We have flaky scheduler test:


https://github.com/apache/airflow/pull/11659/checks?check_run_id=1279791496#step:6:527


_______________ TestSchedulerJob.test_scheduler_task_start_date ________________

self = <tests.jobs.test_scheduler_job.TestSchedulerJob testMethod=test_scheduler_task_start_date>

    def test_scheduler_task_start_date(self):
        """
        Test that the scheduler respects task start dates that are different from DAG start dates
        """
    
        dagbag = DagBag(dag_folder=os.path.join(settings.DAGS_FOLDER, "no_dags.py"), include_examples=False)
        dag_id = 'test_task_start_date_scheduling'
        dag = self.dagbag.get_dag(dag_id)
        dag.is_paused_upon_creation = False
        dagbag.bag_dag(dag=dag, root_dag=dag)
    
        # Deactivate other dags in this file so the scheduler doesn't waste time processing them
        other_dag = self.dagbag.get_dag('test_start_date_scheduling')
        other_dag.is_paused_upon_creation = True
        dagbag.bag_dag(dag=other_dag, root_dag=other_dag)
    
        dagbag.sync_to_db()
    
        scheduler = SchedulerJob(executor=self.null_exec,
                                 subdir=dag.fileloc,
                                 num_runs=2)
        scheduler.run()
    
        session = settings.Session()
        tiq = session.query(TaskInstance).filter(TaskInstance.dag_id == dag_id)
        ti1s = tiq.filter(TaskInstance.task_id == 'dummy1').all()
        ti2s = tiq.filter(TaskInstance.task_id == 'dummy2').all()
        self.assertEqual(len(ti1s), 0)
>       self.assertEqual(len(ti2s), 2)
E       AssertionError: 1 != 2
tests/jobs/test_scheduler_job.py
dagbag = DagBag(dag_folder=ELASTIC_DAG_FILE, include_examples=False, read_dags_from_db=False)
            dagbag.sync_to_db()
            dag_ids = dagbag.dag_ids
            dagbag = DagBag(read_dags_from_db=True)
            for i, dag_id in enumerate(dag_ids):
                dag = dagbag.get_dag(dag_id)
                dr = dag.create_dagrun(
                    state=State.RUNNING,
                    run_id=f"{DagRunType.MANUAL.value}__{i}",
                    dag_hash=dagbag.dags_hash[dag.dag_id],
                )
                dagruns.append(dr)
                for ti in dr.get_task_instances():
                    ti.set_state(state=State.SCHEDULED)
            mock_agent = mock.MagicMock()
            job = SchedulerJob(subdir=PERF_DAGS_FOLDER, num_runs=1)
            job.executor = MockExecutor(do_update=False)
            job.heartbeat = mock.MagicMock()
            job.processor_agent = mock_agent
            with assert_queries_count(expected_query_count):
                with mock.patch.object(DagRun, 'next_dagruns_to_examine') as mock_dagruns:
                    mock_dagruns.return_value = dagruns
                    job._run_scheduler_loop()
    @parameterized.expand(
        [
            
            
            ([8, 8, 8, 8], 1, 1, "1d", "None", "no_structure"),  
            ([8, 8, 8, 8], 1, 1, "1d", "None", "linear"),  
            ([20, 11, 11, 11], 1, 1, "1d", "@once", "no_structure"),