Wordpress cron wp_schedule_single_event – action not always working

Question

I'm registering an event like:

wp_schedule_single_event( time(), 'do_custom_hook', array( $body ) );

Above that, I have added the following action:

add_action('do_custom_hook', 'process_custom_hook', 10);

function process_custom_hook($body){
    // custom code here
}

However, sometimes the process_custom_hook function fires, while other times, it simply doesn't (it fires most times, though. It's missed about 10%-20% of the time)

The event is always returning true, meaning that it must have registered.

Also, while testing, I made sure that the arguments (body) is always different.

Any reason why this may occur?

Answer 1

From the codex:

Note that scheduling an event to occur before 10 minutes after an existing event of the same name will be ignored, unless you pass unique values for $args to each scheduled event.

If your custom hook is only working some of the time, then this might be an avenue to look at. If you require the hook to be handled immediately, then it might be prudent to look at giving a hook a unique name, or passing unique values to the hook.

If you do not need your job to execute immediately, then you could look at utilising wp_next_scheduled() to determine when the job will next run, and set a job to run after the next scheduled job.

It's also worth noting that if this task is something which seems to have consistent logic behind it (as seems to be the case) - why not store the job information in to the database and run a cron job every 5-10 minutes to pick up any new jobs from the database and handle them as such? This would avoid needing to deal with the behaviour of wp_schedule_single_event().