Node.js Q & A


Is Node.js single-threaded or multi-threaded?

Node.js operates on a single-threaded event loop architecture. This means that it runs on a single thread, executing all JavaScript code in a non-blocking manner. While this might sound limiting, it’s actually quite efficient for handling I/O-bound operations.


In a single-threaded model, all I/O operations, such as file system operations, network requests, and database queries, are handled asynchronously. When an I/O operation is initiated, Node.js doesn’t wait for it to complete. Instead, it continues executing other tasks. Once the I/O operation is finished, a callback function is triggered to handle the result.


While Node.js itself is single-threaded, it can leverage multi-threading through worker threads for CPU-bound tasks. This allows developers to offload heavy computational tasks to separate threads, keeping the main event loop free to handle I/O operations.

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Experienced Principal Engineer and Fullstack Developer with a strong focus on Node.js. Over 5 years of Node.js development experience.