The One-Second Surge: Debugging a Billion-Device Edge Case at Google with Jay Gengelbach

In this episode, Jay Gengelbach, longtime Engineer at Alphabet and current Software Engineer at Vercel breaks down the story of a hard-to-track-down bug he encountered: a mysterious spike in server errors that hit exactly at the top of every hour (and other “round” time boundaries) across Google Now/Discover’s massive mobile footprint. Jay walks through how the team traced it to battery-saver behavior on certain devices/apps that effectively rationed background connectivity, causing synchronized bursts of requests the infrastructure couldn’t react to in time. The fix wasn’t just “handle more load,” but reshape it: using server-controlled scheduling to create intentional “load divots” so misbehaving clients could spike into empty space. The conversation wraps with Jay’s current work at Vercel scaling CI/CD reliability and speed, plus a measured take on AI: real value, real hype, and a looming reckoning when “free” stops being free.