7 minute read In the first post of this series, I outlined Shopify’s history with flash sales, our move to Nginx and Lua to help manage traffic, and the initial attempt we made to throttle traffic that didn’t account sufficiently for customer experience. We had underestimated the impact of not giving preference to customers who’d entered the queue at the beginning of the sale, and now we needed to find another way to protect the platform without ruining the customer experience.