recursive fs.readdir benchmark

readdirbench.js

"use strict";

const fs = require("fs");
const util = require("util");
const p = process.argv[2];

function time() {
  const t = process.hrtime();
  return Math.round((t[0] * 1e9 + t[1]) / 1e6);
}

const walk = function(dir, cb) {
  let files = [], dirs = [];
  fs.readdir(dir, (_, entries) => {
    (function next(i) {
      if (!entries || !entries[i]) return cb(null, [dirs, files]);
      const path = dir + "/" + entries[i];
      fs.stat(path, (_, stat) => {
        if (stat && stat.isDirectory()) {
          dirs.push(path);
          walk(path, (d, f) => {
            dirs = dirs.concat(d);
            files = files.concat(f);
            next(++i);
          });
        } else {
          files.push(path);
          next(++i);
        }
      });
    })(0);
  });
};

const walkSync = function(dir) {
  let files = [], dirs = [];
  const entries = fs.readdirSync(dir);
  for (let i = 0, l = entries.length; i < l; i++) {
    const path = dir + "/" + entries[i];
    const stat = fs.statSync(path);
    if (stat.isDirectory()) {
      dirs.push(path);
      const r = walkSync(path);
      dirs = dirs.concat(r[1]);
      files = files.concat(r[2]);
    } else {
      files.push(path);
    }
  }
  return [dirs, files];
};

const walkNew = function(dir, cb) {
  let files = [], dirs = [];
  fs.readdir(dir, {withFileTypes: true}, (_, entries) => {
    (function next(i) {
      if (!entries || !entries[i]) return cb(null, [dirs, files]);
      const path = dir + "/" + entries[i].name;
      if (entries[i].isDirectory()) {
        dirs.push(path);
        walkNew(path, (d, f) => {
          dirs = dirs.concat(d);
          files = files.concat(f);
          next(++i);
        });
      } else {
        files.push(path);
        next(++i);
      }
    })(0);
  });
};

const walkNewSync = function(dir) {
  let files = [], dirs = [];
  const entries = fs.readdirSync(dir, {withFileTypes: true});
  for (let i = 0, l = entries.length; i < l; i++) {
    const path = dir + "/" + entries[i].name;
    if (entries[i].isDirectory()) {
      dirs.push(path);
      const r = walkNewSync(path);
      dirs = dirs.concat(r[1]);
      files = files.concat(r[2]);
    } else {
      files.push(path);
    }
  }
  return [dirs, files];
};

function sleep(ms) {
  return new Promise(resolve => setTimeout(resolve, ms));
}

async function run(fn, name) {
  await util.promisify(fs.writeFile)("/proc/sys/vm/drop_caches", "3", () => {});
  await sleep(5000);
  const start = time();
  await fn(p);
  console.log(name, time() - start, "ms");
}

(async () => {
  await run(walkSync, "readdir sync");
  await run(util.promisify(walk), "readdir async");
  await run(walkNewSync, "readdir withFileTypes sync");
  await run(util.promisify(walkNew), "readdir withFileTypes async");
})();