Design Distributed Web Crawler (Google Search) (Variant #22 - Geospatial & Location Dispatch)
Complete FAANG-level system design blueprint for Distributed Web Crawler (Google Search). Covers capacity estimation, high-level architecture, deep-dive components, database schemas, and distributed failure modes.
Functional Requirements
- •Core functional capability: Crawl billions of web pages across the internet, parse links, and index content
- •Provide real-time telemetry, monitoring, and audit logging
- •Ensure idempotent operations with zero duplicate executions
Non-Functional Requirements
- •Strict non-functional SLA: Politeness delay, high throughput, robust deduplication
- •High availability (99.999% uptime with zero single points of failure)
- •Horizontally scalable architecture with auto-scaling compute pools
Capacity & Scale Estimation
Core Architectural Components
1Client Layer & API Gateway
Handles TLS termination, JWT authentication, rate limiting, and reverse proxy routing to internal microservices.
2Primary Ingestion & Business Service
Executes core business logic for crawl billions of web pages across the internet, parse links, and index content with strict validation bounds.
3Distributed Caching & In-Memory State
Multi-tier Redis cluster caching hot keys to achieve sub-millisecond p99 response times.
4Asynchronous Message Queue & Stream Buffer
Kafka cluster decoupling heavy write loads, facilitating event-driven processing and retry dead-letter queues.
5Persistent Storage & Data Tier
Partitioned SQL / NoSQL database with read replicas, sharded by primary entity ID for horizontal scaling.
Architectural FAQs & Interview Deep Dives
How does this Distributed Web Crawler (Google Search) architecture handle sudden traffic spikes?
Traffic spikes are buffered using distributed Kafka message queues and elastic auto-scaling worker groups, while read requests are absorbed by multi-tier Redis caches.
How do you prevent data inconsistencies during network partition failures?
We enforce the CAP theorem trade-offs using Quorum-based Raft consensus for strong consistency or Eventual Consistency with vector clocks for high availability.
What is the single most common failure mode in Distributed Web Crawler (Google Search)?
Cascading failures caused by unhandled downstream timeouts. We mitigate this using Circuit Breakers with exponential backoff and jittered retries.