April is here and we’re still enjoying our little corner of the lemmy-verse! This post is quite late for our April announcement as my chocolate coma has only now subsided
Donations
Due to some recent huge donations recently on our Ko-Fi we decided to migrate our database from our previous big server to a dedicated database server. The idea behind this move was to allow our database to respond faster with a faster CPU. It was a 3.5GHz cpu rather than what we had which was a 3.0GHz. This, as we know, did not pan out as we expected.After that fell through we have now migrated everything to 1 huge VPS in a completely different hosting company (OVH).
Since the last update I used the donations towards setting up an EU proxy to filter out down votes & spam as a way to try and respond faster to allow us to catch up. We’ve purchased the new VPS from OVH (which came out of the Ko-Fi money), & did the test of the separate database server in our previous hosting company.
Our Donations as of (7th of April):
- Ko-Fi: $280.00
- OpenCollective: $691.55 (of that 54.86 is pending payment)
Threads Federation
Straight off the bat, I’d like to say thank you for those voicing your opinions on the Thread federation post. While we had more people who were opposed to federation and have since deleted their accounts or moved communities because of the uncertainty, I left the thread pinned for over a week as I wanted to make sure that everyone could respond and have a general consensus. Many people bought great points forward, and we have decided to block Threads. The reasoning behind blocking them boils down to:
- Enforced one-way communication, allowing threads users to post in our communities without being able to respond to comments
- Known lack of Moderation which would allow for abuse
These two factors alone make it a simple decision on my part. If they allowed for comments on the post to make it back to a threads user then I probably would not explicitly block them. We are an open-first instance and I still stand by that. But when you have a history of abusive users, lack of moderation and actively ensure your users cannot conduct a conversation which by definition would be 2 way. That is enough to tip the scales in my book.
Decision: We will block Threads.net starting immediately.
Overview of what we’ve been tackling over the past 4 weeks
In the past month we’ve:
- Re-configured our database to ensure it could accept activities as fast as possible (twice!)
- Attempted to move all lemmy apps to a separate server to allow the database to have full use of our resources
- Purchased an absurd amount of cpus for a month to give everything a lot of cpu to play with
- Setup a haproxy with a lua-script in Amsterdam to filter out all ‘bad’ requests
- Worked with the LW Infra team to help test the Amsterdam proxy
- Rebuilt custom docker containers for added logging
- Optimised our nginx proxies
- Investigated the relationship between network latency and response times
- Figured out the maximum 3r/s rate of activities and notified the Lemmy Admin matrix channel, created bug reports etc.
- Migrated our 3 servers from one hosting company to 1 big server at another company this post
This has been a wild ride and I want to say thanks to everyone who’s stuck with us, reached out to think of ideas, or send me a donation with a beautiful message.
The 500 mile problem (Why it’s happening for LemmyWorld & Reddthat)
There are a few causes of this and why it effects Reddthat and a very small number of other instances but the main one is network latency. The distance between Australia (where Reddthat is hosted) and Europe/Americas is approximately 200-300ms. That means the current ‘maximum’ number of requests that a Lemmy instance can generate is approximate 3 requests per second. This assumes a few things such as responding instantly but is a good guideline.
Fortunately for the lemmy-verse, most of the instances that everyone can join are centralised to the EU/US areas which have very low latency. The network distance between Paris and Amsterdam is about 10ms. This means any instances that exist in close proximity can have an order of magnitude of activities generated before they lag behind. It goes from 3r/s to 100r/s
- Servers in EU<->EU can generate between 50-100r/s without lagging
- Servers in EU<->US can generate between 10-12r/s without lagging
- Servers in EU<->AU can generate between 2-3r/s without lagging
Already we have a practical maximum of 100r/s that an instance can generate before everyone on planet earth lags behind.
Currently (as of writing) Lemmy needs to process every activity sequentially. This ensures consistency between votes, edits, comments, etc. Allowing activities to be received out-of-order brings a huge amount of complexity which everyone is trying to solve to allow for all of us (Reddthat et al.) to no longer start lagging. There is a huge discussion on the git issue tracker of Lemmy if you wish to see how it is progressing.
