404 when working in WordPress admin

apps

#1

I have a VPS with DreamHost. In the last few months, I’ve been getting more and more 404s while using WordPress 3.0.4’s administrative interface, such as publishing posts, activating plugins, or approving comments. The only recurring error I see in my error.log file is “Premature end of script headers”. Even the frontend of the site can take 15+ seconds to load, if at all, as indicated by Pingdom Tools. Though I’ve set my VPS’s memory limit to 374 MB, my admin panel rarely shows usage above 247.

I’ve read several threads on similar issues and have followed some suggestions, such as pruning my plugins and adding this line to my wp-config.php file:

define(‘WP_MEMORY_LIMIT’, ‘90M’);

and disabling this line that’s added by DreamHost’s one-click installer:

$base = DB_NAME;

I’ve not installed any caching plugins, as even though I currently run 16 WordPress sites, none of them receives more than double digits of pageviews per day. (Only half accept comments; most have revisions disabled.) I had DreamHost’s Google Pagespeed option enabled for awhile, but it seemed to make things a bit worse, so I disabled it.

With all my plugins enabled, my site makes about 22 queries to load the homepage. The TPC plugin pointed out one instance of high memory usage that involved 38 database queries – presumably while I was accessing the admin panel.

Here are some other statistics reported by the TPC plugin when loading a page:

TPC! Memory Usage (http://webjawns.com)
Memory Usage: 23413816
Memory Peak Usage: 23749872
WP Memory Limit: 90M
PHP Memory Limit: 90M
Checkpoints: 7

From the admin dashboard:

Usage Sample: 30.62MB (12%)
Peak Usage: 30.87MB (12%)
All-Time: 22.33MB on 2/1/11 @ 11:28 pm (wp_head)
Load Averages: 0.23 0.28 0.28
WP Memory Limit: 90M
PHP Memory Limit: 90M

I’ve recently optimized my databases via phpMyAdmin. I also ran a free Load Impact test.

Despite these efforts and diagnoses, my problems persist. Do any of these numbers look unusual? Any suggestions of what I could try that I haven’t already?


#2

Same problem here. Seems to get worse. Any idea?


#3

Surprisingly, I found giving my sites much more RAM than I thought they’d need to solve the problem. More details here:

http://wordpress.org/support/topic/dreamhost-404-when-working-in-admin?replies=19


#4

In various web searches, Dreamhost is the only provider I can find that has this “problem”, and I’m faulting them as using it as a vehicle to push VPS, yet I’ve had this same problem with several WordPress sites from people using VPS, too. The real issue is their overly heavy handed approach to process killing.

WordPress is a pretty standard fixture, and even the most generic ones I have found to exhibit this problem. While every bit of performance has gotten better since a server migration, this one area continues to persist. Removing some lines from the config file seemed to help right away at the time. But it’s creeping back again.