Wordpress wp-cron.php looping and overloading server resources - php

Question

I am working on a site now that seems to have an infinite loop for the wp-cron.php file. My host recently limited my account because they said that a certain query to my database was creating 1GB of error logs every 15 seconds. I am not sure why this is happening.
I wanted to know if anyone has encountered and successfully solved this issue. We were working on this site on a dev server with no problems, but now since we've moved to our production environment we've been getting this issue. I am thinking that maybe some files were lost in the transfer, however it does not seem so.
Thanks

Answer 1

OK So I have found a solution for this, and I figure that it would help to let everyone on here know as well.
Basically, after a lot of research, I have found that the MailChimp Archives plugin apparently fires off the naughty cron job in question every time someone visits the site. For whatever reason, it got thrown into an infinite loop which was creating huge log files (64MB in about 3 seconds). Once I discovered exactly where the issue was coming from, I did the following:
Disabled the plugin
Found a Wordpress function that removes selected hook that schedules the runaway cron job (http://codex.wordpress.org/Function_Reference/wp_clear_scheduled_hook).
Used that function to remove the hook in question, by inserting it into my theme's functions.php file, and reloading the page.
Removed the function once I reloaded the page a few times.
Found the corresponding data in the database, which was in the wp_options table. I just searched the name of that same hook that caused the problem, and found that the option value field contained 9.5MB of text in it! Obviously the cause of the massive slowdown, since this 9.5MB of text needed to be loaded and parsed every time someone visited the page. I removed this completely from the database.
Once this was done, I started to notice incremental increases in performance on my Wordpress site over about a half hour or so. I also did another test to see if the log files were accumulating, and they were now only fluctuating between 3-4Kb, which was way better.
I hope this helps. Even though this seems to be a fairly common problem, I don't see many detailed solutions for it, so let this be the first.
Thanks

Answer 2

I believe there was an issue where if the server would go into an infinite loop if you didn't have the wp_cron.php file, since returning the error calls the file again. It's worth checking for in this case.
It's also possible that a variant might be happening - you try to access a file from wp-cron, and the file isn't found.
Even if all the files were copied, their paths might not have been copied correctly.

Answer 3

The cron jobs of Wordpress were causing a high CPU consumption on the server. Even defining define ('DISABLE_WP_CRON', 'true'); does not work. Without using a plugin the way I found it was to include this in the theme's functions.php:
global $wpdb;
$wpdb->update("wp_options", array("option_value"=>""), array("option_name"=>"cron"));