Lemmy PERFORMANCE CRISIS: popular instances with many remote instances following big communities could stop federating outbound for Votes on comments/posts - code path identified
I spent several hours tracing in production (updating the code a dozen times with extra logging) to identify the actual path the lemmy_server code uses for outbound federation of votes to subscribed servers.
Major popular servers, Beehaw, Leemy.world, Lemmy.ml - have a large number of instance servers subscribing to their communities to get copies of every post/comment. Comment votes/likes are the most common activity, and it is proposed that during the PERFORMANCE CRISIS that outbound vote/like sharing be turned off by these overwhelmed servers.
Somewhat related, but why are we federating votes? Why not just federate the upvote count and downvote count? Does each server need to track the identity of every voter on a subscribed community?
Each server will track votes from their own users, preventing duplicate votes.