get_users/WP_User_Query is not scalable

[duck_]

Related: #15786, #14572

Use of get_users (and by extension WP_User_Query) is not scalable for sites with a large number of users. Fatal errors occur when caching all the resulting users to memory.

Example usage which causes fatal errors in 3.1 (no fatal error in 3.0.3 for a site with even more users):

• Deleting a user (​wp-admin/users.php line 175)
• XML-RPC request for wp.getAuthors (​wp-includes/class-wp-xmlrpc-server.php line 783)
• Creating a network (​wp-admin/schema.php line 670)
• wp_list_authors (​wp-includes/author-template.php line 287)

And probably others, grep for get_users.

Patches for first to examples attached, but I can't help but feel this is just papering over the issue.

[scribu]

(In [17010]) Use wp_dropdown_users() in the delete confirmation screen. Props duck_. See #15854

[scribu]

(In [17011]) Get only required fields in wp_getAuthors(). Props duck_. See #15854

[scribu]

I guess we should add a 'cache_results' parameter to WP_User_Query and set it to false by default.

[scribu]

(In [17012]) Get only required fields in populate_network(). See #15854

[scribu]

(In [17013]) Make WP_User_Query return regular objects by default. Fixes #15854

[westi]

This change breaks backwards compat for get_users_of_blog

In 3.0 this joined on the usermeta table and returned and array of stdclass with the caps as a properties too.

It doesn't anymore after this last set of changes.

[scribu]

In 3.0 this joined on the usermeta table and returned and array of stdclass with the caps as a properties too.

More precisely, it had a 'meta_value' property, which contained the capabilities:

​http://core.trac.wordpress.org/browser/tags/3.0.3/wp-includes/user.php#L328

[scribu]

I propose we revert get_users_of_blog() to it's 3.0 state and deprecate it.

[scribu]

Deprecated get_users_of_blog()

[westi]

deprecating the function and restoring the old direct SQL is lame.

Is there no way to wrap get_users and still return the old data structure?

[scribu]

deprecating the function and restoring the old direct SQL is lame.

To that I will reply that get_users_of_blog() is lame. :)

Is there no way to wrap get_users and still return the old data structure?

Only if we loop through each result, serialize back the 'capabilities' property and add it as 'meta_value'.

[ryan]

Per IRC discussion, going with 15854.diff.

[ryan]

(In [17084]) Revert get_users_of_blog() to 3.0 behavior and deprecate. Use get_users() in core. Props scribu. fixes #15854

[nacin]

Glad things get tested before commit. [17010] was borked and wasn't caught until now. #16361