In order to reproduce the issue, please run the following:

$ npm install
$ node server.js

Then, in another terminal, or after you put the server in the background, run the client:

$ node client.js -c 1

This will make the client try to establish only one connection with the server using socket.io on top of TLS, then wait for a message to be sent by the server, and finally close the connection.

The issue is that most of the time, the client will be left hanging for a while because the connection is not closed properly.

To be able to reproduce the issue easily, instead of re-running the client until the connection hangs, you can also invoke it in a loop like following:

$ for i in `seq 1 30`; do node client.js -c 1; done