[wp-trac] [WordPress Trac] #58001: Lazy load user capabilities in WP_User object

[WordPress Trac]

#58001: Lazy load user capabilities in WP_User object
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 Reporter:  spacedmonkey                    |       Owner:  flixos90
     Type:  enhancement                     |      Status:  reviewing
 Priority:  normal                          |   Milestone:  6.8
Component:  Users                           |     Version:
 Severity:  normal                          |  Resolution:
 Keywords:  has-patch has-unit-tests early  |     Focuses:  multisite,
                                            |  performance
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Comment (by spacedmonkey):

 @flixos90 @joemcgill The core performance problem I want to solve here is
 this:

 In WP_Query, the update_post_author_caches function is called in the_post
 method. This is just to prime all user objects in memory, as this user
 object is used in generate_postdata, that calls get_userdata. This sets a
 global authordata that should be a WP_User object.

 On a simple site with one user, that is not really a problem. The single
 user is loaded with its user meta. But once you have a set of authors,
 from all different users, like 10 posts with 10 authors, then 10 lots of
 user meta is loaded. If you have plugins that add lots of user meta keys,
 like Woo does, then, if you are loading 10 users, with say 25 pieces of
 user meta, that is already, 250 rows of meta loading. The real problem is
 if then this is done on a multisite. If you have 10 users, with 25 pieces
 of meta ( per site ) and they are across 15 sites, that is 10 x 25 x 15,
 that is 3750 rows. Even with object caching enabled, that is a lot of data
 that is loaded.

 As far as I can see, not many plugins or themes use this global
 authordata. We could consider loading setting the authordata global, but
 creating a WP_User object without loading user meta. If you wanted to use
 the authordata global, it would still be a valid WP_User, but would not
 need the user meta. I would love to be able to remove the global
 altogether, but that would be a BC break.

 The current solution I have put forward is clever and fixes the problem
 above but the magic methods are a bit of a workaround and have some risk
 attached.

 Thoughts.

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Ticket URL: <https://core.trac.wordpress.org/ticket/58001#comment:18>
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