Overdue scheduled tasks and object cache

Hi, recently I helped a couple of WP users dealing with scheduled tasks not being executed even if the wp-cron.php was triggered enough often.
I discovered that disabling the object cache solves the problem completely (Litespeed with memcache and Aruba speed cache).

I was able to debug by modifying the wp-cron.php and found out the check at the end of the execution loop:

if ( _get_cron_lock() !== $doing_wp_cron ) {

Was ending prematurely the loop even if the “lock” was not “stolen”. Probably the object cache was returning a stale value. The second case seemed not related to the lock but to the caching of the “cron jobs”, but I was unable to debug it.

I would suggest, limited to the wp-cron.php, to totally avoid/disable the object caching. I was not able to determine if it’s a problem with the cache implementations or the WP code negatively affected by the object caching.

Take away: if your WP scheduler is not working correctly (you can check it with the very recomended WP Crontrol plugin), try to disable the Object Cache of your caching plugin, if active.