BACKSTORY:
I was considering creation of client-server app to learn some new language and wanted it to have the best possible performance.

The client part is not an issue, it can be whatever, really... the server choice is pain in the ass...
I have looked up web server framework benchmark here: https://techempower.com/benchmarks/

So comparing those I have 2 options:
- Actix (Rust)
- Vert.x (Java)

I was about to use Vert.x, it handles requests asynchronously which seems nice.
However I thought, what if I wanted to sell this shit someday and Java requires licenses, while Rust don't.

I am terrible if it comes to licenses, so...

QUESTION:
How does Java licensing work?
It is on client to pay it cause he is using it or on me as a product owner?

Or should I switch to Rust already?

The way I understood it was that anybody running a Java based application for commercial use (clients in your case) must have a paid license to do so on a per-instance basis, whereas development requires a license on a per-developer or per-machine basis. Those two might need different licenses which would make sense, but I'm not sure since I don't use Java.
If my guesses are correct (correct me who can), then why not use OpenJDK for development, and not worry about what clients use?

Or Node.js, if you're okay with JavaScript/TypeScript

Or C# and .netcore

inb4 "or PHP"

General: I wanted something that will handle hundreds of users at the time without huge hiccups. Worked with something like that for few years and it was a pain in the ass if it comes to performance for 200 users, and I am not talking about HW now. Wanted to know if I can make something better myself 😅

@xprnio ok, that is somehow close to what I thought it is like. To OpenJDK part, it is ok to me, but I am aware that client might not be super happy if he had to pay me for app and Oracle for java. You know... just clients mentality...
Aand... I am totally not ok with JS xD had some bad time once... a month of pain. However it is on my list of languages I want to learn better. Someday.

@gintko as said, my decision was based on that benchmark. Didn't work with Java before, so wanted to learn. I was hoping their results are valid and can be trusted. I'll consider your options too, thanks.

@gruff I will look into it, thanks.

@xprnio definitely the way to go 🐵