Technology

@sunaurus there's a lot of upvoting happening on popular subreddits

Yeah, apparently I was wrong about this (still learning lemmy and fediverse stuff...). Text content of posts and comments are "synced" to your server and stored in your database there. Then future requests for that content are served from your instance. So its not as bad as I thought it was (the network load should be lower since you aren't acting as entirely a proxy, more like a cache), but database bloat will be a huge problem (its already a big problem in other federated things like mastodon and matrix, where every server ends up saving everything they want into their own database).

I'm not sure what happens when the original server goes down, does the federated servers discard that data? Or do we each maintain a forever copy until we want to get rid of it ourselves? There's also some notes I've seen about how servers only incrementally cache federated content (only posts and comments that are viewed by someone are fetched, and new comments may not be fetched until someone wants to see it)... so not everybody has a "pure and full" copy of posts necessarily.

But overall I wonder how all the various sysadmins hosting these lemmy instances will deal with the expotential growth they're going to see, or if smaller instances will start defederating to save on hardware costs (no reason for my tiny instance that only talks about blue shiny rocks to federate with lemmy.world and store all that content)

Information about post changes on the originating instance come in pretty much in real time, and get saved in the local database.

If the local instance is configured with pictrs support images are also cached locally.

No. The "single source of truth" is the instance hosting the community. If it goes down the community itself goes down with the ship. The only way to prevent it is to have a IT infrastructure that can provide redundancy

If it's just a temporary outage, whatever the mirror has received prior to the outage will be shown to users on that other instance but only local interactions for that instance will update it, when it comes back up, things like votes and comments will be synchronized again across all of the instances.

For permanent outages, the community will just need to be started again on a new instance.

Funny how you say it's not a problem, then go on to describe the problem that needs to be dealt with. Dealing with scaling is a problem, and it's a problem that costs money.

Posts like this: https://lemm.ee/post/58472 suggest it is a problem. The rise in traffic seen by Lemmy in the last few days is absolutely tiny compared to a site like reddit, and already instances are struggling to cope. The recent growth in user registrations represents only about 0.007% of reddit's active user base. (~60K new Lemmy users vs 861,000,000 active monthly reddit users). A site like reddit costs millions to run.

There are 190+ Lemmy instances last time I checked, yet almost all the brunt of this load has been borne by a handful of servers, which see an inordinate amount of traffic while 100+ other servers sit around idle. Why should a handful of "lucky" servers have to pay all the hosting costs? What if a volunteer-run instance explodes to reddit-like levels of popularity? It will simply fold, unless the volunteer has serious money to throw at the problem.