One Billion Cells – Another Multiplayer Demo with Clojure

58 pointsposted 7 months ago
by adityaathalye
(cells.andersmurphy.com)

21 Comments

andersmurphy

7 months ago

Oh, fun. I wasn't expecting this on here so soon. It's very MVP and currently running on a 5$ VPS.

Happy to answer any questions.

andersmurphy

7 months ago

And we're back on a 10$ VPS.

konsalexee

7 months ago

What is the full stack you are using? What parts also require scaling up? DB, bandwidth orrr?

andersmurphy

7 months ago

So the stack is datastar + clojure + sqlite + caddy on a hetzner VPS 2 core 2G.

The scaling was preemptive as it was hitting 150% CPU (out of 200%). Needed to power down to rescale.

Now it's hovering at around 200% (out of 400%). About 80kb/s and 10 disk iops.

Everything goes via a sqlite db.

daymanstep

7 months ago

How are you doing the throttling? I imagine one malicious player might do like 10000 iops to your DB.

andersmurphy

7 months ago

So there's no rate limiting.

But because it's sqlite it's a single writer. Everything gets batched as one transaction every 100ms. The operations on a single chunk gets squashed into a single write.

Even without the squashing sqlite can handle 10000-20000+ updates/s because of the transaction batching.

With the chunk based squashing all edits to a chunk in that 100ms window become one update, so it can scale quite well.

matsemann

7 months ago

But the question wasn't really if you can handle it, but more if someone could control the whole board themselves, I think?

andersmurphy

7 months ago

Oh, I mean they could try. It's a very big board. Probably possible though if someone is sufficiently motivated.

matsemann

7 months ago

I see a snake eating the 0,0 part now at least, heh.

Btw, if I add a ' to the string, it's impossible to override by othrs. At least in the UI on Firefox, the snake still ate it.

ac50hz

7 months ago

Anders’ blog is a joy to read.

andersmurphy

7 months ago

Thank you for the kind words.

I'm planning on doing a write up on th se billion-foo style games at some point. It's been a fantastic learning experience.

ac50hz

7 months ago

I’m looking forward to it.

amadeuspagel

7 months ago

On mobile, when I click on one of the cells, my keyboard opens.

andersmurphy

7 months ago

So that you can type in the field. It does shift the layout which is annoying.

I put this together in a day and wasn't planning on it being on HN. So there's definitely some jank/UX polish.

For example the typing experience is nicer on chrome as the field sizes to the text.

freilanzer

7 months ago

What the hell am I even looking at?

Theofrastus

7 months ago

Has someone already animated Bad Apple on there?

Or played Doom, for that matter.

andersmurphy

7 months ago

I'm just heading off on holiday so if someone does... Please make a gif so I can watch it on my return.

There's a bad apple demo on the datastar site. Datastar's[1] streaming hypermedia is what makes this possible, that and good old Clojure and sqlite.

- [1] https://github.com/starfederation/datastar

aquariusDue

7 months ago

Datastar is amazing, I can't wait for the next big release.

Once everything clicks it becomes a force multiplier and a joy to work with, something that helped me in that regard is throwing a "data-json-signals" on an element so its easier to keep an eye on things.