[Vishnevskiy]

These machines do more than just push. They also buffer messages for each individual user to "potentially" push if they don't read them on the desktop client. This happens before the flow this article talks about.

We currently have 3 machines doing this for millions of concurrent users. At the writing of this article it was 2 machines.

[jsjohnst]

What size machines are these? I'm shocked that this volume is your max handling with Erlang unless your using a smaller T series AWS instance for this.

[Vishnevskiy]

These are n1-standard8 on GCE.

These are getting easily over 30,000 requests a second each about updating queues for new messages. And also are subscribed to presence events from our presence system to millions of people. It is a very busy service ensuring we only deliver messages to people not at their computer.

[jsjohnst]

So if they are delivering 30k a second per box and the max "backlog" you allow to build is ~50k, then you cap your backlog at under 2sec worth of delivery? Or am I missing something?