Ask HN: How many users per server? | Hacker News Reader

Ask HN: How many users per server?

4 pointsalmosnow3 comments

I understand that there are a lot of variables involved, like:

- The service you provide and what your users do - Your hardware

But still it would be interesting to discuss your personal experience with this.

For example, I'm currently developing a kind-of online CMS service. Atm I'm able to support around 250-300 concurrent users using a modest dual-core server (which performs similar to an Amazon EC2 'core'), horizontal scale is almost linear. My current goal is to achieve a rate of 1000 concurrent users on a cheap EC2 instance.

As another example, 'somewhere' I've read that Facebook receives around 100 million of concurrent users. 'Somewhere else' I-ve read that thay are using around 200,000 servers. So you could think that the efficiency they've achieved is around 500 users per server.

Obviously this depends a lot on your stack: Node.js is going to be your best bet though. Sinatra + Unicorn can drive some pretty nice reqs/second, but if what you need is actual "concurrency" as opposed to just reqs/second performance, go Node. Express benchmarks that I ran a few months ago were showing ~7k requests per second, and I've heard claims of well over 10k.

Depending on your scale, your DB could be another potential bottleneck. Heroku provides hosted PostgreSQL DB's as a standalone service, and their performance has served me well in the past; could be worth looking into for you. Also, of course there's the Mongo in the room: I've heard mixed reviews, and I've never employed it in production myself so I have no wisdom to impart regarding it. Just be aware of your options :)

What is the bottleneck you're hitting at 300 concurrent users? Is everything hosted on a single box? You might see better performance if you had a separate database and app server if CPU or disk I/O is the bottleneck.

1000 concurrent users? Are you prematurely optimizing? Very very very few sites get that many concurrent users. I own a site that gets 1500 visitors a day, and usually there's 12-15 concurrent users.

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