js bench

bench.js

const map = new Map()

export const addToBench = (msg, cb) => {
  if (typeof msg === 'function') {
    msg = msg.name
  }
  const index = map.size
  map.set(msg, { 
    index,
    msg,
    cb,
    totalDuration: 0,
    totalRunLoop: 0,
    runCount: 0,
    opByMs: 0
  })
}

export const clearBench = () => map.clear()

const wait = delay => new Promise(r => setTimeout(r, delay))
const thousands = (x, sep = '_') => x.toString().replace(/\B(?=(\d{3})+(?!\d))/g, sep)

export const runBench = async () => {

  const NOOP = '(noop)' // "no operation" special case
  addToBench(NOOP, () => {})

  const runCount = map.size
  const runDuration = 100 // ms
  const runLoop = 1000

  await wait(100)

  const bundles = [...map.values()]

  for (const bundle of bundles) {
    bundle.totalDuration = 0
    bundle.totalRunLoop = 0
    bundle.runCount = 0
    bundle.opByMs = 0
  }

  for (let runIndex = 0; runIndex < runCount; runIndex++) {

    await wait(100)
    console.log(`bench run #${runIndex} (${bundles.map(b => b.index).join(',')})`)

    for (const bundle of bundles) {

      await wait(100)

      const { cb } = bundle
  
      const t = Date.now()
      let duration = 0
      while (true) {
        for (let i = 0; i < runLoop; i++) {
          cb(i, runLoop)
        }
        bundle.totalRunLoop += runLoop
        duration = Date.now() - t
        if (duration > runDuration) {
          break
        }
      }

      bundle.runCount++
      bundle.totalDuration += duration
    }

    // NOTE: important! 
    // order may have significant impact on performance
    // so between each run change the order
    bundles.unshift(bundles.pop())
  }

  for (const bundle of map.values()) {
    bundle.opByMs = bundle.totalRunLoop / bundle.totalDuration
  }

  // remove noop
  const noopBundle = map.get(NOOP)
  map.delete(NOOP)

  const faster = [...map.values()].sort((A, B) => B.opByMs - A.opByMs).shift()

  const lines = []
  lines.push(`bench (${runCount}/${runCount}):`)
  for (const bundle of [...map.values(), noopBundle]) {
    const { msg, opByMs } = bundle
    const isFaster = bundle === faster
    lines.push(`  ${msg}:`)
    lines.push(`    ${isFaster ? 'FASTER!' : `x${(faster.opByMs / opByMs).toFixed(3)}`}`)
    lines.push(`    op/ms: ${thousands(opByMs.toFixed(2))}`)
    lines.push(`    ${thousands(bundle.totalRunLoop)} in ${bundle.totalDuration}ms`)
    lines.push('')
  }
  console.log(lines.join('\n'))
}

test.js

import { addToBench, runBench } from './bench.js'

addToBench('un', () => [Math.random()])
addToBench('deux', () => [Math.random(), Math.random()])
addToBench('quatre', () => [Math.random(), Math.random(), Math.random(), Math.random()])
addToBench('huit', () => [Math.random(), Math.random(), Math.random(), Math.random(), Math.random(), Math.random(), Math.random(), Math.random()])

runBench()

output should be something like:

bench run #0 (0,1,2,3,4)
bench run #1 (4,0,1,2,3)
bench run #2 (3,4,0,1,2)
bench run #3 (2,3,4,0,1)
bench run #4 (1,2,3,4,0)
bench (5/5):
  un:
    FASTER!
    op/ms: 58_427.72
    29_506_000 in 505ms

  deux:
    x1.898
    op/ms: 30_778.22
    15_543_000 in 505ms

  quatre:
    x3.041
    op/ms: 19_211.88
    9_702_000 in 505ms

  huit:
    x5.502
    op/ms: 10_619.80
    5_363_000 in 505ms

  (noop):
    x0.501
    op/ms: 116_532.67
    58_849_000 in 505ms

beware that order may have significant impact :

with "huit" first:

addToBench('huit', () => [Math.random(), Math.random(), Math.random(), Math.random(), Math.random(), Math.random(), Math.random(), Math.random()])
addToBench('un', () => [Math.random()])
addToBench('deux', () => [Math.random(), Math.random()])
addToBench('quatre', () => [Math.random(), Math.random(), Math.random(), Math.random()])
runBench()

bench (5/5):
  huit:
    x4.056
    op/ms: 11_245.54
    5_679_000 in 505ms

  un:
    FASTER!
    op/ms: 45_611.88
    23_034_000 in 505ms

  deux:
    x1.451
    op/ms: 31_431.68
    15_873_000 in 505ms

  quatre:
    x2.411
    op/ms: 18_916.83
    9_553_000 in 505ms

  (noop):
    x0.391
    op/ms: 116_546.53
    58_856_000 in 505ms

"un" runs 23_034_000 times (29_506_000 when being first) -> x0.78 slower (-22%!!!)
"huit" runs 5_679_000 times (5_363_000 when being last) -> x1.05 faster (+5%)

side effects of JS optimization i guess