I have burned a few days on this. I have a blog running on FreeBSD / Apache / PHP4 / MySQL and I wanted to try tunning it on a new host, which is a virtual Ubuntu Hardy LTS . . .
So, I install MySQL5, PHP5, Apache22, copy the files over, export the database from the old host and load it in on the new host . . .
Things work pretty well at first: I can get the front page and click on individual entries. If I enable certain plugins or after clicking on a second category page things go all to hell: the request locks up completely and nothing happens. Sometimes I'll get a timeout message from PHP, sometimes not.
Since the new host has only 256M I tried swapping out Apache2 in favor of lighthttpd. So, now there's no swapping but I still have similar issues: request spin off into nowhere.
When this happens, I can observe:
* NO long-running SQL queries.
On Apache, I see:
* The entire site tends to lock up.
* /etc/init.d/apache2 restart will complete but the old Apache doesn't actually stop. I have to kill -9 apache2. :(
* /etc/init.d/lighthttpd restart works fine . . .
* BUT a pool of php-cgi processes hang around.
* I can usually get one category page after restarting things.
* If I request a second category page it'll lock up, but the site is still responsive. I can hit "back" and select individual page URLs.
So, as best I can tell there is something nasty going on between WordPress and Ubuntu's PHP5. Is it WordPress or something specific to my site? In order to get things running I did have to manually enter mysql and change the URL values in the options table to WordPress would redirect back to my existing site . . .
Any insight would be vastly appreciated. Thanks!