[wp-trac] [WordPress Trac] #63830: Event system breaks when an event is scheduled during processing of a queue of more than one events

[WordPress Trac]

#63830: Event system breaks when an event is scheduled during processing of a queue
of more than one events
--------------------------+-----------------------------
 Reporter:  madhazelnut   |      Owner:  (none)
     Type:  defect (bug)  |     Status:  new
 Priority:  normal        |  Milestone:  Awaiting Review
Component:  Cron API      |    Version:  6.8.2
 Severity:  normal        |   Keywords:
  Focuses:                |
--------------------------+-----------------------------
 We've had instances of events "disappearing" and traced it down to them
 not being registered in the event system when a queue of more than one
 event is being processed in parallel.

 == To Reproduce

 === Step 1

 Add the following code (in a must-use plugin, for example):

 {{{#!php
 <?php
 add_action('my_regular_task', function($param) {
     // do something meaningful
 });

 add_action('my_long_task', function() {
     echo 'Started my_long_task. Maybe request an HTTP page now?', "\n";
     for($i=0;$i<5; $i++) {
         sleep(2);
         echo "\t", 'Zzz..', "\n";
     }
     echo 'Woa. Woke up!', "\n";
 });

 add_action('init', function() {
     if (!defined('WP_CLI')) {
         // This runs when requested via HTTP
         $evt = wp_schedule_single_event(time()+1 , 'my_regular_task',
 [uniqid()], true);
         if (is_wp_error($evt)) {
             die('Could not schedule event!');   // this makes sure the
 event was indeed registered as scheduled..
         }
     }
 });
 }}}

 === Step 2

 In a WPCLI session:

 {{{#!bash
 wp cron event schedule my_long_task --0=foo
 wp cron event schedule my_long_task --0=bar
 wp cron event run --due-now
 }}}

 While the two events are being processed perform one HTTP request to any
 front end page in your browser (to schedule the regular task).

 === Step 3

 {{{#!bash
 wp cron event list
 }}}

 == Expected result

 On step 3 we see the list of events containing one instance of
 `my_regular_task`.

 == Actual result

 The event list does NOT contain `my_regular_task`.

-- 
Ticket URL: <https://core.trac.wordpress.org/ticket/63830>
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