- About This Book
- Purpose of the Book
- Background and Inspiration
- Who This Book Is For
- How to Use This Book
- Acknowledgments
- Help and Support
- Chapter 1: Getting Started
- What Does "Node.js is Single-Threaded" Mean?
- Under the Hood: libuv
- Why Understanding the Event Loop Matters
- What Is Next
- Chapter 2: The Call Stack
- In a Nutshell
- The Bottom Line
- Chapter 3: Timers and Scheduling
- setTimeout(callback, delay)
- setImmediate(callback)
- process.nextTick(callback)
- Performance Warning
- The Bottom Line
- Chapter 4: Inside the Event Loop
- Event Loop Phases
- Microtask Queues
- What Happens When Top-level Code Runs
- What Happens When the Event Loop Starts
- Why the Output Is Different on Some Runs
- The Bottom Line
- Chapter 5: Avoiding Event Loop Blocking
- Rule of Thumb
- How Await Interacts with the Event Loop
- CPU-Intensive Synchronous Operations
- Long-Running Loops
- Large Array/Object Processing
- Memory-Intensive Operations
- Synchronous File System Operations
- Parsing Large Files
- Image Processing Operations
- PDF Generation from HTML
- Slow App Startup
- Uncaught Promise Rejections
- Excessive Logging
- Parsing Large Request Body Without Limits
- Unoptimized Database Queries
- Dangerous Regular Expressions
- Ignoring Clustering
- Detecting Event Loop Blocking
- In a Nutshell
- The Bottom Line
Node.js Event Loop
Mastering Concurrency with Asynchronous Patterns and Non-Blocking Design in Node.js
Every Node.js developer uses asynchronous code but only a few truly understand what happens behind the scenes.
This book reveals the internals of the Node.js Event Loop, including microtasks, macrotasks, and concurrency under load.
You'll learn to master performance, scalability, and non-blocking architecture at a level that sets professionals apart.
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About
About the Book
Understand the event loop. Avoid blocking it. Master Node.js.
This book demystifies the core of Node.js — the event loop — teaches you how to use it efficiently and safely in real-world systems.
You'll learn how Node.js schedules work, handles concurrency, and delivers performance from a single thread. More importantly, you'll discover how to avoid event loop blocking — the silent killer of performance in production.
Inside the book:
- How Node.js handles concurrency with a single thread
- The real differences between setTimeout, setImmediate, and process.nextTick
- How each event loop phase works and what code runs when
- Why non-blocking doesn't always mean fast
- How to design resilient, efficient backend architectures
- Proven techniques for avoiding event loop blocking under real workloads
Who this book is for:
- Intermediate JavaScript developers leveling up to backend Node.js
- Backend engineers who want to understand performance bottlenecks
- Educators or mentors teaching how the Node.js runtime really works
- Anyone who wants to master async behavior and concurrency in Node.js
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