
Stack Overflow: The Architecture – 2016 Edition - Nick-Craver
http://nickcraver.com/blog/2016/02/17/stack-overflow-the-architecture-2016-edition/
======
caleblloyd
"During peak, we have about 500,000 concurrent websocket connections open.
That’s a lot of browsers. Fun fact: some of those browsers have been open for
over 18 months. We’re not sure why. Someone should go check if those
developers are still alive."

It's impressive that SO held the connection open for 18 months! That's some
seriously good uptime for a process that manages a TCP connection.

~~~
ksec
Strange, no wonder why some Browsers stats are stuck with old versions.

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codeulike
They have 11 IIS servers but interestingly he says this:

 _What do we need to run Stack Overflow? That hasn’t changed much since 2013,
but due to the optimizations and new hardware mentioned above, we’re down to
needing only 1 web server. We have unintentionally tested this, successfully,
a few times. To be clear: I’m saying it works. I’m not saying it’s a good
idea. It’s fun though, every time._

~~~
seanp2k2
Interesting to consider how some companies doing much less work on their
machines than SO need clusters of hundreds of servers, meanwhile they can
serve the 57th site by global traffic (according to Alexa) from _one physical
machine_ .

Sure there is other stuff backing that one, but the next time you hear someone
talk about big clusters and hundreds or thousands of nodes, just take a moment
to appreciate how much can be done with one rack of gear these days.

~~~
daxfohl
Granted it's a machine with 768 GB RAM.

~~~
XenophileJKO
It's only got 64GB if I read data center upgrade post from 2015 correctly.

"The new web tier has dual Intel 2687W v3 processors and 64GB of DDR4 memory.
We re-used the same dual Intel 320 300GB SSDs for the OS RAID 1."

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charlieegan3
Wish more sites/companies/employees published this sort of information -
really interesting stuff.

Are there any other examples of big (largely) Windows stacks? Stack Exchange
is the only one I've seen discussed.

~~~
lobster_johnson
Todd Hoff's High Scalability [1] is a very nice blog to follow if you like
this kind of information about real-world stacks. He's been writing it for
years. (Caveat: It's a while since I followed it closely.)

[1] [http://highscalability.com/](http://highscalability.com/)

~~~
dikaiosune
Stuff the Internet Says on Scalability is an excellent weekly article he does
with plenty of great resources. Lots of stuff that's just reposted from HN,
but also many pieces on real-world architectures that I never see on HN or
/r/programming.

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mschuster91
> Fun fact: some of those browsers have been open for over 18 months. We’re
> not sure why. Someone should go check if those developers are still alive.

How is that actually possible to keep a single TCP/IP connection open over 18
months?!

~~~
jewel
Someone probably opened up a browser on a server to look something up and then
left it running. With a static IP and battery backup, only a reboot is likely
to take it down. The connection should be able to survive short outages due to
a firewall restart or momentary problem upstream, especially if there's no NAT
in between.

I'm using SSH's ControlMaster in persistent mode on my desktop at work. The
connections stay open for as long as the desktop is up, which can be months at
a time.

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paulftw
So it's 125 million SQL queries or 6 million page loads per machine per day.

It also seems like average query is 1.2ms - am I missing something?

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eleitl
Why the Windows stack though?

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augustl
Jeff Atwood and Joel Spolsky have their roots in the Windows community, so
they used what they were familiar with.

