wdp_un_updates_data database entry is causing 502 error by overflowing Wordpress' autoload

I am having trouble with multiple WPMU DEV plugins that are adding a ton of info to the autoload from the database. The db entry wdp_un_updates_data has over 300kb of data (my server times out at 500kb) and I'm not really sure what is causing all the information overload. How do I reduce the amount of data and queries being caused by the plugins (most notably CoursePress Pro) in order to eliminate these 502 errors?

For reference, here is some of the data showing up under the database entry for wdp_un_updates_data:

a:14:{s:8:"projects";a:176:{i:1003656;a:22:{s:2:"id";i:1003656;s:4:"paid";s:4:"paid";s:4:"type";s:6:"plugin";s:4:"name";s:16:"Membership 2 Pro";s:8:"released";i:1433432625;s:7:"updated";i:1435915221;s:9:"downloads";s:4:"6769";s:10:"popularity";s:4:"2491";s:17:"short_description";s:92:"The most powerful, easy-to-use and flexible membership plugin for WordPress sites available.";s:7:"version";s:7:"1.0.0.8";s:10:"autoupdate";s:1:"1";s:9:"changelog";s:970:"<p>- Add new option to customize which users are considered Admin users (details in the Help > Advanced page)
- Fix a typo in the PayPal Single gateway that caused M2 to ignore some payment information
- Fix bugs that prevented removing protection from individual posts or pages
- Fix the search function on the Members page
- Fix two possible infinite loops that resulted in timeouts or rule values not being saved
- Fix wrong protection logic of the Admin Side Add-on
- Fix wrong protection logic of the Advanced Menu Add-on
- Fix small issue that did not correctly disable the Media Add-on
- Fix a wrong parameters that limited search results of list tables to 5 items in some cases
- Fix the description text of the ms-protected-content shortcode for admin users
- Fix a typo in the ms_rule_has_access filter
- Fix a possible/rare mis-configuration that could happen on single-site installations</p>
";s:10:"compatible";s:50:"WordPress 4.2.2, Multisite 4.2.2, BuddyPress 2.3.2";s:8:"requires";s:2:"wp";s:3:"url";s:47:"https://premium.wpmudev.org/project/membership/";s:9:"thumbnail";s:82:"https://premium.wpmudev.org/wp-content/uploads/2014/10/Product-Content-280x158.png";s:16:"instructions_url";s:53:"https://premium.wpmudev.org/project/membership/#usage";s:11:"support_url";s:56:"https://premium.wpmudev.org/forums/tags/membership-2-pro/";s:13:"wp_config_url";s:26:"admin.php?page=membership2";s:13:"ms_config_url";s:0:"";s:7:"package";i:0;s:11:"screenshots";a:4:{i:0;a:2:

That goes on for thousands of lines. Your help is much appreciated.

Thanks,
Paul

  • Michael Bissett

    Hey @Paul, hope you're doing well this evening! :slight_smile:

    The wdp_un_updates_data row gets created by our WPMU DEV Dashboard plugin, and is necessary for it's operation, I'm not seeing that there's really anything about that row that can be tweaked.

    I've got several test sites that run fine with this row present though, and I'm curious as to the 502 error you're seeing... could you elaborate as to how you narrowed it down to this particular database row in your troubleshooting?

    What shows up in your server's error log regarding the 502 errors you've been seeing?

    Please advise,
    Michael

  • Brenda

    Hey Michael,

    I submitted a support request with my hosting provider at wpengine. In trying to solve the 502 errors users were intermittently getting on my site (primarily when accessing courses from coursepress) I was told this by my provider:

    Thanks for your patience! I've taken a look and it appears that the amount of autoloaded data may be playing a part in your site's slowness.

    Autoloaded data includes information that's necessary to generate a site's page. For example, the Home and Siteurl variables are needed in different places when the site's domain name is referenced. When the cumulative amount of autoloaded data goes above 500KB, slowness and 502s can be experienced. At this time, your site is using 670KB of autoloaded data.

