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Hi,
Barry Abrahamson here. A bit of context to my comment about the stability of Apache. We started WordPress.com using the Litespeed web server, but decided that we wanted to maintain as much of an open source stack as possible. We looked at lighttpd but had lots of issues with memory usage (leaks?) so we naturally turned to Apache. It worked mostly as expected performance and functionality wise. Keep in mind this was back in the Apache 2.0 days. Our problem was that deploying configuration changes which required a graceful restart under production traffic levels didn't work very well. About 10% of the time it either failed to reload the configuration, Apache stopped responding completely, or connections were dropped. Keep in mind that we were reloading ~1000 machines at once, but 10% is a pretty high failure rate. Yes, I know we could have removed machines from production, reloaded the configuration, and then put them back, but it's slow and error-prone, even if automated.
This is when we started looking at nginx. The nginx configuration reload works as expected all of the time, so that was enough to make us invest more time in the software. The transition was non-trivial since we had thousands of lines of .htaccess files which had to be translated to nginx configs, but it was worth it. Today, nginx is the "Swiss Army Knife" of our software stack. We use it for everything we can. I joke that we would use it as a database server if we could :)
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As a side note, this may be the first useful comment on a Wired article I've ever seen.