Deno vs Node.js: Performance comparison for file server

Published in

Tech Tonic

3 min readAug 28, 2022

From v1.25, Deno has introduced a totally new HTTP server called flash. The flash server is still under the unstable umbrella. The flash server is limited to HTTP/1.1 only. There is no HTTP/2 support yet. In this comparison, we’ll find out how the Deno’s new HTTP server stands in front of Node’s HTTP server when serving files.

Test setup

Environment

The performance comparison is executed on the following environment:

System: MacBook M1 with 16G of memory
Local: The SUT and tester are on the same system
Deno version: 1.25.0
Node version: 18.8.0

Code

The following is the code for the file server in both the runtimes. In both cases, only native APIs are used.

Node.js

const http = require("http");
const { stat } = require("fs").promises;
const fs = require("fs");const baseServePath = "./testdata";
const server = http.createServer(
  async (req, res) => {
    const filePath = baseServePath + req.url;
    const fileSize = (await stat(filePath)).size;
    res.writeHead(200, {
      "content-type": "application/pdf",
      "content-length": fileSize,
    });
    fs.createReadStream(
      filePath,
    ).pipe(res);
  },
);server.listen(3000);

In Node.js, we need to run a stat call to set the ‘content-length’ header.

Deno

const baseServePath = "./testdata";Deno.serve(async (req) => {
  const filePath = baseServePath + (new URL(req.url)).pathname;
  const file = await Deno.open(filePath);
  return new Response(file.readable, {
    headers: {
      "content-type": "application/pdf",
    },
  });
}, { port: 3000 });

In Deno, the content-length header is set by the new server. Therefore, no stat call is required.