System design interview question
Design a Real-time Feed Generation System like LinkedIn's Activity Feed
Design a scalable feed generation system that serves personalized activity feeds to 300M active users with 50K write events per second (new posts, likes, comments, follows). The system must support multiple feed types (home feed, network feed, hashtag feed) with sub-second latency for read requests in multiple geographic regions (US, EU, APAC). Users follow hundreds to thousands of other users, and the feed must rank activities by relevance and recency while handling fanout of a single post to millions of followers. Design for 99.99% availability, sub-500ms p99 latency, and the ability to serve billions of feed impressions daily.
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