[wp-hackers] Bad data in getting into the "cron" row in my wp_*_options tables

[dave morris]

I have about 2000 blogs running on a WP 3.0.1 install, and we get
roughly 15-20 million pageviews a month across all the blogs. We rely
on wp-cron to do normal things like publish scheduled posts, delete
old items from the trash, etc... We also use wp-cron to schedule other
events, like the wp-super-cache garbage collection mechanism, and a
custom page view counter plugin that we wrote.

I'm noticing that on a number of our higher traffic blogs, we are
getting a ton of duplicate data in the "cron" row in our blog options
tables. For example, here is a piece of the serialized array in one of
our blogs:

"wp_update_themes";a:1:{s:32:"40cd750bba9870f18aada2478b24840a";a:3:{s:
8:"schedule";s:10:"twicedaily";s:4:"args";a:0:{}s:8:"interval";i:
43200;}}}i:1307720204;a:3:{s:16:"wp_version_check";a:1:{s:
32:"40cd750bba9870f18aada2478b24840a";a:3:{s:8:"schedule";s:
10:"twicedaily";s:4:"args";a:0:{}s:8:"interval";i:43200;}}s:
17:"wp_update_plugins";a:1:{s:32:"40cd750bba9870f18aada2478b24840a";a:
3:{s:8:"schedule";s:10:"twicedaily";s:4:"args";a:0:{}s:8:"interval";i:
43200;}}s:16:"wp_update_themes";a:1:{s:
32:"40cd750bba9870f18aada2478b24840a";a:3:{s:8:"schedule";s:
10:"twicedaily";s:4:"args";a:0:{}s:8:"interval";i:43200;}}}i:
1307720525;a:3:{s:17:"wp_update_plugins";a:1:{s:
32:"40cd750bba9870f18aada2478b24840a";a:3:{s:8:"schedule";s:
10:"twicedaily";s:4:"args";a:0:{}s:8:"interval";i:43200;}}s:
16:"wp_update_themes";a:1:{s:32:"40cd750bba9870f18aada2478b24840a";a:3:
{s:8:"schedule";s:10:"twicedaily";s:4:"args";a:0:{}s:8:"interval";i:
43200;}}s:16:"wp_version_check";a:1:{s:
32:"40cd750bba9870f18aada2478b24840a";a:3:{s:8:"schedule";s:
10:"twicedaily";s:4:"args";a:0:{}s:8:"interval";i:43200;}}}i:
1307720754;a:3:{s:16:"wp_version_check";a:1:{s:
32:"40cd750bba9870f18aada2478b24840a";a:3:{s:8:"schedule";s:
10:"twicedaily";s:4:"args";a:0:{}s:8:"interval";i:43200;}}s:
17:"wp_update_plugins";a:1:{s:32:"40cd750bba9870f18aada2478b24840a";a:
3:{s:8:"schedule";s:10:"twicedaily";s:4:"args";a:0:{}s:8:"interval";i:
43200;}}s:16:"wp_update_themes";a:1:{s:
32:"40cd750bba9870f18aada2478b24840a";a:3:{s:8:"schedule";s:
10:"twicedaily";s:4:"args";a:0:{}s:8:"interval";i:43200;}}}i:
1307721110;a:3:{s:16:"wp_version_check";a:1:{s:
32:"40cd750bba9870f18aada2478b24840a";a:3:{s:8:"schedule";s:
10:"twicedaily";s:4:"args";a:0:{}s:8:"interval";i:43200;}}s:
17:"wp_update_plugins";a:1:{s:32:"40cd750bba9870f18aada2478b24840a";a:
3:{s:8:"schedule";s:10:"twicedaily";s:4:"args";a:0:{}s:8:"interval";i:
43200;}}s:16:"wp_update_themes";a:1:{s:
32:"40cd750bba9870f18aada2478b24840a"

Notice that wp_version_check and other entries appear multiple times.
Is this the expected behavior? It seems to be causing a ton of extra
load to be placed on our servers, and I'm wondering how I can go about
fixing the issue.

I have heard that simply deleting this row from the table periodically
could help, but that doesn't seem like a good long term solution.

Thanks for your help,
Dave