Volatile not behaving as expected

[shaiperfecto]

You want to:

• [x] report a bug

Current behaviour

Server sends (volatile!) messages in a rate of 300KB/s. Client's bandwidth is 150KB/s. Client receives (almost all) messages in order, with an increasing delay as time goes by.

Server drops messages when transport is not writable, but it only happens once/twice every 10/20 messages. According to this setup it should drop every other message.

Steps to reproduce (if the current behaviour is a bug)

Server Clone the following test project

https://github.com/shaiperfecto/socket.io-volatile-bug

npm install; npm start

Server starts at port 8081

Client Browse to http://:8081

Make sure you limit your network connection (either using Chrome devtools, I used Network link conditioner to 150KB/s

Expected behaviour

Server should drop messages when the client is still receiving the previously sent message

Setup

• OS: MacOS High Sierra
• browser: Chrome
• socket.io version: Latest

Other information (e.g. stacktraces, related issues, suggestions how to fix)

[illarion]

And this could be easily fixed if socket.io would support behavior described in #3158

[darrachequesne]

For future readers: I think this is fixed in latest versions, I wasn't able to reproduce down to version 2.1.1:

Without throttling:

2
3
4
5
...

With Chrome throttling at 150 kb/s:

3
34
64
94
125
...

Possibly related:

• https://github.com/socketio/engine.io/commit/01c6a12de51aa0252a6d624a7a968eb144655c3f
• https://github.com/socketio/engine.io/commit/ad5306aeaedf06ac7a49f791e1b76e55c35a564e

Please reopen if needed.