hard20 pts · first answer countsnodejsconcurrencyperformance

One slow route freezes Node.js

In a Node.js API, one endpoint resizes images using a synchronous pure-JavaScript loop that takes 2 seconds. During that time all other requests, even health checks, hang. Why, and what is the right fix?

A.Node.js creates one thread per request, and the OS limits threads; increase ulimitB.The database pool is exhausted; add more connectionsC.Express handles only one route at a time; switch to FastifyD.CPU-bound sync code blocks the single event loop thread; move it to worker_threads, a job queue or a native async library

← Saving to DB and publishing an event Connection pools and autoscaling →