When is NodeJS Single-Threaded and when is it Multi-Threaded?

Node JS Is single threaded asynchronous non-blocking javascript runtime, but its not always single threaded there are occasions where nodejs uses multi-threading, so the questions we will try to answer in this video, when is nodejs single threaded and when does it use multi-threading and how will that affect my app? Event main Loop 0:00 single thread, that really just loops for callbacks Threading in Node jS (libuv) 4:00 used for IO/intensive DNS queries file system reads CPU intensive crypto compression process.env.UV_THREADPOOL_SIZE=1 Examples 8:00 Cluster Nodejs 16:00 Example 1 Http server return 1 Http server while 1 Http server with file system read async Http server with file system read sync Http server with fetch call to server (dns) Resources https://nodejs.org/en/docs/guides/don... http://docs.libuv.org/en/v1.x/index.html 🎙️Listen to the Backend Engineering Podcast https://husseinnasser.com/podcast 🏭 Backend Engineering Videos https://backend.husseinnasser.com 💾 Database Engineering Videos    • Database Engineering   🏰 Load Balancing and Proxies Videos    • Proxies   🏛️ Software Archtiecture Videos    • Software Architecture   📩 Messaging Systems    • Message Queues & PubSub Systems   Become a Member    / @hnasr   Support me on PayPal https://bit.ly/33ENps4 Stay Awesome, Hussein

What the heck is the event loop anyway? | Philip Roberts | JSConf EU
▶︎

What the heck is the event loop anyway? | Philip Roberts | JSConf EU

Browser Caching Best Practices,  When to use no-cache vs max-age without breaking your site
▶︎

Browser Caching Best Practices, When to use no-cache vs max-age without breaking your site

Asynchronous vs Multithreading and Multiprocessing Programming (The Main Difference)
▶︎

Asynchronous vs Multithreading and Multiprocessing Programming (The Main Difference)

Zig 2026: No-AI Policy, $670K Foundation, Left GitHub & Why Zig Isn’t 1.0 - Andrew Kelley Explains
▶︎

Zig 2026: No-AI Policy, $670K Foundation, Left GitHub & Why Zig Isn’t 1.0 - Andrew Kelley Explains

WebSockets Crash Course - Handshake, Use-cases, Pros & Cons and more
▶︎

WebSockets Crash Course - Handshake, Use-cases, Pros & Cons and more

PROOF JavaScript is a Multi-Threaded language
▶︎

PROOF JavaScript is a Multi-Threaded language

The Node.js Event Loop: Not So Single Threaded
▶︎

The Node.js Event Loop: Not So Single Threaded

What are web servers and how do they work (with examples httpd and nodejs)
▶︎

What are web servers and how do they work (with examples httpd and nodejs)

gRPC Crash Course - Modes, Examples, Pros & Cons and more
▶︎

gRPC Crash Course - Modes, Examples, Pros & Cons and more

What is a Message Queue and When should you use Messaging Queue Systems Like RabbitMQ and Kafka
▶︎

What is a Message Queue and When should you use Messaging Queue Systems Like RabbitMQ and Kafka

Jake Archibald on the web browser event loop, setTimeout, micro tasks, requestAnimationFrame, ...
▶︎

Jake Archibald on the web browser event loop, setTimeout, micro tasks, requestAnimationFrame, ...

The Insane Genius of a Formula 1 Gearbox
▶︎

The Insane Genius of a Formula 1 Gearbox

I Predicted This War. Here Is Exactly What Happens Next - Professor Jiang
▶︎

I Predicted This War. Here Is Exactly What Happens Next - Professor Jiang

JavaScript Visualized - Event Loop, Web APIs, (Micro)task Queue
▶︎

JavaScript Visualized - Event Loop, Web APIs, (Micro)task Queue

How to use Multithreading with "worker threads" in Node.js?
▶︎

How to use Multithreading with "worker threads" in Node.js?

99% of Developers Don't Get Sockets
▶︎

99% of Developers Don't Get Sockets

Turing Award Winner: Disagreeing with Google, Postgres, Future Problems | Mike Stonebraker
▶︎

Turing Award Winner: Disagreeing with Google, Postgres, Future Problems | Mike Stonebraker

The OSI Model by Example - The Backend Engineering Show with Hussein Nasser
▶︎

The OSI Model by Example - The Backend Engineering Show with Hussein Nasser

Scaling Websockets with Redis, HAProxy and Node JS - High-availability Group Chat Application
▶︎

Scaling Websockets with Redis, HAProxy and Node JS - High-availability Group Chat Application

Trump Brags About His Brain, Crowd Size & Pool, CBS Fires Scott Pelley & Don Jr's Honeymoon Video
▶︎

Trump Brags About His Brain, Crowd Size & Pool, CBS Fires Scott Pelley & Don Jr's Honeymoon Video