Websocket NodeJS localhost connected over server (High Latency)

[mahir-zeroday]

Is there an existing issue for this?

• I've searched for any related issues and avoided creating a duplicate issue.

Description

Hello,
I have a question about whether this is a bug or an unusual situation.
I'm sending ping requests from NextJS (localhost:3000) to NodeJS (localhost:8080). I create the ping request myself and send the current time using Date.now() to port 8080 and get it back.
I subtract the timestamp in the message from Date.now() when I receive the message and divide by 2.
This creates a difference of around 13~18ms. I think this difference is quite high for websocket communication between two ports on localhost.
Can I get information about this situation? Are these numbers normal?

ws version

8.18.0

Node.js Version

22.0.0

System

System:
OS: macOS 15.1.1
CPU: (11) arm64 Apple M3 Pro
Memory: 99.66 MB / 18.00 GB
Shell: 3.2.57 - /bin/sh

Expected result

No response

Actual result

No response

Attachments

No response

[lpinca]

The numbers are unusual but it has nothing to do ws. I think it is more a network issue. Below is an example in my environment.

// server.mjs
import { WebSocketServer } from 'ws';

const websocketServer = new WebSocketServer({ port: 8080 }, function () {
  console.log('Server listening on port *:8080');
});

// client.mjs
import WebSocket from 'ws';

const ws = new WebSocket('ws://localhost:8080');

ws.on('open', function () {
  ws.ping(Date.now());
});

ws.on('pong', function (data) {
  const time = +data.toString();
  console.log(`Round-trip time: ${Date.now() - data} ms`);

  setTimeout(function () {
    ws.ping(Date.now());
  }, 500);
});

$ node client.mjs
Round-trip time: 2 ms
Round-trip time: 1 ms
Round-trip time: 1 ms
Round-trip time: 1 ms
Round-trip time: 1 ms
Round-trip time: 1 ms
Round-trip time: 1 ms
Round-trip time: 0 ms
Round-trip time: 1 ms
Round-trip time: 1 ms
Round-trip time: 1 ms
Round-trip time: 1 ms
Round-trip time: 1 ms
Round-trip time: 1 ms
Round-trip time: 1 ms
Round-trip time: 0 ms
Round-trip time: 1 ms
...

[mahiraltinkaya]

Thank you @lpinca ;
I examined your example code and applied it for testing. I'm getting similar results. I think I'm running into some browser or Next.js related factors here. Thank you for your interest.

[lpinca]

I'm closing this as answered.