We'll have these posts which get a large number of comments, and finally they hit some wall and we get errors like this:
[Mon Sep 13 05:05:48 2010] [error] [client 188.8.131.52] PHP Fatal error: Allowed memory size of 52428800 bytes exhausted (tried to allocate 275282 bytes) in /home/unprofes/www/wp-content/plugins/w3-total-cache/inc/define.php on line 233. That line is checking to see if the content is xml or html.
That's fine, I can resize my server to get more space and see what is happening. But what's interesting is I could not figure out what caching method was causing this (page cache, database, etc), so I disabled *all* the caching, and I was still getting this message.
I ended up having to Deactivate the plugin to make the error message go away.
Two things: 1) This seems to be a slightly excessive way to check for xml vs. http, by reading the entire string. May be better off grabbing the first chunk of data; and 2) Why did I have to deactivate the plugin and not just disable it to make it stop executing part of its code?