node.js v16 array iterator blocking test

curl.fish

#!/usr/bin/env fish

# Once node server is running, run test by endpoint name:
# ./curl.fish long1

function getTime
	printf (cat $argv | awk '{ print $1 }')
end

while true
	echo :: long call start
	command time -ho longTime curl -s localhost:3000/$argv > /dev/null & 
	set longPid $last_pid
	sleep 0.05

	echo :: hello call start
	command time -ho shortTime curl -s localhost:3000/hello > /dev/null
	echo :: hello call finished in (getTime shortTime) + 0.05s

	wait $longPid
	echo :: long call finished in (getTime longTime)

	echo
	sleep 1
end

index.js

// node v16.17.0 amd64 under macOS Rosetta

const express = require('express')
const app = express()
const port = 3000

app.get('/hello', (req, res) => {
  res.send('Hello World!')
})

const n = 100000000
const arr = Array(n).fill(Math.random())

// blocks -> blocks event loop

// ~0.12s, blocks
app.get('/long1', (req, res) => {
  let sum = 0
  for (let i = 0; i < arr.length; i++) {
    sum += arr[i]
  }
  res.send(sum.toString())
})

// ~0.47s, blocks
app.get('/long2', (req, res) => {
  let sum = 0
  for (const el of arr) {
    sum += el
  }
  res.send(sum.toString())
})

// ~1.89s, blocks
app.get('/long3', (req, res) => {
  let sum = 0
  arr.forEach(el => {
    sum += el
  })
  res.send(sum.toString())
})

// ~0.9s, blocks
app.get('/long4', (req, res) => {
  const sum = arr.reduce((prev, el) => {
    prev += el
  })
  res.send(sum.toString())
})

app.listen(port, () => {
  console.log(`Example app listening on port ${port}`)
})

output-sample.txt

taylor@Taylors-MacBook-Pro ~/p/t/exp-test> ./curl.fish long4
:: long call start
:: hello call start
:: hello call finished in 0.87s + 0.05s
:: long call finished in 0.91s

:: long call start
:: hello call start
:: hello call finished in 0.88s + 0.05s
:: long call finished in 0.93s

:: long call start
:: hello call start
:: hello call finished in 0.85s + 0.05s
:: long call finished in 0.90s

:: long call start
:: hello call start
:: hello call finished in 0.86s + 0.05s
:: long call finished in 0.92s