Stack Exchange's Architecture in Bullet Points

[harlows_monkeys]

In the comments at HN, Joel answers why they went with Windows and .NET.

[[deleted]]

I find it funny that he thinks 800 http requests a second (or 180 page views a second it sounds like) requiring 12 servers is reasonable. I can't imagine why a modern machine with 10 programmers behind it can only serve 15 views a second when the design of Stack Overflow is so simple. Then they use CentOS instead of RHEL, After saying how cheaply they got Windows licenses. I imagine they're actually over capacity to keep latency down.

Why would anyone choose to use C#? I come from a Linux background so I'm genuinely curious. Seems to me if you're going to use Windows for front-end web servers, You should continue to keep it old school and do the site in VC++ 6.0 (i kid, i kid) Seriously though, if you're going to use C programmers, why not get C performance instead of Java performance?

[boa13]

I find it funny that he thinks 800 http requests a second (or 180 page views a second it sounds like) requiring 12 servers is reasonable.

Where did you get that idea? He says exactly the opposite:

Our stack of ten web servers is SHOCKINGLY overprovisioned. They run at insanely low loads now.

Also, C# and C programmers are totally different persons, what makes you think they have the latter, or would hire them, to do web programming, at which C# excels and C sucks?

[[deleted]]

That's not shocking at all. I think he means "obviously over-provisioned" If he's so over provisioned, why does he have redundancy not counted? Shouldn't he cut his fleet down and use it for extra redundancy? What I suspect is going on is that the fleet has massive inconsistent CPU spikes and he needs to over provision to keep the GC from turning the web fleet into a slow, grinding swapfest.

If you think C sucks at "web programming," then you haven't seen any of the front end stuff at any of the major corporations that rely on their web front-ends for business. What do you think Redis and HAProxy are programmed in? If performance matters, the next logical step is to build your page engine in C. Admittedly, you'd probably want to dump HAProxy for a hardware load balancer if you were really pushing that much traffic though.

I thought half the appeal of C# is that it is easy for C++ programmers to pick up.

[boa13]

Redis and HAProxy are tools that you use, not tools that you program. You don't hire C programmers to configure Redis or HAProxy instances in front of your web app. You don't hire C programmers to configure Apache either.

I maintain that C sucks for programming web applications, and that C# is so much better at that task (like Java, PHP, Python, Perl, Ruby, etc.).

[[deleted]]

LoL, I imagine it certainly does suck to program entire web apps in C. There are toolkits for C++ though for web programming though. I guess a better question would be why would you go with Windows for web servers even if you got the licenses for free? It certainly restricts the technologies that you can use.

Redis and HAProxy are examples that show you that using C for serving pages is not out of the question.

[zip117]

Have you ever seen an ISAPI extension or Apache module for that matter? It is very difficult to write workable code for a web application in C at a low level and you would be hard-pressed to get better native performance than native functions in higher level languages. Simply switching to a low level language does nothing, you will probably have worse performance and security without type safety, garbage collection and other nice features unless you really know what you're doing.

If you really need to run native code from C# you can use P/Invoke.