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benchmark: add test for module loader

Adds a test for benchmarking the module loader, needed for benchmarking
changes / refacortings in the module loader.

Reviewed-by: Trevor Norris <>
Reviewed-by: Timothy J Fontaine <>
latest commit efa47e593d
@robertkowalski robertkowalski authored trevnorris committed
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arrays bench: Consistency in benchmark filenames
buffers bench: fix buffers/buffer-base64-encode benchmark
crypto benchmark: hash stream
fs benchmark: Correct the bufferSize to highWaterMark
http benchmark: update to use new wrk
misc benchmark: add test for module loader
net stream_wrap: use `uv_try_write` where possible
tls benchmark: fixate `ciphers` in tls benchmarks doc: Add a README for benchmark tests
common.js benchmark: Fix execArgv handling
compare.js bench: compare binaries equal times
fs-write-stream-throughput.js fs: Change default WriteStream config, increase perf benchmark: Make flamegraphs a bit more useful benchmark: Set port range properly on Linux
http_bench.js bench: add continuous stress test
http_server_lag.js Typo in http_server_lag.js script
http_simple.js bench: Make http easier to profile
http_simple.rb fix whitespace errors
http_simple_auto.js bench: use res.end() for chunked encoding bench: fetch port from env
http_simple_cluster.js bench: start a worker for each CPU
idle_clients.js Add extra anti-DoS tech to net.Server
idle_server.js Abstract out a Server.prototype.pause method
io.c bench: Make io.c output easier to read
plot.R Bump size of bench histogram to 100ms
report-startup-memory.js Add startup memory script to benchmarks
static_http_server.js benchmark: Add resume() in static_http_server

Node.js core benchmark tests

This folder contains benchmark tests to measure the performance for certain Node.js APIs.

How to run tests

There are two ways to run benchmark tests:

  1. Run all tests of a given type, for example, buffers
node benchmark/common.js buffers

The above command will find all scripts under buffers directory and require each of them as a module. When a test script is required, it creates an instance of Benchmark (a class defined in common.js). In the next tick, the Benchmark constructor iterates through the configuration object property values and run the test function with each of the combined arguments in spawned processes. For example, buffers/buffer-read.js has the following configuration:

var bench = common.createBenchmark(main, {
    noAssert: [false, true],
    buffer: ['fast', 'slow'],
    type: ['UInt8', 'UInt16LE', 'UInt16BE',
        'UInt32LE', 'UInt32BE',
        'Int8', 'Int16LE', 'Int16BE',
        'Int32LE', 'Int32BE',
        'FloatLE', 'FloatBE',
        'DoubleLE', 'DoubleBE'],
        millions: [1]

The runner takes one item from each of the property array value to build a list of arguments to run the main function. The main function will receive the conf object as follows:

  • first run:
    {   noAssert: false,
        buffer: 'fast',
        type: 'UInt8',
        millions: 1
  • second run:
        noAssert: false,
        buffer: 'fast',
        type: 'UInt16LE',
        millions: 1


In this case, the main function will run 2214*1 = 56 times. The console output looks like the following:

buffers/buffer-read.js noAssert=false buffer=fast type=UInt8 millions=1: 271.83
buffers/buffer-read.js noAssert=false buffer=fast type=UInt16LE millions=1: 239.43
buffers/buffer-read.js noAssert=false buffer=fast type=UInt16BE millions=1: 244.57
  1. Run an individual test, for example, buffer-slice.js
node benchmark/buffers/buffer-read.js

The output:

buffers/buffer-read.js noAssert=false buffer=fast type=UInt8 millions=1: 246.79
buffers/buffer-read.js noAssert=false buffer=fast type=UInt16LE millions=1: 240.11
buffers/buffer-read.js noAssert=false buffer=fast type=UInt16BE millions=1: 245.91

How to write a benchmark test

The benchmark tests are grouped by types. Each type corresponds to a subdirectory, such as arrays, buffers, or fs.

Let's add a benchmark test for Buffer.slice function. We first create a file buffers/buffer-slice.js.

The code snippet

var common = require('../common.js'); // Load the test runner

var SlowBuffer = require('buffer').SlowBuffer;

// Create a benchmark test for function `main` and the configuration variants
var bench = common.createBenchmark(main, {
  type: ['fast', 'slow'], // Two types of buffer
  n: [512] // Number of times (each unit is 1024) to call the slice API

function main(conf) {
  // Read the parameters from the configuration
  var n = +conf.n;
  var b = conf.type === 'fast' ? buf : slowBuf;
  bench.start(); // Start benchmarking
  for (var i = 0; i < n * 1024; i++) {
    // Add your test here
    b.slice(10, 256);
  bench.end(n); // End benchmarking
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