Ok, so I have some code to crawl a posting of a community and compare two servers for comments missing. It looks bad today. Both of these servers are version 0.18.0 and have been upgraded for several days.
missing 0 unequal 0 11 on https://lemmy.ml/ vs. 11 on https://sh.itjust.works/
missing 35 unequal 1 48 on https://lemmy.ml/ vs. 14 on https://sh.itjust.works/
missing 4 unequal 0 9 on https://lemmy.ml/ vs. 5 on https://sh.itjust.works/
missing 6 unequal 0 9 on https://lemmy.ml/ vs. 3 on https://sh.itjust.works/
missing 1 unequal 0 1 on https://lemmy.ml/ vs. 0 on https://sh.itjust.works/
missing 6 unequal 0 12 on https://lemmy.ml/ vs. 6 on https://sh.itjust.works/
missing 3 unequal 0 8 on https://lemmy.ml/ vs. 5 on https://sh.itjust.works/
missing 3 unequal 0 6 on https://lemmy.ml/ vs. 4 on https://sh.itjust.works/
missing 22 unequal 0 42 on https://lemmy.ml/ vs. 20 on https://sh.itjust.works/
missing 5 unequal 0 15 on https://lemmy.ml/ vs. 10 on https://sh.itjust.works/
missing 8 unequal 2 17 on https://lemmy.ml/ vs. 9 on https://sh.itjust.works/
missing 3 unequal 0 3 on https://lemmy.ml/ vs. 0 on https://sh.itjust.works/
missing 0 unequal 0 10 on https://lemmy.ml/ vs. 10 on https://sh.itjust.works/
missing 11 unequal 0 24 on https://lemmy.ml/ vs. 13 on https://sh.itjust.works/
missing 1 unequal 0 2 on https://lemmy.ml/ vs. 1 on https://sh.itjust.works/
missing 13 unequal 0 37 on https://lemmy.ml/ vs. 24 on https://sh.itjust.works/
missing 3 unequal 0 7 on https://lemmy.ml/ vs. 4 on https://sh.itjust.works/
missing 0 unequal 0 10 on https://lemmy.ml/ vs. 10 on https://sh.itjust.works/
missing 60 unequal 2 186 on https://lemmy.ml/ vs. 126 on https://sh.itjust.works/
missing 10 unequal 2 51 on https://lemmy.ml/ vs. 41 on https://sh.itjust.works/
missing 16 unequal 0 51 on https://lemmy.ml/ vs. 36 on https://sh.itjust.works/
missing 31 unequal 3 128 on https://lemmy.ml/ vs. 97 on https://sh.itjust.works/
missing 0 unequal 0 4 on https://lemmy.ml/ vs. 4 on https://sh.itjust.works/
missing 2 unequal 0 5 on https://lemmy.ml/ vs. 3 on https://sh.itjust.works/
missing 15 unequal 1 67 on https://lemmy.ml/ vs. 52 on https://sh.itjust.works/
missing 4 unequal 0 53 on https://lemmy.ml/ vs. 49 on https://sh.itjust.works/
missing 0 unequal 0 5 on https://lemmy.ml/ vs. 5 on https://sh.itjust.works/
missing 0 unequal 0 0 on https://lemmy.ml/ vs. 0 on https://sh.itjust.works/
missing 1 unequal 0 19 on https://lemmy.ml/ vs. 18 on https://sh.itjust.works/
missing 0 unequal 0 2 on https://lemmy.ml/ vs. 2 on https://sh.itjust.works/
missing 0 unequal 0 22 on https://lemmy.ml/ vs. 22 on https://sh.itjust.works/
missing 0 unequal 0 16 on https://lemmy.ml/ vs. 18 on https://sh.itjust.works/
missing 0 unequal 0 7 on https://lemmy.ml/ vs. 7 on https://sh.itjust.works/
missing 3 unequal 0 27 on https://lemmy.ml/ vs. 24 on https://sh.itjust.works/
missing 2 unequal 0 32 on https://lemmy.ml/ vs. 30 on https://sh.itjust.works/
missing 3 unequal 0 21 on https://lemmy.ml/ vs. 18 on https://sh.itjust.works/
missing 3 unequal 1 16 on https://lemmy.ml/ vs. 13 on https://sh.itjust.works/
missing 3 unequal 1 47 on https://lemmy.ml/ vs. 44 on https://sh.itjust.works/
missing 1 unequal 0 24 on https://lemmy.ml/ vs. 23 on https://sh.itjust.works/
The number of comments is based on loading comments, not the counts at the top of the posting.
I wonder if some instances are more prone to drop comments that others? have you looked for example at lemmy.world (very large but performant) and another relatively small instance?
have you looked for example at lemmy.world (very large but performant) and another relatively small instance?
Yes, and I run my own instance that is on a high performance server and it has no users other than myself for testing Lemmy.
Lemmy.ml is having the most problems, but really all of the big servers are dropping comment and post replication. The biggest problem is that server operators have no way to know this is happening other than to read raw Linux error logs. The post ID numbers are unique to each server, so it is not easy to identify which link is for the same postings.
I think I saw one of your earlier posts and I really appreciate you chasing this down and raising awareness. As a relatively savvy user this is definitely something I’ve noticed and I share your concern that it will slowly erode user’s trust in the concept of federation.
Technically, can you trace where the comments are dropped? does the target receive the response but fails to process it, or does it break somewhere at the network layer? if so, is there no receiver “ack” built into the protocol? sorry for asking a bunch of questions and feel free to ignore (I’m an engineer but I don’t know much about the federation protocol…)
Technically, can you trace where the comments are dropped?
There are multiple timing and resource issues with the way content is sent. Every single vote and comment has a lot of overhead, and the Lemmy servers are causing each other to slow down with the overhead of it all. There are even very tight security timings that have been hit causing rejection. And there system has no automated way to repair missing content, it just tires to keep up with each new posting, comment, vote.
