Why is error_log not being called during my cron? - wordpress

Question

I'm trying to schedule that runs every five minutes.
The code below successfully schedules the cron, and it shows up in WP Crontrol, but "Doing a cron!" never appears in the error log.
What's going wrong?
add_action('do_cron_stuff_event', 'do_cron_stuff', 10, 2);
function do_cron_stuff()
{
error_log('Doing a cron!');
}
add_filter('cron_schedules', 'cron_stuff_add_5_minute_cron_interval');
function cron_stuff_add_5_minute_cron_interval($schedules)
{
error_log("cron_stuff_add_5_minute_cron_interval called");
$schedules['five_minutes'] =
[
'interval' => 300,
'display' => esc_html__('Every Five Minutes')
];
return $schedules;
}
register_activation_hook(__FILE__, 'cron_stuff_plugin_activation');
function cron_stuff_plugin_activation()
{
error_log("cron_stuff_plugin_activation called");
if (wp_next_scheduled('do_cron_stuff_event') === false)
{
wp_schedule_event(time(), 'five_minutes', 'do_cron_stuff_event');
}
}
register_deactivation_hook(__FILE__, 'cron_stuff_plugin_deactivation');
function cron_stuff_plugin_deactivation()
{
error_log("cron_stuff_plugin_deactivation called");
wp_clear_scheduled_hook('do_cron_stuff_event');
}

Answer 1

It turns out that error_log actually was being called, but because it was activated by a system cron, the error log output was being sent to a different error log file than the usual one.
To fix it, I used the error_log function's third parameter to send the output to a custom log file.

Answer 2

I think the problem is that you're specifying 2 $accepted_args for
add_action('do_cron_stuff_event', 'do_cron_stuff', 10, 2);
while do_cron_stuff accepts none.
Change it to
add_action('do_cron_stuff_event', 'do_cron_stuff', 10);
and see if that works.

Answer 3

WP-Cron works by: on every page load, a list of scheduled tasks is checked to see what needs to be run. Any tasks scheduled to be run will be run during that page load. WP-Cron does not run constantly as the system cron does; it is only triggered on page load. Scheduling errors could occur if you schedule a task for 2:00PM and no page loads occur until 5:00PM.
https://developer.wordpress.org/plugins/cron/
This means that you should trigger(query) /wp-cron.php from outside every 5 minutes.