Observing Node.js

Explore tools and techniques for observing and understanding the inner workings of Node.js processes in this conference talk from CascadiaJS 2018. Dive into four critical concepts including the microtask queue, event loop, and JavaScript execution. Learn about event loop delay, the bootstrap process, and main event loop. Discover the first rule of Node.js performance and gain insights into async hooks, bubble profiling, and bootstrap trace events. Examine tricky questions about Promises and their execution, enhancing your understanding of Node.js internals and improving your ability to optimize application performance.

Observing Node.js James Snell
What's happening inside?
Your Challenge: In what order will the statements be printed?
Four Critical Concepts
The Microtask Queue
The event loop executes only one task at a time.
When JavaScript is running the Event Loop is not
Event Loop Delay
JavaScript is not asynchronous.
Bootstrap » Main Event Loop
Bootstrap: Node.js loads it's own JavaScript...
Main: Node.js loads and executes user code...
Event Loop: Started after main scope exits...
First Rule of Node.js Performance: Know when your code is running
Async Hooks
Bubble Profiling
Bootstrap Trace Events
Trick Question: Are Promises Asynchronous?
Trick Question: Do Promises execute concurrently?