    Here's a breakdown of the top ten rows storing this data:

    wdp_un_updates_data 307960
    woothemes-sensei-upgrades 77512
    rewrite_rules 30534
    wordpress-https_secure_external_urls 30531
    woo_template 25481
    _site_transient_available_translations 20816
    wp_hsnvei_user_roles 18539
    jetpack_file_data 16778
    wpmudev-chat-banned 14761
    wdp_un_profile_data 13944
    Clearing out the data tied to wdp_un_updates_data should help to speed things up.

    As far as the database queries that are being generated by the site, there are 182 queries created for an uncached request of the /courses page. The majority of those queries are tied to the coursepress and wordpress-https plugins.

    I deleted as many of those entries as I could (including remnants of a sensei and woocommerce installation) and it has increased the speed of the site, however I'm not sure whether the 502 errors are gone for good (they are intermittent and usually appear when more than one student is accessing the site at once).

    I'm guessing db queries play a big role too. There are more queries from courserpress than all other aspects of my site combined (83 total according to wpengine). I understand it's a resource-intensive plugin, but is there any way to mitigate some of this in order to avoid the errors?

    It looks like the error logs for my server have been emptied, but one support person from wpengine said the following:

    the majority of all the 502's are coming from the /active-courses/ or /courses/olc40-ontario-secondary-school-literacy/

    since they are logging in, it is still part of the wp-admin, which is an uncached area of the site. The logs are showing that the pages are just loaded down and being killed by out server timeout scripts

    My guess is that if students are logging in at the same time, since the environment is uncached, they are loading down the server with the timeouts, and getting 502's

    Maybe there's something else going on here that we're overlooking? I've opened support access to my site in case someone could take a look at what's happening on the backend.

    Thanks for your help,
    Paul

  • Brenda

    Hi,

    Just an update, I have narrowed down the issue. For some reason, certain student accounts get a 502 when attempting to log into the site only when the "Redirect after login" option is turned on in the CoursePress settings. It only happens for some users, but it happens predictably every time. I have wracked my brain trying to see why it happens for some students and not others, there seems to be no difference between users. I have disabled all other plugins and I still get the issue.

    It's not necessarily a redirect issue, for some reason about 8 users get an error as soon as the access anything coursepress-related, like their active courses, dashboard, unit material, etc. New students do not encounter the same issue. It makes me wonder if there's something similar to this going on: https://premium.wpmudev.org/forums/topic/coursepress-getting-fatal-errors-on-nearly-every-page

    Your guidance is appreciated,

    Paul

  • Brenda

    I'm finding a ton of support entries with seemingly the same problem as I:

    https://premium.wpmudev.org/forums/topic/coursepress-update-causes-user-login-issue
    https://premium.wpmudev.org/forums/topic/we-are-experiencing-extremely-slow-sites-when-working-with

    All of these have a response from one of your staff saying to try this beta version found here: https://premium.wpmudev.org/forums/topic/coursepress-pro-user-cant-login#post-884453

    But that link is no longer active. Any update on this and what's causing the issue? My site is essentially unusable without this.

    Best,
    Paul

  • Michael Bissett

    Hey @Paul, my apologies for the delay here!

    I've got a more recent version that you can try out on your site, here's what you'll want to do:

    This are the steps to follow:
    - Create a snapshot/backup of your DB. (we've got our Snapshot Pro plugin available)
    - Install the new version attached to this thread by overwriting the old plugin folder via FTP.
    - Have the affected students log out from your site, clear their browser cookies & cache, and try to reproduce the issues that they've been running into.

    You can download the RC here:

    https://www.dropbox.com/s/4rgryshqig7n1k5/coursepress_1.2.5.9-rc20150710.zip

    If any issues come up, please let me know! :slight_smile:

    Kind Regards,
    Michael

  • Chris

    Hi I'm having the same issue with wdp_un_updates_data and I use wpengine too...

    I'm confused, I dont use any course plugins or anything like this, I use only custom sidebars, wpsmush.., what is it thats causing this exactly?

    Is it the WPMU Dev plugin? i'm limited on my technical capacity, please advise.

    Can I drop the wdp_un_updates_data table from phpmyadmin?
    What data is this table storing?