Sunday, September 27, 2015

order of event queue in Node.JS event loop

I was reading the book "Node.JS in Practice", in Chapter 2, Technique 14, it talks about the order of scheduling I/O events, setImmediate, setTimeout/setInterval and process.nextTick. Like in the following screenshot from the book:

However, it seem that the ordering is a bit different, from my test, it is more like: process.nextTick, setTimeout/setInterval, setImmediate.

Here is the sample test code and result (Node.JS v4.1.0):

setImmediate(function() {
    console.log("from setImmediate");

setTimeout(function() {
    console.log("from setTimeout");
}, 10);

process.nextTick(function() {
    console.log("from process.nextTick");


from process.nextTick
from setTimeout
from setImmediate