I know that Lemmy is open source and it can only get better from here on out, but I do wonder if any experts can weigh in whether the foundation is well written? Or are we building on top of 4 years worth of tech debt?
It’s decent, but it isn’t scalable, at least not yet.
Right now the entire Lemmy backend is one big “monolith”. One app does everything from logins and signups to posting and commenting. This makes it a little harder to scale, and I wouldn’t be surprised to see it split out into multiple micro services sooner rather than later so some of the bigger instances can scale better.
I’d love to know where the higher level dev stuff is being discussed and if they’ve made a decision on why or why not microservices.
There’s no reason that a monolith can’t scale. In fact you scale a monolith the same way you scale micro services.
The real reason to use micro services is because you can have individual teams own a small set of services. Lemmy isn’t built by a huge corporation though so that doesn’t really make sense.
You definitely can’t scale a monolith the same way you can scale a micro service
You can easily scale a monolith. You typically horizontally replicate any web server (monolith or not) to handle whatever traffic you’re getting. It shouldn’t really matter what type of traffic it is. Plenty of the world’s biggest websites run monoliths in production. You know how people used to say “rails doesn’t scale”? Well they were wrong because Rails monoliths are behind some huge companies like GitHub and Shopify.
The lemmy backend is also quite lightweight and parallel so it’s cheap and effective to replicate.
In my professional experience microservices are usually a dumpster fire from both the dev perspective and an ops perspective (I’m a Site Reliability Engineer).
I disagree that it being a monolith is immediately a problem, but also
In fact you scale a monolith the same way you scale micro services.
This is just not true. With microservices, it is easy to scale out individual services to multiple instances as demand requires them. Hosting a fleet of entire Lemmy instances is far more expensive than just small slices of it that may require the additional processing power.
Lemmy’s backend is native code, not run in a virtual machine or interpreted from text. You’re not going to pay much extra for an extra megabyte or 10 of RAM being used per instance for the extra code sitting idle. It certainly shouldn’t use much processing power when not in use.
What microservices would you split Lemmy into? The database, image hosting and the UI are already separate.
You can easily scale a monolith. You typically horizontally replicate any web server (monolith or not) to handle whatever traffic you’re getting. It shouldn’t really matter what type of traffic it is. Plenty of the world’s biggest websites run monoliths in production. You know how people used to say “rails doesn’t scale”? Well they were wrong because Rails monoliths are behind some huge companies like GitHub and Shopify.
The lemmy backend is also quite lightweight and parallel so it’s cheap and effective to replicate.
In my professional experience microservices are usually a dumpster fire from both the dev perspective and an ops perspective (I’m a Site Reliability Engineer).
Microservices aren’t a silver bullet. There’s likely quite a lot that can be done until we need to split some parts out, and once that happens I expect that federation would be the thing to split out as that’s one of the more “active” parts of the app compared to logins and whatnot.
Definitely not a silver bullet, but should stop the app from locking up when one thing gets overloaded. I’m sure they have their reasons for how it’s designed now and I’m probably missing something that would explain it all.
I’m still not familiar enough with how federation works to speak to how easy that would be. Unfortunately this has happened all as I’ve started moving and I haven’t gotten a chance to dive into code like id want to.
It’s also not the only solution for high-availability system. Multiple monoliths with load-balancing can be used as well.
Also, a lot of people are self-hosting. In this case, microservice won’t give them any scaling benefit.
This is a discussion I’m also interested in. Migrating a monolith to microservices is a big decision that can have serious performance, maintainability and development impact.
Microservices can be very complex and hard to maintain compared to a monolith. Just the deployment and monitoring could turn into a hassle for instance maintainers. Ease of deployment and maintenance is a big deal in a federated environment. Add too much complexity and people won’t want to be part of it.
I’ve seen some teams do hybrids. Like allowing the codebase to be a single artifact or allowing it to be broken by functionalities. That way people can deploy it the easy way or the performant way, as their needs change.
That’s what I’m thinking. Microservices could be a huge pain in the ass, but a hybrid approach would make things much better. Smaller instances wouldn’t be a problem, but the larger instances would be able to separate out components.
To keep it possible to run monolithicly would probably need a lot of work, but it’s possible to do and would probably be the best approach.
Microservices can oftentimes cause more performance issue than they solve, as soon as they need to start talking to each other. Here’s someone with more experience than me explaining how it often goes wrong.
There’s nothing stopping you from putting a load balancer and running multiple instances of a monolith connected to one database. Then the database will also become a bottleneck, but that would still happen with microservices.
Exactly, and nothing prevent a monolith from doing vertical slicing at the database level as long as the monolith is not crossing its boundaries. This is the only scaling part that is inherent to microservices. If the issue is the horizontal scaling, microservices doesn’t solve anything in this case.
Also specifically on what I understand of the Fediverse, you want something easy to host and monitor since a lot of people will roll out their own instances which are known issues when running microservices.
