[Bug] Manager leaks an EIO socket when disconnect is called right before connecting again

[benjamin-albert]

Steps to reproduce

server.js:

var io = require('socket.io')(1337);

io.of('/asd');
io.of('/foo');

client.js:

var io = require('./');
var manager = io.Manager('http://localhost:1337', { transports: ['websocket'] });

var fooSocket = manager.socket('/foo');
fooSocket.on('connect', function() {
  // This disconnect should not break
  // the conection of the asdSocket.
  fooSocket.disconnect();

  var asdSocket = manager.socket('/asd');

  // Only fail if reconnect_attempt it emitted
  // even if the IEO Socket was successfully opened.
  manager.engine.on('open', function() {
    asdSocket.on('reconnect_attempt', function() {
      console.error('Why reconnect? This is a bug!');
    });
  })

  asdSocket.on('connect', function() {
    asdSocket.disconnect();
    console.error('Node.js should exit after all clients have disconnected');
  });
});

Expected behavior

Node.js should exit after all clients have disconnected.

Actual behavior

Node.js freezes for about a second (before it tries to reconnect) and then it stays open forever (doesn't exit).

Workaround

I am aware that the proper way to do something like this is to first connect to the second namespace and then disconnect from the first namespace.

However I don't think something like this should leak an IEO socket.

Setup

• OS: macOS Version 10.12
• browser: Node.js v4.6.1
• socket.io version: 1.5.0

Other information

See this commit in my fix_eio_leak branch which adds a failing test to test/connection.js

Stay tuned for a pull request that fixes this bug.

[darrachequesne]

For future readers:

This should be fixed by 99c2cb8, included in socket.io-client@4.4.0.