https://github.com/LemmyNet/lemmy/issues/3245
I posted far more details on the issue then I am putting here-
But, just to bring some math in- with the current full-mesh federation model, assuming 10,000 instances-
That will require nearly 50 million connections.
Each comment. Each vote. Each post, will have to be sent 50 million seperate times.
In the purposed hub-spoke model, We can reduce that by over 99%, so that each post/vote/comment/etc, only has to be sent 10,000 times (plus n*(n-1)/2 times, where n = number of hub servers).
The current full mesh architecture will not scale. I predict, exponential growth will continue to occur.
Let’s work on a solution to this problem together.
But, just to bring some math in- with the current full-mesh federation model, assuming 10,000 instances-
That will require nearly 50 million connections.
Each comment. Each vote. Each post, will have to be sent 50 million seperate times.
Well your whole premise is just utterly wrong.
The way federation actually works:
A user on lemmy.ml subscribes to a community on lemmy.world. Say, !funny@lemmy.world
Assume that this user is the first lemmy.ml user to do so - basically what happens is the lemmy.world community sees that a member of a never before seen instance just subscribed. !funny@lemmy.world then adds lemmy.ml to its list of instances it needs to tell whenever something happens in the community.
No matter how many users of lemmy.ml subscribe, this only happens once.
Now when a user of sh.itjust.works upvotes a post on !funny@lemmy.world, the sh.itjust.works instance then tells !funny@lemmy.world of this change. It accepts the change, then tells everyone on its list of instances that have subscribers on them.
So essentially, sh.itjust.works talks to lemmy.world, lemmy.world tells everyone else. There is no “full mesh”. The instance hosting the community is the “hub”, everything else is a spoke.
So if there’s 10,000 instances, and they all just so happen to have at least one subscriber to some community, each change will be sent out 9,999 times. Your “50 million” premise is just completely wrong and I’m not sure where it’s coming from.
Its not wrong- we just have opposite ideas here-
The 50 million, is based on the formula for a full-mesh network. Where all instances talk to each other. In the case of lemmy, this would be an absolute worst-case scenario, where every instance, is subscribed to a community on every other instance.
In your example of only 10,000 messages, you are assuming that of the 10,000 instances in existence, they are ONLY looking at a single community, on a single server.
Lets say, those 10,000 instances all decide to look at a community on another server. Now you have 20,000 connections.
Lets add another community, hosted on yet another instance. That is 30,000 connections.
TLDR;
My example, is based on worst-case scenario. (A pretty unachievable one at that!)
Your example, is based on best-case scenario.
Realistically, the actual outcome would be somewhere much closer to best-case scenario(As communities seem to lump up on the big servers). However, for planning architecture, you always assume worse-case scenario.
No - you said:
Each comment. Each vote. Each post, will have to be sent 50 million seperate times.
That won’t ever happen. Unless there’s 50 million instances. That’s not worst case, it’s just not a case.
There is no case in the current implementation where any one action is replicated more times than there are total instances.
And it doesn’t matter what “model” you assume, each action will have to federate to each instance eventually. That count is minimally, the total number of instances.
Lets say, those 10,000 instances all decide to look at a community on another server. Now you have 20,000 connections.
Looking does nothing, each instance hosts essentially a copy of the “host instance” for each community. Only interactions (comments, likes, posts, etc) are federated.
for fucks sake, dude, be collaborative, and not defensive. This isn’t reddit, I am not out to attack your karma.
If every instance, hosts a community, and Every other instance, subscribes to every one of those communities, that would lead to a full-mesh between all instances, resulting in worst-case scenario, ie, following the formula I provided for a full-mesh topology.
That is indeed, the worst case scenario, I have provided, explained, and documented in my examples.
If my example is too hard to understand, lets use an easier example
Count the number of instances on https://lemmy.ml/instances
Assume every one of those instances subscribes to !asklemmy.
Now, count the number of instances on https://lemmy.world/instances
Assume, every one of those instances subscribes to !lemmyworld.
Now, count the number of instances on https://beehaw.org/instances
Assume, every one of those instances subscribes to !technology.
It does. not. scale.
