wp-cron.php header comments confused or confusing

[gbell12]

The header for wp-cron.php says:

WordPress Cron Implementation for hosts, which do not offer CRON or for which
the user has not set up a CRON job pointing to this file.

That's nonsensical, I think. It should say:

WordPress cron implementation to be called directly (e.g. via wget or curl) 
for sites which do not get enough visitors to properly trigger wp_cron in 
wp-includes/wp_cron.php

[kraftbj]

What about: WordPress cron implementation able to be called directly or called automatically when ALTERNATE_WP_CRON is defined.

Some sites will want to replace the visit-trigger method with a standard server cron (via define('DISABLE_WP_CRON', true);) so the number of visitors isn't the issue.

Thanks for the report! The current language is confusing.

[gbell12]

Must I set DISABLE_WP_CRON if I am calling wp-cron.php directly? That is, must one replace the other? What happens if both visits and curl/wget are triggering cron?

I run server crons to my sites a few times a day, just as insurance, from a centralised server that doesn't want to do it every 5 minutes. I'd prefer if visits caused wp's cron to run more frequently, which means leaving DISABLE_WP_CRON unset.

Is that OK and does that change your version of the comment?

[SergeyBiryukov]

Leaving DISABLE_WP_CRON unset should be OK, yes.

[gbell12]

Hmm - also spawn_cron in wp-includes/cron.php calls wp-cron.php.

I'm a unclear as to the division of labor between cron.wp and wp-cron.php. I'll go investigate before I suggest the next version of the comment wording.

[DrewAPicture]

@dd32 Any chance you could provide some clarity here? I can see improving the header comments, but it would be good to have a good handle on best-practice for overriding cron at the host level.

[stevenlinx]

1.)

As discussed previously, there are two different needs here:

i) Ensuring WP Cron runs at a minimum of X number of times alongside the visit-trigger method (as @gbell12 desired)

ii) Replacing WP Cron altogether

I think the comment header can be better by clarifying how the users can perform each of these two.

2.)

@gbell12

quote:

..wp_cron in wp-includes/wp_cron.php

There is no wp-includes/wp_cron.php. It's wp-includes/cron.php.

quote:

Hmm - also spawn_cron in wp-includes/cron.php calls wp-cron.php. I'm a unclear as to the division of labor between cron.wp and wp-cron.php....

This is basically what each does:

/wp-includes/cron.php => contains the entire WordPress Cron API and the functions needed to schedule WP Cron tasks. This is more for internal calling (e.g. by plugins).

/wp-cron.php => performs the actual action of looping through each of the WP Cron tasks and executing them.

3.)
I've uploaded a patch.

[DrewAPicture]

In 41276:

Docs: Improve the usefulness and accuracy of the file header for wp-cron.php.

Props stevenlinx for the initial patch.
Fixes #31401.