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Comment by LeoPanthera | Hacker News Reader

I guess that explains why that page won't load, I guess the user is down.

OK, so this is an interesting thing. If I understand Paul (Bsky) correctly, one of the major reasons that they didn't adopt AP was that it could not scale well.

As in, if Mastodon got say 2 million new users in a few days, then each instance would have to sync the entire DB. Most instances could not handle that. In AT's case, that is handled more efficiently. That is correct, isn't isn't it?

Not really, no. A Mastodon server mostly only sees posts from users being followed by someone on their server, or mentioning someone on their server. Every post definitely does not get shipped to every server.

However, there's definitely some wild inefficiencies in federation: If thousands of servers do follow a given user, and that user posts a video file, all of those thousands of servers will download and store a copy.

The fediverse is largely analogous to email in that posts are addressed to destinations. Servers have inboxes and store what's sent to them.

Thank you for the reply. So aside from videos, let's say that millions of new users came to the fediverse, and 10's of thousands on each instance followed each other. Would that be handled well by most instances? Do they scale horizontally?

I am not a protocol partisan, just trying to understand what Paul meant in the interviews that I have seen.

It's going to depend a lot. Some of the big servers like mastodon.social likely can scale up very quickly, but some smaller niche-r servers might get hit harder. I doubt the activity of actually registering and following would cause a lot of problems, but I'd definitely expect media usage, moderation/spam management, etc. to pressure smaller servers. You definitely have a range of servers from Kubernetes-orchestrated platforms to "it runs on a box in my basement" hosts, but also the latter servers tend to be invite-only, and grow slower even during large waves of interest.

The biggest difference is that I'm not convinced Bluesky/Atproto has ever actually shown it can improve on these issues. Bear in mind, Bluesky isn't effectively federated at this point, everyone pretty much uses their services exclusively, so none of those inefficiencies exist... yet.

And... three days ago... Bluesky had an outage because it, a single service, couldn't handle the load: https://www.independent.co.uk/tech/bluesky-x-twitter-elon-mu...

While some ActivityPub servers might face issues with a big wave, it's very unlikely it would take down all of them. When mastodon.social suffered a big outage, I just went over and browsed from a different server, most of the rest of the fediverse just continued as normal.

Thank you, again.

> While some ActivityPub servers might face issues with a big wave, it's very unlikely it would take down all of them. When mastodon.social suffered a big outage, I just went over and browsed from a different server, most of the rest of the fediverse just continued as normal.

This seems like the biggest take-away for me. That is a big difference.

Since you are highly knowledgeable about AP/Mastodon, may I was one more question, if you have a moment?

I believe that one of the neatest things about AT/Bluesky is that each user has their own SQLite DB. This and DIDs makes account portability pretty easy, right? [0]

Where is AP/Mastodon on account portability?

[0] https://news.ycombinator.com/item?id=35881905 (I assume it's progressed since then)

> Where is AP/Mastodon on account portability?

ActivityProtocol doesn't really get involved with "account portability" as far as I understand it. It's a problem the client needs to solve.

In the case of Mastodon it's pretty easy to export your account, import it elsewhere, and set up a redirect. Currently that doesn't carry over posts but there's no real reason why it couldn't.

Mastodon offers to migrate relationships between accounts automatically, so moving both people you follow and people following you. But it doesn't offer post migration between servers. Since it doesn't use anything like DIDs, it'd be pretty hard to reassociate your posts as other servers know them with a new account ID.

I know of one other software, Firefish, that would migrate your old posts, but just not federate them. So you could have the archive of them still attached to your account, they just wouldn't be seen across the network.

Yup, facepalm

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