Hi,

I have been a very happy customer of LunarPages for several years, but for the first time last week I got the dreaded email from support saying that they had to rename one of my scripts because it was using too many CPU resources.

Well, when I looked, the "script" was the index.php file for WordPress -- i.e. they had taken the whole blog down.  From reading the forum, I can see that they can't pinpoint which PHP file is causing the problem (is that still true?) so it's no surprise that they had to disable the main entry point for the whole of Wordpress.

What's very puzzling though is that the WordPress installation had not been modified or changed in any way (except for new blog posts a couple of times a week) for months and had, I assumed, been running with no problems. The blog only gets about 30-40 visits a day, and about 100 page views, so it's not heavily used blog.  I have checked through the installation and all the available states and logs, and have found nothing to indicate that it have been attacked or hacked in any way, so I am left with the assumption that something caused something in WordPress to start misbehaving all of a sudden.

I am working with support on this problem, but I was wondering if anyone has had similar issues with their WordPress blogs on LP, and if they found a solution.  The installation was out of date -- WP 2.5 -- but since there had not been any issues up till last week, I don't see how that would be a problem.  I have upgraded to WP 2.9.2 which is the very latest version, and upgraded all the plugins too.  I have also updated my sitemap.xml, added a much better robots.xml, and disabled hotlinking, though there was no evidence that any of these was causing a problem.

I also have a general question about CPU usage.  In LP support's last reply, they listed three incidents of high CPU usage.  The first one I could tell occurred when I told Wordpress to upgrade about a dozen different plugins all at once on one of my blogs (not the one that was disabled).  It took about a minute to complete, and it seems it caused a peak load of 93%.  I understand that's very high, but it was a one-off activity on a blog that has not been active at all -- no readers, no posts -- for months.  

So my question Is something like that likely to get me into trouble on its own, or does it have to be a pattern of high CPU usage over a period of, say 10 minutes, 30 minutes, or an hour, or something?  (In this case, I could probably have avoided the spike by upgrading the plugins one at a time, but I would like to know if that's necessary or not.)

I fully understand that on a shared system, CPU cycles must be kept under control, but with a large script installation like Wordpress, you are sometimes at the mercy of the WP developers, and more likely the WP plugin developers, and since a blog with only a few dozen readers a day (at most) should not be causing a heavy load on the LP servers, I am looking for any guidance anyone can give to help avoid this situation in the future.

Cheers,

Mike

P.S. I should add that I appreciate LP Support's perseverance on this matter, and the fact that they didn't just suspend my account completely because of the problems.  I will continue to work with them to find a solution to the problem.

I highly recommend using the WP cache plugin. It's excellent at reducing the load on the server.

Did you thoroughly go through your site before making that statement? Have you at least looked at the "last modified" date on all your files, and accounted for any new files? Just because your blog didn't go belly up, or engage in any other obviously bad behavior, doesn't mean it isn't being exploited to do something nasty (spamming, DDoS attacks, etc.). It could well be your plug-in update that's the culprit, but more often than not, it's because a site has been hacked, especially if it's quite back-level. Just because it's still functioning at its original purpose doesn't mean it's not doing other things now...

If you don't have command line access (SSH), run a one-time cron job: ls -alR . This will list all your files along with sizes and last-modified dates. I run this on a regular basis, comparing the current listing with the previous to see what's changed (and investigating any unexpected changes). You can limit it to the site itself with ls -alR public_html .