Systems · Week 3
Week 3: Edge, media, and counters
Load balancers, leaders, CDN media, upload pipelines, private media, hot counters.
Week 3: Edge, media, and counters
Load balancers, leaders, CDN media, upload pipelines, private media, hot counters.
Outcomes
- Explain the failure drill for each lesson in this week without notes.
- Complete linked labs where present and keep a short metric log.
- Tag each system with the pattern cards you actually used.
- CDN for live and near-live media Cache hierarchies, signed paths, and origin shield patterns for media.
- Leader election for reads When a leader helps, when quorum reads are safer, and how fencing applies.
- Scalable load balancer thinking Health, slow starts, and avoiding thundering herds onto cold instances.
- Hashtag counters Hot keys, approximate counts, and shard tactics for viral tags.
- Photo upload pipeline Direct-to-store uploads, async processing, and durable intents.
- Private media and avatars Authorization at the URL layer without turning the API into a bytes proxy.