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I agree but also want to note that coordinating 1000 instances over ActivityPub brings it's own set of problems, rather than having one instance with 1000 users

I agree but also want to note that coordinating 1000 instances over ActivityPub brings it's own set of problems, rather than having one instance with 1000 users. Each new server introduced into the federation puts (minimal) additional load and traffic requirements on the other nodes, so more servers requires better servers. I do think that's the way forward though, rather than a few big instances, but time will tell what the right percentage of the split is for good performance for everyone.

kazinator 4y ago
I strongly suspect that connecting a new server to the federation, which has 1000 active users, is better than connecting 1000 more active users to an existing server. 1000 new users on an existing server are 1000 app/browser instances making separate network connections and separate little queries to that server. Whereas (I would hope) there are aggregation efficiencies in connecting a new 1000-user instance to the network. Also remember there are certain optimizations in Mastodon. If an instance A generates a toot, but the toot has no followers on instance B, then B doesn't see it. However, an instance always processes a toot from its own directly connected user's browser or Mastodon application.
michaelanckaert 4y ago
Yes, you're right on that point. I have read the ActivitPub spec but not the Mastodon API - so I'm probably wrong on the following part. Let's assume that we have 1000 users on a single server, posting a single message to those 1000 followers is writing a 1000 DB records (assuming a table with post - user link). Let's assume we have one server with 500 users, and 5 other servers with 100 users each. We still write 500 DB records on the first server, and make 5 API calls to the other servers, which each write 100 DB records. If the above holds true, the overhead is 5 extra API calls? At least, I hope Mastodon doesn't make API calls for every user on a server!
avdempsey 4y ago
Does ActivityPub support hierarchical federation? Or could it be grafted on?
- chipotle_coyote 4y ago
  I've been wondering about that. I joked not too long ago that Mastodon is the new FidoNet, but it does occur to me that there are probably things Mastodon could learn from FidoNet (or Usenet) if it hasn't learned them already.

kazinator 4y ago

I strongly suspect that connecting a new server to the federation, which has 1000 active users, is better than connecting 1000 more active users to an existing server. 1000 new users on an existing server are 1000 app/browser instances making separate network connections and separate little queries to that server. Whereas (I would hope) there are aggregation efficiencies in connecting a new 1000-user instance to the network. Also remember there are certain optimizations in Mastodon. If an instance A generates a toot, but the toot has no followers on instance B, then B doesn't see it. However, an instance always processes a toot from its own directly connected user's browser or Mastodon application.

michaelanckaert 4y ago

Yes, you're right on that point. I have read the ActivitPub spec but not the Mastodon API - so I'm probably wrong on the following part. Let's assume that we have 1000 users on a single server, posting a single message to those 1000 followers is writing a 1000 DB records (assuming a table with post - user link). Let's assume we have one server with 500 users, and 5 other servers with 100 users each. We still write 500 DB records on the first server, and make 5 API calls to the other servers, which each write 100 DB records. If the above holds true, the overhead is 5 extra API calls? At least, I hope Mastodon doesn't make API calls for every user on a server!

avdempsey 4y ago

Does ActivityPub support hierarchical federation? Or could it be grafted on?

chipotle_coyote 4y ago
I've been wondering about that. I joked not too long ago that Mastodon is the new FidoNet, but it does occur to me that there are probably things Mastodon could learn from FidoNet (or Usenet) if it hasn't learned them already.