Scaling Reddit from 1 Million to 1 Billion – Pitfalls and Lessons [video] (opens in new tab)

Bugmenot is great for sites like this.

In this and some other technical topics, people end up discussing their personal tastes with web site's design, their individual UI frustrations with some button on the web site, the font, the color, and other random non-relevant topic; like now the profitability.

When that blog post went up I was as surprised as you to see it wasn't profitable when I was there.

I can definitely see millions of networked memcache calls being a bottleneck, and if the batching adds another ms per req on average, but removes the bottleneck, then they can serve a lot more users at a cost of 1ms per req.

Is there anything in TFA that would support my theory? I don't know. I don't care enough to endure InfoQ. (I did for a Rich Hickey talk once, lo these various months, and yea it were a minor inconvenience).

Edit: whoa jedbergo!

http://imgur.com/Vr6BqDq

Those are some of the important lessons, although use (postgres|cassandra) are really too prescriptive. More like "use the right tool or tools for the job".

Also, use consistent key hashing where appropriate is another important less that I should emphasize more.

And "build for 3" is another important lesson. It makes scaling much easier.

I'll probably be back to check out more of the videos, but definitely not because of the site. If the editing is good, YouTube is just fine, otherwise SlideShare plus an audio file is just perfect.

Edit:

    [F] First Byte Time
    [C] Keep-alive Enabled
    [C] Compress Transfer
    [A] Compress Images
    [A] Progressive JPEGs
    [F] Cache static content
    [ ] Effective use of CDN

A full transcript with interleaved slide images takes a few minutes to read at most, and lets you control the pace of information absorption. A video with slides, especially when you cannot 2x the talking speed, is a painfully slow data transfer method.

Video + Slides = analog modem

Transcript w/ embedded slides = Google fiber :-)

Of course, if you're into audio books instead of reading, maybe you consider that a feature.

// I push video for a living. It's great for visual explanation like DIY instruction (e.g. woodworking, swapping RAM on a Mac Mini), emotional content, personal story telling, etc. Systems architecture is generally not in one of those categories.

I don't have a solid block of 40 undisturbed minutes to listen to a talk. Give me a transcript and I can read a paragraph here and there as I do other things at my own pace. I might have ten minutes here, ten minutes there. I don't want to be constantly pausing/unpausing the video, or worse - switching between the video and my music.

Plus, if I concentrate, I could read a 40 minute talk in 20 minutes or less.

Basically, when I'm reading, I control the pace. I rarely watch videos that are longer than about 5 minutes (that aren't entertainment, which is entirely different).

Memcache has no guarantees about durability, but is very fast, so the vote data is stored there to make rendering of pages as quick as possible.

Cassandra is durable and fast, and gives fast negative lookups because of its bloom filter, so it was good for storing a durable copy of the votes for when the data isn't in memcache.

Postgres is rock solid and relational, so it was a good place to store votes as a backup for Cassandra (we could regenerate all the data in Cassandra from Postgres if necessary) and also for doing batch processing, which sometimes needed the relational capabilities.

A lot of those people aren't interested in that content, so it will suddenly get an influx of downvotes.

It's important to keep in mind that reddit was already doing twice as much traffic as Digg before they launched v4.

Funny story about that. When we were owned by Conde, the accounting was a little different (they took on some of the charges, like Akamai), and so we were actually told we were slightly profitable.

When that blog post went up I was as surprised as you to see it wasn't profitable when I was there.

Firstly, as with Wikipedia, if Reddit were forced to close because of money issues, Reddit could simply post a 'donate now or reddit shuts down' post and they would likely be rolling in millions of dollars.

Second, simply because reddit itself is not profitable does not mean people are not making a lot of money off reddit. The moderator system lends itself very well to a kind of 'corporate capture' of communities where moderators can be (and are) bought off for very tidy sums.

Source?