public function execute() {
        global $CFG, $DB;

        $sql = "SELECT w.*
                  FROM {workshopallocation_scheduled} a
                  JOIN {workshop} w ON a.workshopid = w.id
                 WHERE a.enabled = 1
                   AND w.phase = 20
                   AND w.submissionend > 0
                   AND w.submissionend < ?
                   AND (a.timeallocated IS NULL OR a.timeallocated < w.submissionend)";
        $workshops = $DB->get_records_sql($sql, array(time()));

        if (empty($workshops)) {
            mtrace('... no workshops awaiting scheduled allocation. ', '');
            return;
        }

        mtrace('... executing scheduled allocation in ' . count($workshops) . ' workshop(s) ... ', '');

        require_once($CFG->dirroot . '/mod/workshop/locallib.php');

        foreach ($workshops as $workshop) {
            $cm = get_coursemodule_from_instance('workshop', $workshop->id, $workshop->course, false, MUST_EXIST);
            $course = $DB->get_record('course', ['id' => $cm->course], '*', MUST_EXIST);
            $workshop = new \workshop($workshop, $cm, $course);
            $allocator = $workshop->allocator_instance('scheduled');
            $allocator->execute();
        }
    }