Chubby cuddlebot Lemma!

No no, the slashdot effect was the Popular Site posted a link to something cool someone had hosted on some little server because it was never supposed to be a big deal and thousands of humans saw the link and clicked on it. It wasn't slashdot itself consisting of thousands of servers that all automatically hit the linked site all at the same time without any humans following the link!

(speculation) normal usage might not have the same load, so catching might not be needed/wanted. But for the mastodon thing, there's a lot more requests made so higher load and need for the cache layer. Also, because it's just opengraph embed things, it's not Critical Information compared to actually reading a post

Cohost is rendered dynamically so it can have features like edits to posts and comments propagating in real time on already-loaded pages. This is a silly feature in some ways, but it’s been here since day 1, it’s part of the design bible I suppose, and if they can ever smash the “cohost going down blanks loaded cohost pages” bug with a hammer, I don’t see the harm. Staff has stated before that image hosting takes a much larger toll on resources than stuff like this. (Excepting the current bug of course.)

So the cache is only served to Mastodon servers (and maybe eventually other robot scrapers) and not anything else. This does mean that link previews are unfortunately not going to see dynamic updates but I suppose people don’t expect that.

we have explored more aggressive caching. here's a big list of things that wouldn't work:

• anything that depends on login state

this is almost everything on the site, including posts! things like "do we show embeds" and "do links open in an external tab" are settings, which means we need to know the value of the setting, which means the output is dependent on login state. this doesn't even get into shit like "blocking" and "private accounts" which come with their own whole new fun can of worms.

we can get away with having a mastodon/scraper-only cache because every single mastodon instance is always logged out, so login state is irrelevant. we could maybe over-engineer some sort of fragment caching system but this is almost certainly not worth doing for a four person team with only two engineers, especially on a site that is nearly 100% dynamic content.