https://github.com/apache/airflow/pull/12139 added some new params to the scheduler -- we have "cursory" docs for them in the comments in the config file, but we should have a more details docs in the scheduler.rst page.
airflow/jobs/scheduler_job.py
**skip_locked(session=session),
        ).all()
        
        
        if len(task_instances_to_examine) == 0:
            self.log.debug("No tasks to consider for execution.")
            return executable_tis
        
        task_instance_str = "\n\t".join([repr(x) for x in task_instances_to_examine])
        self.log.info("%s tasks up for execution:\n\t%s", len(task_instances_to_examine), task_instance_str)
        pool_to_task_instances: DefaultDict[str, List[models.Pool]] = defaultdict(list)
        for task_instance in task_instances_to_examine:
            pool_to_task_instances[task_instance.pool].append(task_instance)
        
        dag_concurrency_map: DefaultDict[str, int]
        task_concurrency_map: DefaultDict[Tuple[str, str], int]
        dag_concurrency_map, task_concurrency_map = self.__get_concurrency_maps(
            states=list(EXECUTION_STATES), session=session
        )
        num_tasks_in_executor = 0
        
        num_starving_tasks_total = 0
        
        
        
        for pool, task_instances in pool_to_task_instances.items():
            pool_name = pool
            if pool not in pools:
                self.log.warning("Tasks using non-existent pool '%s' will not be scheduled", pool)
                continue