[wp-trac] [WordPress Trac] #61188: switch_to_blog() causes Fatal error on classic themes

[WordPress Trac]

#61188: switch_to_blog() causes Fatal error on classic themes
-------------------------------+------------------------------
 Reporter:  digberlin          |       Owner:  (none)
     Type:  defect (bug)       |      Status:  new
 Priority:  normal             |   Milestone:  Awaiting Review
Component:  Themes             |     Version:  6.5.3
 Severity:  normal             |  Resolution:
 Keywords:  reporter-feedback  |     Focuses:  multisite
-------------------------------+------------------------------

Comment (by digberlin):

 Replying to [comment:1 swissspidy]:
 > Hi there and welcome to WordPress Trac!
 >
 > Can you please share some code to reproduce this issue and where exactly
 you are using this code?
 >
 > It sounds like your code is inadvertently creating some infinite loop or
 so, hence the memory issue.

 Thank you swissspidy for looking into this.

 In my themes, I switch to the main site on a multisite installation and
 get customs posts.

 But this error occurs even when just calling switch_to_blog() and nothing
 else.

 For testing, I added this

 {{{
 switch_to_blog(1);
 restore_current_blog();
 }}}

 to functions.php on a clean Twenty Twenty-One Theme running on WP 5.6.3
 with no plug-ins active. Also tested on both, local dev and live
 production installations.

 Also tested on multiple other themes with same result:
 {{{
 Fatal error: Allowed memory size of 536870912 bytes exhausted (tried to
 allocate 8388608 bytes) in [redacted]/wordpress/wp-includes/class-wpdb.php
 on line 2320
 }}}

 When switching to any other site, like

 {{{
 switch_to_blog(7);
 restore_current_blog();
 }}}

 adds an additional error

 {{{
 Fatal error: Allowed memory size of 536870912 bytes exhausted (tried to
 allocate 20480 bytes) in [redacted]/wordpress/wp-includes/class-wpdb.php
 on line 2320

 Fatal error: Allowed memory size of 536870912 bytes exhausted (tried to
 allocate 20480 bytes) in [redacted]/wordpress/wp-includes/class-wp-fatal-
 error-handler.php on line 76
 }}}


 Twenty Twenty-Four is unaffected.
 WP 6.4 is unaffected.

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Ticket URL: <https://core.trac.wordpress.org/ticket/61188#comment:2>
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