Node.js event loop
Christopher Kade
Inspired by James Snell's talk at CascadiaJS 2018
@christo_kade
What's the point of this presentation?
Understanding precisely how this part of Node works
Debugging efficiently my Node projects
Two parts:
- Summing-up the Event Loop
- The Event Loop's architecture
Summing-up the Event Loop
The Event Loop executes only one task at a time
Event Loop
C++
Javascript
Event Loop notification
NTQ
MTQ
process.nextTick(callback)
.then()
.catch()
.finally()
When Javascript is running, the Event Loop is not
a.k.a the Event Loop Delay
The Event Loop's architecture
setTimeout(callback)
setInterval(callback)
Accepting new connections & data related calls
Callbacks linked to closing of sockets etc.
Things to remember:
-
The Event Loop executes only one task at a time
-
When Javascript is running, the Event Loop is not (both on a single thread)
-
The Event Loop is composed of more than one queue (or queue-like structure)
Thank you for your attention !
References:
Node.js event loop workflow & lifecycle in low level - http://voidcanvas.com/nodejs-event-loop/
Observing NodeJS - https://www.youtube.com/watch?v=V0LcfB-H0aY&t=