[wp-hackers] APC-Nginx-Apache problems / memory problems on VPS

[Simon Blackbourn]

Bear in mind that VPS problems are not always down to the setup of your
individual VPS - they can be significantly influenced by the virtualisation
technology itself, especially if the host company hasn't configured it well
or is overselling (which most of the big companies do). Different
virtualisation technologies handle high load scenarios very differently. My
best VPS experience by a mile is with a company here in the UK who use KVM
for virtualisation and who do not oversell.

I'm running a site with YARPP on a small (1gb) VPS that it shares with five
other WordPress sites, in total getting more daily hits than you do, but
I've rarely seen server load go up above 0.2. Most of the time in fact it's
around 0.02, so I don't think YARPP is your main problem. I'm sure it
probably could be more efficient, but you've got other problems to tackle
first.

On a sidenote (but more in line with this list's subject of hacking
WordPress), I became somewhat obsesssed with reducing database queries,
especially on the homepage, and one strategy I've adopted is to use
transients to store the HTML output of various bits of the homepage, such as
all the custom loops (there are 8 loops on the homepage). These transients
are updated on save_post and set to be stored indefinitely, so visits to the
homepage create zero extra database calls outside of the main loop (because
the queries are run in the admin, not on the front end if you see what I
mean). Without this, the homepage was generating something like 200 database
queries, now it's just 20.

Simon

PS - I find Server Density (http://serverdensity.com ) a very useful and
cheap service for monitoring all kinds of things: server load, MySQL, disks,
I/O, CPU, memory, processes, swap, etc. Very easy to set up and works with
Nginx too.