Benchmark

Stability: 1.1 - Active Development

The node:benchmark module gives the ability to measure performance of JavaScript code. To access it:

import benchmark from 'node:benchmark';

const benchmark = require('node:benchmark');

This module is only available under the node: scheme. The following will not work:

import benchmark from 'benchmark';

const benchmark = require('benchmark');

The following example illustrates how benchmarks are written using the benchmark module.

import { Suite } from 'node:benchmark';

const suite = new Suite();

suite.add('Using delete to remove property from object', function() {
  const data = { x: 1, y: 2, z: 3 };
  delete data.y;

  data.x;
  data.y;
  data.z;
});

suite.run();

const { Suite } = require('node:benchmark');

const suite = new Suite();

suite.add('Using delete to remove property from object', function() {
  const data = { x: 1, y: 2, z: 3 };
  delete data.y;

  data.x;
  data.y;
  data.z;
});

suite.run();

$ node my-benchmark.js
(node:14165) ExperimentalWarning: The benchmark module is an experimental feature and might change at any time
(Use `node --trace-warnings ...` to show where the warning was created)
Using delete property x 5,853,505 ops/sec ± 0.01% (10 runs sampled)     min..max=(169ns ... 171ns) p75=170ns p99=171ns

Class: Suite

Stability: 1.1 Active Development

An Suite is responsible for managing and executing benchmark functions. It provides two methods: add() and run().

new Suite([options])

• options {Object} Configuration options for the suite. The following properties are supported:
  • reporter {Function} Callback function with results to be called after benchmark is concluded. The callback function should receive two arguments: suite - A {Suite} object and result - A object containing three properties: opsSec {string}, iterations {Number}, histogram {Histogram} instance.

If no reporter is provided, the results will printed to the console.

import { Suite } from 'node:benchmark';
const suite = new Suite();

const { Suite } = require('node:benchmark');
const suite = new Suite();

suite.add(name[, options], fn)

• name {string} The name of the benchmark, which is displayed when reporting benchmark results.
• options {Object} Configuration options for the benchmark. The following properties are supported:
  • minTime {number} The minimum time a benchmark can run. Default: 0.05 seconds.
  • maxTime {number} The maximum time a benchmark can run. Default: 0.5 seconds.
• fn {Function|AsyncFunction}
• Returns: {Suite}

This method stores the benchmark of a given function (fn). The fn parameter can be either an asynchronous (async function () {}) or a synchronous (function () {}) function.

$ node my-benchmark.js
(node:14165) ExperimentalWarning: The benchmark module is an experimental feature and might change at any time
(Use `node --trace-warnings ...` to show where the warning was created)
Using delete property x 5,853,505 ops/sec ± 0.01% (10 runs sampled)     min..max=(169ns ... 171ns) p75=170ns p99=171ns

suite.run()

• Returns: {Promise<Array<Object>>}
  • opsSec {number} The amount of operations per second
  • iterations {number} The amount executions of fn
  • histogram {Histogram} Histogram object used to record benchmark iterations

The purpose of the run method is to run all the benchmarks that have been added to the suite using the suite.add() function. By calling the run method, you can easily trigger the execution of all the stored benchmarks and obtain the corresponding results.

Using custom reporter

You can customize the data reporting by passing an function to the reporter argument while creating your Suite:

import { Suite } from 'node:benchmark';

function reporter(bench, result) {
  console.log(`Benchmark: ${bench.name} - ${result.opsSec} ops/sec`);
}

const suite = new Suite({ reporter });

suite.add('Using delete to remove property from object', () => {
  const data = { x: 1, y: 2, z: 3 };
  delete data.y;

  data.x;
  data.y;
  data.z;
});

suite.run();

const { Suite } = require('node:benchmark');

function reporter(bench, result) {
  console.log(`Benchmark: ${bench.name} - ${result.opsSec} ops/sec`);
}

const suite = new Suite({ reporter });

suite.add('Using delete to remove property from object', () => {
  const data = { x: 1, y: 2, z: 3 };
  delete data.y;

  data.x;
  data.y;
  data.z;
});

suite.run();

$ node my-benchmark.js
Benchmark: Using delete to remove property from object - 6032212 ops/sec

Setup and Teardown

The benchmark function has a special handling when you pass an argument, for example:

const { Suite } = require('node:benchmark');
const { readFileSync, writeFileSync, rmSync } = require('node:fs');

const suite = new Suite();

suite.add('readFileSync', (timer) => {
  const randomFile = Date.now();
  const filePath = `./${randomFile}.txt`;
  writeFileSync(filePath, Math.random().toString());

  timer.start();
  readFileSync(filePath, 'utf8');
  timer.end();

  rmSync(filePath);
}).run();

In this way, you can control when the timer will start and also when the timer will stop.

In the timer, we also give you a property count that will tell you how much iterations you should run your function to achieve the benchmark.minTime, see the following example:

import { Suite } from 'node:benchmark';
import { readFileSync, writeFileSync, rmSync } from 'node:fs';

const suite = new Suite();

suite.add('readFileSync', (timer) => {
  const randomFile = Date.now();
  const filePath = `./${randomFile}.txt`;
  writeFileSync(filePath, Math.random().toString());

  timer.start();
  for (let i = 0; i < timer.count; i++)
    readFileSync(filePath, 'utf8');
  // You must send to the `.end` function the amount of
  // times you executed the function, by default,
  // the end will be called with value 1.
  timer.end(timer.count);

  rmSync(filePath);
});

suite.run();

const { Suite } = require('node:benchmark');
const { readFileSync, writeFileSync, rmSync } = require('node:fs');

const suite = new Suite();

suite.add('readFileSync', (timer) => {
  const randomFile = Date.now();
  const filePath = `./${randomFile}.txt`;
  writeFileSync(filePath, Math.random().toString());

  timer.start();
  for (let i = 0; i < timer.count; i++)
    readFileSync(filePath, 'utf8');
  // You must send to the `.end` function the amount of
  // times you executed the function, by default,
  // the end will be called with value 1.
  timer.end(timer.count);

  rmSync(filePath);
});

suite.run();

Once your function has at least one argument, you must call .start and .end, if you didn't, it will throw the error ERR_BENCHMARK_MISSING_OPERATION.