this post was submitted on 11 Aug 2023
220 points (98.2% liked)

Fediverse

28724 readers
110 users here now

A community to talk about the Fediverse and all it's related services using ActivityPub (Mastodon, Lemmy, KBin, etc).

If you wanted to get help with moderating your own community then head over to [email protected]!

Rules

Learn more at these websites: Join The Fediverse Wiki, Fediverse.info, Wikipedia Page, The Federation Info (Stats), FediDB (Stats), Sub Rehab (Reddit Migration), Search Lemmy

founded 2 years ago
MODERATORS
 
you are viewing a single comment's thread
view the rest of the comments
[–] [email protected] 4 points 1 year ago (1 children)

Getting the total number of all comments may be very resource heavy if there is a lot of comments.

If it's just 5 comments, then the computer can quickly get them all from database and count how many of them are there. Now imagine if there is 50 000 comments and suddenly, you me and entire website ask "how many comments are there for this post?"

Suddenly the computer is overwhelmed by the request and you may end up crashing it due to amount of tasks it has to do.

It's way faster if instead of all of that, the computer kept track of a number of all comments and simply adjust it when comment is added or removed. It does not have to get all the comments and count how many are there, just simply return the number and you are done.

But in the essence, you sacriface potential accuracy for speed. You may accidentally "desynchronize" the counter - if an user requests a removal of the same comment twice, and you don't check if that comment was not removed. Or, in theory, if two separate users add or remove a comment at the same time. This is called "race condition", which is common in multi-threaded computing.