ashb commented on a change in pull request #18061:
URL: https://github.com/apache/airflow/pull/18061#discussion_r703570626
##########
File path: airflow/models/dagrun.py
##########
@@ -207,10 +207,26 @@ def next_dagruns_to_examine(
DagModel.is_paused == expression.false(),
DagModel.is_active == expression.true(),
)
- .order_by(
- nulls_first(cls.last_scheduling_decision, session=session),
- cls.execution_date,
+ )
+ if state == State.QUEUED:
Review comment:
We need a comment saying why we are doing here this behaviour here.
##########
File path: airflow/models/dagrun.py
##########
@@ -207,10 +207,26 @@ def next_dagruns_to_examine(
DagModel.is_paused == expression.false(),
DagModel.is_active == expression.true(),
)
- .order_by(
- nulls_first(cls.last_scheduling_decision, session=session),
- cls.execution_date,
+ )
+ if state == State.QUEUED:
+ stmt = (
+ session.query(DagModel, func.count(DagModel.dag_id))
+ .filter(DagModel.is_active == expression.true(),
DagModel.is_paused == expression.false())
+ .join(DagRun, DagRun.dag_id == DagModel.dag_id)
+ .filter(DagRun.state == State.RUNNING)
+ .group_by(DagModel.dag_id)
+ .all()
)
+ dag_ids = []
+ for dag_model, total_runs in stmt:
+ if total_runs >= dag_model.max_active_runs:
+ dag_ids.append(dag_model.dag_id)
+
+ query = query.filter(~cls.dag_id.in_(dag_ids))
Review comment:
This will work for small number of DAGs, but for large numbers (1000s or
tens of 1000s) this is going to put extra load on the DB by counting the
running dag runs ever time, even if we don't care about that dag
```python
running_drs = (
session.query(DagRun.dag_id,
func.count(DagRun.state).label('num_running'))
.filter(DagRun.state == DagRunState.RUNNING)
.group_by(DagRun.dag_id)
.cte('running_dag_runs')
)
query = query.outerjoin(running_drs, running_drs.c.dag_id ==
DagRun.dag_id).filter(
func.coalesce(running_drs.c.num_running, 0) <
DagModel.max_active_runs
)
```
##########
File path: tests/jobs/test_scheduler_job.py
##########
@@ -2689,6 +2689,100 @@ def
test_max_active_runs_in_a_dag_doesnt_stop_running_dagruns_in_otherdags(self,
)
assert len(session.query(DagRun).filter(DagRun.state ==
State.RUNNING).all()) == 11
+ def test_start_queued_dagruns_do_follow_execution_date_order(self,
dag_maker):
+ session = settings.Session()
+ with dag_maker('test_dag1', max_active_runs=1) as dag:
+ DummyOperator(task_id='mytask')
+ date = dag.following_schedule(DEFAULT_DATE)
+ for i in range(30):
+ dr = dag_maker.create_dagrun(
+ run_id=f'dagrun_{i}', run_type=DagRunType.SCHEDULED,
state=State.QUEUED, execution_date=date
+ )
+ date = dr.execution_date + timedelta(hours=1)
+ self.scheduler_job = SchedulerJob(subdir=os.devnull)
+ self.scheduler_job.executor = MockExecutor(do_update=False)
+ self.scheduler_job.processor_agent =
mock.MagicMock(spec=DagFileProcessorAgent)
+
+ self.scheduler_job._start_queued_dagruns(session)
+ session.flush()
+ dr = DagRun.find(run_id='dagrun_0')
+ ti = dr[0].get_task_instance(task_id='mytask', session=session)
+ ti.state = State.SUCCESS
+ session.merge(ti)
+ session.commit()
+ assert dr[0].state == State.RUNNING
+ dr[0].state = State.SUCCESS
+ session.merge(dr[0])
+ session.flush()
+ assert dr[0].state == State.SUCCESS
+ self.scheduler_job._start_queued_dagruns(session)
+ session.flush()
+ dr = DagRun.find(run_id='dagrun_1')
+ assert len(session.query(DagRun).filter(DagRun.state ==
State.RUNNING).all()) == 1
+
+ assert dr[0].state == State.RUNNING
+
+ def test_no_dagruns_would_stuck_in_running(self, dag_maker):
+ # Test that running dagruns are not stuck in running.
+ # Create one dagrun in 'running' state and 1 in 'queued' state from
one dag(max_active_runs=1)
+ # Create 16 dagruns in 'running' state and 16 in 'queued' state from
another dag
+ # Create 16 dagruns in 'running' state and 16 in 'queued' state from
yet another dag
+ # Finish the task of the first dag, and check that another dagrun
starts running
+ # from the first dag.
+
+ session = settings.Session()
+ with dag_maker('test_dagrun_states_are_correct_1', max_active_runs=1)
as dag:
+ task1 = DummyOperator(task_id='dummy_task')
+ dr1_running = dag_maker.create_dagrun(run_id='dr1_run_1')
Review comment:
What date is this dagrun created for? Since it matters for this text
it's better to be explicit it specify an execution_date here.
##########
File path:
airflow/migrations/versions/092435bf5d12_add_max_active_runs_column_to_dagmodel_.py
##########
@@ -0,0 +1,44 @@
+#
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements. See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership. The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License. You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied. See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+"""Add max_active_runs column to dagmodel table
+
+Revision ID: 092435bf5d12
+Revises: 142555e44c17
+Create Date: 2021-09-06 21:29:24.728923
+
+"""
+
+import sqlalchemy as sa
+from alembic import op
+
+# revision identifiers, used by Alembic.
+revision = '092435bf5d12'
+down_revision = '142555e44c17'
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+ """Apply Add max_active_runs column to dagmodel table"""
+ op.add_column('dag', sa.Column('max_active_runs', sa.Integer(),
nullable=False))
Review comment:
Fails on a DB with anything in it with this error:
```
sqlalchemy.exc.IntegrityError: (psycopg2.errors.NotNullViolation) column
"max_active_runs" of relation "dag" contains null values
```
So either we need to give it a value (0, what ever teh default is), get the
"right" value out of the serialized dag model, or allow nulls.
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