Benchmark the time spent on transferring data in child process

_readme.md

Copy the file s and run node main.js. There's some numbers you can tweak at the top of the file imitating a project with some modules and average module file size.

It may take a while to run. Line 29 shows the time a took between a stdin write and stdout read for each request made.

child.js

process.stdin.on('data', (data) => {
  process.stdout.write(data.toString().repeat(1))
})

main.js

const { spawn } = require('child_process')
const { performance } = require('perf_hooks')

const NUMBER_OF_MODULES = 40000
const AVERAGE_MODULE_SIZE = 300 // characters

const child = spawn('node', ['child.js'])

const startTimes = {}
let idCounter = 0
let buffer = ''

child.stdout.on('data', (data) => {
  buffer += data.toString()
  let lines = buffer.split('\n')
  buffer = lines.pop() // Keep the last partial line in the buffer
  lines.forEach((line) => {
    if (line) {
      handle(line)
    }
  })
})

let durations = []

function handle(data) {
  const [id, message] = data.split(':')
  const endTime = performance.now()
  console.log(id, endTime - startTimes[id])
  durations.push(endTime - startTimes[id])
  delete startTimes[id]
  if (+id === NUMBER_OF_MODULES - 1) {
    console.log('avg', durations.reduce((a, b) => a + b, 0) / durations.length)
    process.exit()
  }
}

const inputs = Array.from({ length: NUMBER_OF_MODULES }, (_, i) => i + 1)
inputs.forEach((input) => {
  const id = idCounter++
  startTimes[id] = performance.now()
  child.stdin.write(`${id}:${'a'.repeat(AVERAGE_MODULE_SIZE)}\n`)
})