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/models/test_taskinstance.py
task_b = PythonOperator(task_id='B', python_callable=python_callable)
                task_c = PythonOperator(task_id='C', python_callable=python_callable)
                if 'D' in init_state:
                    task_d = PythonOperator(task_id='D', python_callable=python_callable)
                for upstream, downstream in dependencies.items():
                    dag.set_dependency(upstream, downstream)
            scheduler = SchedulerJob(subdir=os.devnull)
            scheduler.dagbag.bag_dag(dag, root_dag=dag)
            dag_run = dag.create_dagrun(run_id='test_dagrun_fast_follow', state=State.RUNNING)
            task_instance_a = dag_run.get_task_instance(task_id=task_a.task_id)
            task_instance_a.task = task_a
            task_instance_a.set_state(init_state['A'])
            task_instance_b = dag_run.get_task_instance(task_id=task_b.task_id)
            task_instance_b.task = task_b
            task_instance_b.set_state(init_state['B'])
            task_instance_c = dag_run.get_task_instance(task_id=task_c.task_id)
            task_instance_c.task = task_c
            task_instance_c.set_state(init_state['C'])
            if 'D' in init_state:
                task_instance_d = dag_run.get_task_instance(task_id=task_d.task_id)
                task_instance_d.task = task_d
                task_instance_d.state = init_state['D']
            session.commit()
            task_instance_a.run()
            self.validate_ti_states(dag_run, first_run_state, error_message)
            if second_run_state:
                scheduler._critical_section_execute_task_instances(session=session)
                task_instance_b.run()
                self.validate_ti_states(dag_run, second_run_state, error_message)
    def test_set_state_up_for_retry(self):