Distributed chat/alert system, what to write on?

Question

PHP

Hello.
I need a notification system for the site, as an android developer, the first thing that comes to my mind is gcm, but it is only for google chrom, the second thought is long polling, but I'm afraid the server will fall under heavy loads.
In fact, long polling suits me, what technology would you recommend to simply add a server if necessary?
A large number of connections are expected, but not too active - normal behavior is a couple of alerts per minute and then an hour of downtime
Messages should be delivered "now or never"
Sorry for the somewhat rambling description, thanks in advance.

Answer 1

Go+websockets

Answer 2

socket.io

Answer 3

ERLANG :)

Answer 4

https://fzambia.gitbooks.io/centrifugal/content/

Answer 5

Go + websockets , as Alexander Pavlyuk answered. I'm doing it right now