Storing all genserver pid in ets table in each node

Again and again, you’re only saying what you are aiming to do and never once said why you are doing it.

Why were you using distributed Mnesia? What was wrong with a traditional database?

And what kind of app has 100s of millions of users? Are you working for Telegram?

You don’t seem to understand – we need to know what exact problem are you trying to solve. You already decided you’ll use 1000+ nodes and are asking how to do it. But we want to know why do you think you need those nodes.

Until you try to explain your needs and NOT repeat how you imagine your problem must be solved then nobody can help you.