[wp-trac] [WordPress Trac] #34132: Speed Issue in class-wp-customize-setting.php

[WordPress Trac]

#34132: Speed Issue in class-wp-customize-setting.php
--------------------------+-----------------------------
 Reporter:  wpweaver      |      Owner:
     Type:  defect (bug)  |     Status:  new
 Priority:  normal        |  Milestone:  Awaiting Review
Component:  Customize     |    Version:  4.3.1
 Severity:  normal        |   Keywords:
  Focuses:                |
--------------------------+-----------------------------
 I don't understand the whole algorithm, but class-wp-customize-setting.php
 has a SERIOUS speed issue using the final protected function
 multidimensional_replace( $root, $keys, $value ) function.

 The problem is related to the total number of options added to the
 customizer (using 'options' - I did not test using 'theme_mod'.

 As the number of options grows, the time to refresh the site page
 increases, apparently non-linearly.

 At some point, the time to process this function takes so long, the
 process will crash with a PHP execution timeout - 30 seconds on my system.
 There should be no algorithm, ever, dealing with simple arrays of settings
 on the order of 1000 or less that takes 30 seconds.

 This problem is very simple to reproduce. Create a simple Customizer
 section with multiple instances of 'checkbox' controls - for example:


 {{{
 $max_items = 600; // vary this - on my system, there is an execution
 timeout at about 600
 $transport = 'refresh';

         for ($i = 0 ; $i < $max_items; $i++) {

                 $speedtest_sections['speedtest-
 general']['options']["speedtest{$i}"] =
                 array(
                 'setting' => array(
                         'sanitize_callback' => 'absint',
                         'transport' => $transport,
                         ),
                 'control' => array(
                         'label' => "speedtest Control #{$i}",
                         'type'  => 'checkbox',
                         )
                 );
         }
 }}}


 As you change the number of controls generated, the refresh takes longer
 and longer and longer.

 This problem affects ALL themes using the customizer. For themes with
 maybe 50 or fewer options, the issues is tolerable, although there is a
 noticible delay. For themes with more, the delay for the user gets to be a
 real problem. And for themes like mine (Weaver Xtreme 2.0, work in
 progress, but stuck with this issue), that does in fact have 600 or more
 options, this is a FATAL issue.

 There is no reason that dealing with a mere number of options on the order
 of 100's should crash the Customizer.

 Somebody needs to open their algorithm book and find faster way to  do the
 multidimensional_replace.

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Ticket URL: <https://core.trac.wordpress.org/ticket/34132>
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