111–120 of 199 posts
Note that HN, a top-1000 site in the US, runs on a single box via a single racket process. "The key to performance is elegance, not battalions of special cases."
HN is relatively easy to optimise though - there are only a few stories with high traffic, so if you have good caching the load on the back end can be very low. It's more difficult to do that with something like github where the users are spread across millions of repos.
Earlier quoted context omitted.
HN has the luxury of being able to make few high level changes over years, though. It might be tougher to maintain that single box elegance and performance if they were adding new features every month or two (which is much more applicable to the rest of us).
I don't understand this comment. Why should adding features make an app crumble on a single server? I think the point is that good software is able to serve a lot of users on a single server. A great example imho is Blender. Features are added constantly but because the software is modular it doesn't have any impact on the overall performance. Today the problem is that adding features means: adding the latest and gre…
As someone who used to hack on Blender all I can say is it's a big ball of inter-dependent modules all with interlocking dependencies. The only thing that really keeps it manageable is the strict adherence to MVC which, I suppose, does make it modular.
If you liked this page, you might also like the excellent book "Designing Data-Intensive Applications" that among others surveys many characteristics of large-scale systems and presents some. Note that it's not a book for preparing you on system design questions, but it can definitely help.
I've been reading this and it's great so far. Are there other similar books that describe modern enterprise architecture at scale?
I'd add a section on using TLA+ as a design tool. Diagrams and rules of thumb are useful but they don't catch errors or help you discover the correct architecture. See the Amazon paper [0] on their use of TLA+ in designing (and trouble-shooting) services. [0] https://lamport.azurewebsites.net/tla/formal-methods-amazon....
Could you please talk about your experiences with TLA+? The "tools of thinking" for designing and verifying systems really interest me.
Two sender/receivers (sending messages back and forth) and a data bus. For some reason, we seemed to be getting bad data (but not consistently). My "debugging" was actually more like "bugging". I took a correct TLA+ spec, and weakened constraints on different parts until I recreated the behavior we were seeing (it was the data bus). But the nice thing was being able to show that the particular bug couldn't happen from the sender/receivers. Their interaction with the data bus were correct (per the specification) and they were the only parts I could directly inspect (as I didn't have the files on how they implemented the data bus itself).
Once I found the right constraints on the data bus to weaken, I recreated the errors we were seeing in the model itself. This led to devising several more test programs that could more reliably produce the error. From there we were able to better communicate the problem with the contractors involved and get things corrected ("proof" that we weren't the problem).
A particularly nice thing was being able to model abstract versions of the system. I didn't need the fine details (what message specifically is being sent, didn't matter). But I also found I needed more details than my first pass and was able to refine the data bus specification (in TLA+) as needed to provide the necessary level of detail and extend it to add new capabilities.
I hoped this would help me with this problem I have - I'm coding a web app with a smallish database (<1GB for the next few years, <1% writes). I need low latencies for accessing it. And I would like to have multiple servers over the world sharing the database.
you need to provide more details to get any useful advice. but just based on what you have described, any db would do the job. add a caching layer and you have your low latencies. again, what is the traffic and bandwidth load like? peak and average values? what kind of data are you planning to store? small values but huge volumes or the opposite? a lot will change based on your system requirements.
I won't have millions (realistically not even thousands) of users and the database will be comparatively small.
I've looked at NDB cluster but it feels quite complicated to setup and maintain
I see something comparable to these diagrams (it feels like) a half-dozen times a year. The architecture is in general 'fine'. But communication paths of subsystems is probably the easiest part of the problem. And in general, re-organizing the architecture of a system is usually possible - if and only if - the underlying data model is sane. The more important questions are; - What is the convention for addressing ass…
Can we please come up with a more specific name for this type of expertise? A large-scale system can mean anything from a social security system to a rocket. I was a bit disappointed that it only concerns websites here (though I'm aware that I'm browsing HN).
The label is fine. Nobody is confused as to what a "system administrator" is, even though technically the word "system" itself can have a much broader range of meaning.
Large scale systems come in many different shapes and forms; this is an instance of one of them. Its learnings are interdisciplinary and cross-functional, but this isn't the roadmap for other types of systems, especially asynchronous reactive systems.
I see something comparable to these diagrams (it feels like) a half-dozen times a year. The architecture is in general 'fine'. But communication paths of subsystems is probably the easiest part of the problem. And in general, re-organizing the architecture of a system is usually possible - if and only if - the underlying data model is sane. The more important questions are; - What is the convention for addressing ass…
I can answer the above for systems I've built, but I've spent quite a bit of time with those systems. How do I get better at doing this during the planning phases, or even better, for a system I'm unfamiliar with (ie. are there tools you lean on here)?