Understanding Nginx Architecture: Master and Worker Processes, Workflow, and Key Features

Nginx is a high‑performance open‑source web server commonly used as a reverse proxy, load balancer, and HTTP cache.

Thanks to its event‑driven architecture and modular design, Nginx offers high concurrency, high performance, and low resource consumption, making it a staple in modern web systems.

Nginx Architecture

Nginx follows a multi‑process model, which is a key factor of its performance.

It consists of a single Master Process and multiple Worker Processes.

Master Process

The Master Process manages the worker processes and handles tasks such as loading and validating the configuration file (nginx.conf), creating, starting, stopping, and restarting workers, receiving and distributing OS signals, and monitoring worker health to ensure service stability.

Load and validate configuration: reads and checks nginx.conf at startup.

Manage worker processes: creates, starts, stops, and restarts them.

Receive and dispatch signals: handles OS signals (e.g., reload, stop) and forwards them to workers.

Monitor workers: restarts any worker that exits unexpectedly.

Worker Processes

Worker Processes handle actual client requests; each runs independently and can process thousands of connections concurrently using an asynchronous, non‑blocking model.

Handle client requests: process connections and HTTP requests.

Independent operation: a crash in one worker does not affect others.

Asynchronous non‑blocking: enables high concurrency.

Nginx Request Flow

The processing steps are:

Receive request: Nginx accepts the client connection.

Parse request: it parses the request line and headers.

Find configuration: selects the appropriate configuration based on the request URL.

Process request: performs actions such as proxying, caching, or serving static files according to the configuration.

Send response: returns the generated response to the client.

Log: records request and response details.

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