if I selfhost, does that take any load of Lemmy?
if I selfhost, does that take any load of Lemmy?
Like does content get mirrored to my instance and then mine distributes it ala BitTorrent or is my instance it's own thing?
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Broadly, yes. The way federation works means anything any user on your instance is interested in will be sent to you once (at least posts/comments/votes/etc). Whenever someone on your instance views that thing that is a request that would otherwise be made to another instance. This does, however, increase the load of federation on servers hosting popular communities, as now they have to send each post/comment/vote/whatever to your instance. Unlike bit torrent there is only one place responsible for sending you all of the content that exists in a community, so the fediverse doesn't get p2p-style network effects where every peer/sever helps even a bit.
A single user instance is a little inefficient, unless you are actually looking at most/all of the content your instance receives, in which case it is probably a wash. The ideal for how federation is implemented in ActivityPub would be many similarly-sized (in terms of user count) instances with the most popular communities being spread out among them.
Sadly right now the most popular instances (lemmy.world, lemmy.ml, lemmynsfw.com, kbin.social) are both where users and communities are, so the real gains to help those instances (several of which continue to struggle under the load) are really only medium and larger sized instances.
What is the easiest way to learn about ActivityPub?
These posts are really useful to get a grasp of ActivityPub (if you have a programming background): https://rknight.me/building-an-activitypub-server/ https://blog.joinmastodon.org/2018/06/how-to-implement-a-basic-activitypub-server/
And of course the official spec (although its less useful): https://www.w3.org/TR/activitypub/
Isn't a semi-significant amount of the per instance load in the database interactions though? I don't know if that's still true after some of the optimizations in 0.18, but by having your own instance, even 1 person instance, you no longer load the database of another instance with calculating hot/active/whatever for things you want to see, and you don't load it when you do pulls.
There is certainly an inflection point. I am not sure where it falls. If you rarely use Lemmy the other servers are expending effort federating to you for no reason, so for a heavy single user it is probably a positive. I imagine it also varies based on how you browse as "new" is probably "lighter" than "hot" or "active".
Sure, but the server calculates the hot/active every 15 minutes regardless of whether or not you browse it. It's calculated on a timed job so it's always fresh and ready for everyone.
I was unaware that was the case, that's pretty expensive and inefficient to do it for every user (because each user's "Subscribed" feed is likely different) every 15 minutes regardless of how recently they've visited. The inflection point is probably lower for the benefits of even single-user instances in that case.