What do the return values of node.js process.memoryUsage() stand for?

Question

From the official documentation (source):

process.memoryUsage()

Returns an object describing the memory usage of the Node

Answer 1

Let's do this with an Example

The following example will show you how the increase in memory usage will actually increase the rss and heapTotal

const numeral = require('numeral');
let m = new Map();
for (let i = 0; i < 100000; i++) {
    m.set(i, i);
    if (i % 10000 === 0) { 
        const { rss, heapTotal } = process.memoryUsage();
        console.log( 'rss', numeral(rss).format('0.0 ib'), heapTotal, numeral(heapTotal).format('0.0 ib') )
    } 
}

Running The above will give you something like this:

rss 22.3 MiB 4734976 4.5 MiB
rss 24.2 MiB 6483968 6.2 MiB
rss 27.6 MiB 9580544 9.1 MiB
rss 27.6 MiB 9580544 9.1 MiB
rss 29.3 MiB 11419648 10.9 MiB
rss 29.3 MiB 11419648 10.9 MiB
rss 29.3 MiB 11419648 10.9 MiB
rss 32.8 MiB 15093760 14.4 MiB
rss 32.9 MiB 15093760 14.4 MiB
rss 32.9 MiB 15093760 14.4 MiB

This clearly shows you how using variable and continuously incrementing the space required by it increases the heapTotal and correspondingly the Resident Set Size(rss)