The CTO Podcast with Fexingo · 2026-07-12 · 12 min
In this episode, Lucas and Luna break down how Slack re-architected its real-time messaging layer to handle 10 million concurrent connections. They walk through the migration from a single-room event bus to a sharded, multi-region WebSocket mesh; the decision to decouple presence from message delivery; and the surprising bottleneck that emerged from emoji reactions. Along the way, they discuss tradeoffs around client-side backpressure, the cost of preserving message ordering across shards, and why Slack ultimately chose to write its own load balancer rather than use a commercial alternative. If you're building any kind of real-time system - chat, notifications, live collaboration - this episode has one concrete lesson you can borrow. #Slack #RealTimeMessaging #WebSocket #BackendArchitecture #DistributedSystems #ConcurrentConnections #Scalability #SystemDesign #EngineeringLeadership #CTO #TechPodcast #Infrastructure #EventBus #LoadBalancing #PerformanceEngineering #Business #Technology #FexingoBusiness Keep every episode free: buymeacoffee.com/fexingo
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