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
"""Sends SLA Callbacks to DagFileProcessor if tasks have SLAs set and check_slas=True"""
        if not settings.CHECK_SLAS:
            return
        if not any(isinstance(ti.sla, timedelta) for ti in dag.tasks):
            self.log.debug("Skipping SLA check for %s because no tasks in DAG have SLAs", dag)
            return
        if not self.processor_agent:
            raise ValueError("Processor agent is not started.")
        self.processor_agent.send_sla_callback_request_to_execute(
            full_filepath=dag.fileloc, dag_id=dag.dag_id
        )
    @provide_session
    def _emit_pool_metrics(self, session: Session = None) -> None:
        pools = models.Pool.slots_stats(session=session)
        for pool_name, slot_stats in pools.items():
            Stats.gauge(f'pool.open_slots.{pool_name}', slot_stats["open"])
            Stats.gauge(f'pool.queued_slots.{pool_name}', slot_stats[State.QUEUED])
            Stats.gauge(f'pool.running_slots.{pool_name}', slot_stats[State.RUNNING])
    @provide_session
    def heartbeat_callback(self, session: Session = None) -> None:
        Stats.incr('scheduler_heartbeat', 1, 1)
    @provide_session
    def adopt_or_reset_orphaned_tasks(self, session: Session = None):