Vercel 推出 ISR 快取未命中請求合併機制（Request Collapsing）

In modern web development, Next.js's Incremental Static Regeneration (ISR) is a critical technique for balancing the speed of statically served pages with the need for dynamic content updates. However, on high-traffic websites, when the cache for a popular page expires (a Cache Miss or Stale state), or when a page is first published, hundreds or even thousands of users may simultaneously send requests. In the past, this could cause multiple concurrent requests to punch through to the backend, triggering multiple redundant page re-generations — a phenomenon in system design known as the "Thundering Herd" effect or cache stampede, which places enormous load on Serverless functions, APIs, and databases while incurring unnecessary costs.