/webrtc-many-datachannels

A reproduction of a Firefox bug whereby it can't create a lot of WebRTC datachannels

Primary LanguageJavaScript

WebRTC many datachannels

This repo contains three scripts:

  1. sig-server.js Starts a WebSocket server that is used for signalling between the sender and recpients
  2. recipient.js Opens a connection to sig-server and listens for incoming WebRTC connections
    • For any incoming datachannel that is opened, accept any data message and write it back into the channel
  3. sender.js Connects to recipient.js via sig-server, then in a loop, opens a datachannel on the connection, writes a small message into it, waits for it to be received and closes the channel

Running

  1. Install dependencies
$ npm i
  1. Start the sig-server
$ node sig-server.js
signaling server has started on: http://127.0.0.1:8080
  1. Start the recipient

Chrome:

$ npx pw-test ./recipient.js

Firefox:

$ npx pw-test --browser firefox ./recipient.js

Any browser:

https://codepen.io/achingbrain/pen/yLWpJrB

  1. Start the sender

Chrome:

$ npx pw-test ./sender.js

Firefox:

$ npx pw-test --browser firefox ./sender.js

Any browser

https://codepen.io/achingbrain/pen/dyEJXLz

Expected behaviour

Many messages should be logged, the channel id should increase:

// sender.js
...
Ping channel-5646 took 1ms
Ping channel-5647 took 1ms
Ping channel-5648 took 1ms
Ping channel-5649 took 0ms
Ping channel-5650 took 1ms
...

The recipient should log corresponding events for each channel:

// recipient.js
...
channel-5646 open
channel-5646 data
channel-5646 close
channel-5647 open
channel-5647 data
channel-5647 close
channel-5648 open
channel-5648 data
channel-5648 close
...

Observed behaviour

Sender Recipient Result
Chrome Chrome ✅
Chrome Firefox ✅
Firefox Chrome ❌
Firefox Firefox ❌

In both cases Firefox as a sender stops sending data after a very small number of iterations:

Ping channel-1 took 28ms
Ping channel-2 took 5ms
Did not receive ping response on channel-3 after 5005ms