[wp-trac] [WordPress Trac] #36470: Multisite - network sites list not very memory efficient

[WordPress Trac]

#36470: Multisite - network sites list not very memory efficient
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 Reporter:  Bombdogs        |      Owner:
     Type:  defect (bug)    |     Status:  new
 Priority:  normal          |  Milestone:  Awaiting Review
Component:  Administration  |    Version:  4.3
 Severity:  normal          |   Keywords:
  Focuses:                  |
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 This recent change in 4.3 to add user counts to multisite network admin
 sites list can cause out of memory errors on installs with many thousands
 of users...

 https://core.trac.wordpress.org/attachment/ticket/32434/32434.2.patch

 On a vanilla WPMU install with 200,000 users (bulk generated by wp-cli)
 the wp-admin memory footprint for the network admin sites list page can be
 as low as 32Mb when running WP4.2 - simply upgrading to WP4.3 requires you
 to increase this to 128Mb (~4x) for this size user base. The memory
 requirement keeps increasing as the user base increases (unsustainable).

 The problem in the code referenced in the patch above is that all users
 for a blog are selected out of the DB and then a count is done in PHP -
 this requires more memory than is ideal - selecting just the count will be
 quicker and more memory efficient.

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Ticket URL: <https://core.trac.wordpress.org/ticket/36470>
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