As I said previously this assumes we respond in near real-time with no processing time. In reality, no one does, and there are a heap of reasons because of that. The biggest culprit of blocking in the activity threads I have found (and I could be wrong) is/was the metadata enrichment when new posts are added. So you get a nice Title, Subtitle and an image for all the links you add. Recent logs show it blocks adding post activities from anywhere between 1s to 10+ seconds! Since 0.19.4-beta.2 (which we are running as of this post) this no longer happens so for all new posts we will no longer have a 5-10s wait time. You might not have image displayed immediately when a Link is submitted, but it will still be enriched within a few seconds. Unfortunately this is only 1 piece of the puzzel and does not solve the issue. Out of the previous 24hours ~90% of all recieved activities are related to votes. Posts are in the single percentage, a rounding error.
This heading is in reference to the 500 miles email.
Requests here mean Lemmy “Activities”, which are likes, posts, edits, comments, etc.
So … are we okay now?
It is a boring answer but we wait and enjoy what the rest of the fediverse has to offer. This (now) only affects votes between LemmyWorld to Reddthat. All communities on Reddthat are successfully federating to all external parties so your comments and votes are being seen throughout the fediverse. There are still plenty of users in the fediverse who enjoy the content we create, who interact with us and are pleasant human beings. This only affects votes because of our forcing federation crawler which automatically syncs all LW posts and comments. We’ve been “up-to-date” for over 2 weeks now.
It is unfortunate that we are the ones to be the most affected. It’s always a lot more fun being on the outside looking in, thinking about what they are dealing with and theorising solutions. Knowing my fellow Lemmy.nz and aussie.zone were affected by these issues really cemented the network latency issue and was a brilliant light bulb moment. I’ve had some hard nights recently trying to manage my life and looking into the problems that are effecting Reddthat. If I was dealing with these issues in isolation I’m not sure I would have come to these conclusions, so thank you our amazing Admin Team!
New versions means new features (Local Communities & Videos)
As we’ve updated to a beta version of 0.19.4 to get the metadata patches, we’ve already found bugs in Lemmy (or regressions) and you will notice if you use Jerboa as a client. Unfortunately, rolling back isn’t advisable and as such we’ll try and get the issues resolved so Jerboa can work.
We now have ability to change and create any community to be “Local Only”.
With the migration comes support for Video uploads, Limited to under 20MB and 10000 frames (~6 minutes)! I suggest if you want to shared video links to tag it with [Video] as it seems videos on some clients don’t always show it correctly.
Thoughts
Everyday I strive to learn about new things, and it has certainly been a learning experience! I started Reddthat with knowing enough of alternate technologies, but nearly nothing of rust nor postgres. 😅
We’ve found possibly a crucial bug in the foundation of Lemmy which hinders federation, workarounds, and found not all VPS providers are the same. I explained the issues in the hosting migration post. Learnt a lot about postgres and tested postgres v15 to v16 upgrade processes so everyone who uses the lemmy-ansible repository can benefit.
I’m looking forward to a relaxing April compared to the hectic March but I foresee some issues relating to the 0.19.4 release, which was meant to be released in the next week or so. 🤷
Cheers,
Tiff
PS. Since Lemmy version 0.19 you can block an instance yourself without requiring us to defederate via going to your Profile, clicking Blocks, and entering in the instance you wish to be blocked.
Fun Graphs:
Instance Response Times:
Data Transfers:
I figured zero votes was some federation issue. I also encounter another issue. Delayed notifications. I use sync for lemmy. The notifications for comments from lemmy.world users arrive late. Sometimes 5-7days late. That’s the only instance I know where this is significant.
The way we “force federation” is to tell reddthat to “resolve” the comment/post via the API. It’s a roundabout way to force all of the content to still appear.
