication, and scheduling.
- Policies for handling
robots.txt, per-host rate limits, and retries. - Storage strategy for the URL frontier and fetched content.
- Specific implementations for coordination, load balancing, fault tolerance, and scaling.
AI interview prep
Core dilemma
Balancing the need for massive, distributed crawling throughput with the strict requirements of respecting website policies (robots.txt, rate limits) and maintaining data integrity (deduplication) across a heterogeneous fleet of devices.
3 tradeoffs and 3 stress tests locked
Interview prep
Unlock the interviewer X-Ray rubric, tradeoff matrix, stress tests, clarifying questions, and key concepts.
Design web crawler for 1000 devices
Design a Distributed Web Crawler for 1,000 Devices
Design a production-ready web crawler that starts from a single seed URL and scales crawling across approximately 1,000 heterogeneous devices. The crawler must respect robots.txt and per-host politeness constraints, deduplicate URLs and fetched content, and persist both the frontier state and the fetched pages/metadata.
Requirements
- Start from a single seed URL and discover new URLs recursively.
- Distribute crawling tasks across roughly 1,000 devices.
- Address the following key challenges:
- Coordination of work and shared state.
- Load balancing and throttling.
- Fault tolerance and recovery mechanisms.
- Scalability and common follow-up scenarios.
- Assume an internet-scale target with diverse domains and varying network latency.
Deliverables
- High-level architecture diagram and data flow.
- Mechanisms for URL assignment, deduplication, and scheduling.
- Policies for handling
robots.txt, per-host rate limits, and retries. - Storage strategy for the URL frontier and fetched content.
- Specific implementations for coordination, load balancing, fault tolerance, and scaling.