Asynchronous

[Dave Aitel <dave () immunityinc com>]

So while I'm in the process of running a large asynchronous event-driven
product in a VM in another window, it's a good time to read all sorts of
things about asynchronous programming.

Frankly, I'm not a huge fan of it, but Chris is, and he's a better
programmer than me, so we'll leave it at that. Largely, I think people
are fans of Async because most languages and kernels are terrible at
threads. Python, for example, does not have threads. "No worky worky",
as we say around here.

The downside of async is that it is basically impossible to debug, and
you need a programmer as good as Chris to even begin to use it well.
Likewise, the locking/blocking problems don't go away, they just get
mapped into a more inscrutable form.

So for systems that have working threads, you use them for anything
IO-heavy (aka, web servers/crawlers/other useful hacking tools). But
since almost no system HAS working, scalable, threads, people get
excited about async.  And then you spend your whole life saying "Hey,
this thing I do sometimes has to do a lot of work on the CPU, so let's
put it in another thread please". Or "Hey, this whole giant DB library
we have to use isn't built from the ground up to use Async, so we need
it to be in its own thread and manage a feeder Queue to it".

And then eventually you're like "Why on earth am I spending so much time
worrying about how efficient an algorithm that runs on one machine is?"
and you go off and build something that scales horizontally onto
multiple machines. (Where "multiple" is > 100).

But in the meantime you have things like asyncore and Node.js and stuff.
I can't do them justice, but these posts below are the funniest thing
you'll read since Steve Yegge <http://steve-yegge.blogspot.com/>.

http://teddziuba.com/2011/10/node-js-is-cancer.html
http://teddziuba.com/2011/10/straight-talk-on-event-loops.html
http://www.unlimitednovelty.com/2011/10/nodejs-has-jumped-shark.html

-dave

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