It’s interesting that it doesn’t trigger notifications but I’m not surprised it doesn’t and when you think about it makes some sort of sense.
The 5-7 day delay is when the actual comment/post is federated from LW as the “time behind” value is 6.3 days currently (and coming down).
I’m reaching out to one of the other admins who apparently wrote their own federation queue. That means we could return a 200 OK response instantly for everything and work on the queue on our own time.
There is still not that much movement on the dev side as it’s a complex problem and the devs don’t seem to want to develop something like a queue currently. Which I understand as it would be a completely new system and would need lots of testing…On-top of that, every “jump” in backlog results from some abusive kbin bugs. Kbin has some users who send a like and an unlike constantly. In the order of 50k requests in an hour. They like and unlike a post on LW. LW then has to federate ever like and unlike activity. Which ends up being 50k Activites that need to be sent per-server. So it makes federation lag for everyone.
So we’ve managed to catch-up a bit each day and then some kbin bug causes an issue and then we are now +1 extra day behind.
Hearing about the lack of notifications is disheartening. Is it so hard for a system to have some sort of quorum? :(
Hopefully we get something sorted in the next week or two… Otherwise I might block every vote coming in until we catch-up. (As votes account for over 90% of activities).
Tiff
The 5-7 day delay is when the actual comment/post is federated from LW as the “time behind” value is 6.3 days currently (and coming down).
Interesting.
Hearing about the lack of notifications is disheartening. Is it so hard for a system to have some sort of quorum? :(
Federation at scale appears to be very complex. But, through these challenges and all one grows. Lemmy is the best thing since reddit or especially after reddit.
Hopefully we get something sorted in the next week or two… Otherwise I might block every vote coming in until we catch-up. (As votes account for over 90% of activities).
🤞
Just wanted to tell you thank you for hosting us! I’m no good at doing recurring donations, but I’m more than happy to throw a little something when I’ve got some extra. Hope every little bit helps create something for everyone. Thanks as always!
Every bit will be used for copious amounts of coffee! 😜. The old server got really cranky, but this new one is raring to go! (Except for this db/pagination issue, but I think I found a good way to investigate).
Thankyou so much!
Good job as always! Love reading the technicals although most of it goes over my head.
I’ll test out the video upload here in a bit. Very excited as I have thought this was a serious feature Lemmy was lacking.
I had spent some time thinking about the potential Threads federation and I’ve formed a strong opinion. I’d rather we keep defederated (for now).
Moderation/Zuck ownership concerns aside, which others have already raised, Threads’s userbase is orders of magnitude greater than Reddthat. The possibility of Embrace, Extend, Extinguish is very real if XMPP’s history is any indication. That being said, I’m not fully against Threads federation with Lemmy as a whole. I’ll just say that I don’t trust that if we federate with them now, it would be a net gain to Reddthat’s userbase. I think the instance’s open-first policy is suited for communities of a similar magnitude of activity/userbase to us that may not necessarily work with respect to Mastodon or Threads.
I’m rather adamant on “observe, and trust, and verify”. lemmy.world is federated with Threads. Let’s see how that goes for them, whether if they’re better or worse off with that, then we reconsider. In this regard, I view the lemmy.world/Threads interaction as a “controlled endpoint of interaction” between these systems. If users really want to see Threads content in Lemmy, consider adding a lemmy.world account in addition to your Reddthat one.
Thank you for articulating your thoughts. I always enjoy hearing the views of our users! I too will be looking at how this progresses. The more people we can migrate to the fediverse the better!
Though I can’t recommend getting a LW account 😛, purely because I want everyone on Reddthat. I think if you want to investigate Threads/etc, a mastodon type account would be the best course of action. As following single accounts on Lemmy is… non existent (I don’t count RSS feeds).
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Oh for threads.net? Once that happens I plan to re-evaluate how everyone feels.
If at the end of the day people feel strongly enough against it then we will keep it but I hope to open it back up again. As (I think) the defed only affects our communities, not content people post to other instances’ communities.
Thank you for the great update!
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