The 58-Million-Key Freeze: What a HashMap Resize Taught Us About Memory Allocation at Scale (10 minute read) (opens in new tab)

LinkedIn's Feed is the central experience for over a billion members - it's where they discover relevant content, engage with their network, and stay informed. Behind the scenes, serving the Feed depends on a chain of infrastructure components that must respond reliably in milliseconds. When one of those components starts freezing for 15 seconds at a time, the Feed experience for members is degraded. That’s exactly what we saw happen.