性能测试

看到一篇英文博客《How to read files quickly in JavaScript》对 JS 常用的 5 中文件读取方法做一个性能测试：

测试方案：同一个文件（大约 1KB），读 50000 次，看耗时情况。
测试环境：一台几十个 Intel 核心和充足内存的服务器。
语言环境：Node 20.1 和 Bun 1.0.14

• test1.js (fs/promises)

  const fs = require("fs/promises");
  const readFile = fs.readFile;
  let start = Date.now();
  let count = 0;
  const N = 50000;
  for (let i = 0; i < N; i++) {
      readFile("lipsum.txt", { encoding: "utf-8" })
          .then((data) => {
              if (data.length != 1335) throw 1;
              count++;
              if (count == N) {
                  end = Date.now();
                  console.log("time: ", end - start);
              }
          })
          .catch((err) => {
              throw 1;
          });
  }
  

• test2.js (fs.readFile + util.promisify)

  const fs = require("fs");
  const util = require("util");
  const readFile = util.promisify(fs.readFile);
  let start = Date.now();
  let count = 0;
  const N = 50000;
  for (let i = 0; i < N; i++) {
      readFile("lipsum.txt", { encoding: "utf-8" })
          .then((data) => {
              if (data.length != 1335) throw 1;
              count++;
              if (count == N) {
                  end = Date.now();
                  console.log("time: ", end - start);
              }
          })
          .catch((err) => {
              throw 1;
          });
  }
  

• test3.js (fs.readFileSync)

  const fs = require("fs");
  const readFileSync = fs.readFileSync;
  let start = Date.now();
  let count = 0;
  const N = 50000;
  for (let i = 0; i < N; i++) {
      var data = readFileSync("lipsum.txt", { encoding: "utf-8" });
      if (data.length != 1335) throw 1;
  }
  console.log("time: ", Date.now() - start);
  

• test4.js (fs.readFileSync + promise)

  const fs = require("fs");
  const readFileSync = fs.readFileSync;
  async function f(name, options) {
      return readFileSync(name, options);
  }
  let start = Date.now();
  let count = 0;
  const N = 50000;
  for (let i = 0; i < N; i++) {
      f("lipsum.txt", { encoding: "utf-8" })
          .then((data) => {
              if (data.length != 1335) throw 1;
              count++;
              if (count == N) {
                  end = Date.now();
                  console.log("time: ", end - start);
              }
          })
          .catch((err) => {
              throw 1;
          });
  }
  

• test5.js (fs.readFile)

  const fs = require("fs");
  const readFile = fs.readFile;
  let start = Date.now();
  let count = 0;
  const N = 50000;
  for (let i = 0; i < N; i++) {
      fs.readFile("lipsum.txt", function read(err, data) {
          if (err) {
              throw 1;
          }
          if (data.length != 1335) throw 1;
          count++;
          if (count == N) {
              end = Date.now();
              console.log("time: ", end - start);
              start = end;
          }
      });
  }
  

• 测试脚本

  for i in {1..10}; do
  echo "trial ${i}"
  echo "node"
  node --version
  node test1.js > /dev/null
  node test1.js
  node test2.js > /dev/null
  node test2.js
  node test3.js > /dev/null
  node test3.js
  node test4.js > /dev/null
  node test4.js
  node test5.js > /dev/null
  node test5.js
  echo "Bun"
  bun run test1.js > /dev/null
  bun run test1.js
  bun run test2.js > /dev/null
  bun run test2.js
  bun run test3.js > /dev/null
  bun run test3.js
  bun run test4.js > /dev/null
  bun run test4.js
  bun run test5.js > /dev/null
  bun run test5.js
  done
  

PS：以上代码在 GitHub 上可以找到。

测试结果

说明：

1. Node 的 promise 不行（Bun 好得多）
2. 文件增大到 32KB 测试，Node 会报 heap limit Allocation failed（堆限制分配失败）
   Bun 没有问题，但是结论还是不受影响。