Unlock Nginx’s High‑Concurrency Secrets: Master‑Worker, Event‑Driven & Epoll Explained

Nginx (Engine‑X) is a high‑performance HTTP server and load balancer widely used in the Internet industry.

The efficiency of Nginx stems from a simple Master‑Worker process model: the master process parses configuration files, creates and manages worker processes, and handles signals, while each worker process independently handles many concurrent connections.

The worker processes are event‑driven, using non‑blocking I/O and Linux epoll (or similar I/O multiplexing) to monitor thousands of file descriptors without spawning a thread per connection.

When a request arrives, Nginx adds it to an event queue and immediately continues processing other requests; once the request is completed, it is retrieved from the queue for further handling, avoiding blocking I/O.

Beyond these core techniques, Nginx also employs caching static content, reverse‑proxying responses, and Gzip compression to reduce backend load and network traffic, further boosting performance for high‑concurrency scenarios.