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173 | class CancellationCleanup(LoopService):
"""
A simple loop service responsible for cancelling tasks and subflows left over from
cancelling flow runs
"""
def __init__(self, loop_seconds: Optional[float] = None, **kwargs):
super().__init__(
loop_seconds=loop_seconds
or PREFECT_API_SERVICES_CANCELLATION_CLEANUP_LOOP_SECONDS.value(),
**kwargs,
)
# query for this many runs to mark failed at once
self.batch_size = 200
@inject_db
async def run_once(self, db: PrefectDBInterface):
"""
- cancels active tasks belonging to recently cancelled flow runs
- cancels any active subflow that belongs to a cancelled flow
"""
# cancels active tasks belonging to recently cancelled flow runs
await self.clean_up_cancelled_flow_run_task_runs(db)
# cancels any active subflow run that belongs to a cancelled flow run
await self.clean_up_cancelled_subflow_runs(db)
self.logger.info("Finished cleaning up cancelled flow runs.")
async def clean_up_cancelled_flow_run_task_runs(self, db):
while True:
cancelled_flow_query = (
sa.select(orm_models.FlowRun)
.where(
orm_models.FlowRun.state_type == states.StateType.CANCELLED,
orm_models.FlowRun.end_time.is_not(None),
orm_models.FlowRun.end_time
>= (pendulum.now("UTC").subtract(days=1)),
)
.limit(self.batch_size)
)
async with db.session_context() as session:
flow_run_result = await session.execute(cancelled_flow_query)
flow_runs = flow_run_result.scalars().all()
for run in flow_runs:
await self._cancel_child_runs(db=db, flow_run=run)
# if no relevant flows were found, exit the loop
if len(flow_runs) < self.batch_size:
break
async def clean_up_cancelled_subflow_runs(self, db):
high_water_mark = UUID(int=0)
while True:
subflow_query = (
sa.select(orm_models.FlowRun)
.where(
or_(
orm_models.FlowRun.state_type == states.StateType.PENDING,
orm_models.FlowRun.state_type == states.StateType.SCHEDULED,
orm_models.FlowRun.state_type == states.StateType.RUNNING,
orm_models.FlowRun.state_type == states.StateType.PAUSED,
orm_models.FlowRun.state_type == states.StateType.CANCELLING,
orm_models.FlowRun.id > high_water_mark,
),
orm_models.FlowRun.parent_task_run_id.is_not(None),
)
.order_by(orm_models.FlowRun.id)
.limit(self.batch_size)
)
async with db.session_context() as session:
subflow_run_result = await session.execute(subflow_query)
subflow_runs = subflow_run_result.scalars().all()
for subflow_run in subflow_runs:
await self._cancel_subflow(db=db, flow_run=subflow_run)
high_water_mark = max(high_water_mark, subflow_run.id)
# if no relevant flows were found, exit the loop
if len(subflow_runs) < self.batch_size:
break
async def _cancel_child_runs(
self, db: PrefectDBInterface, flow_run: orm_models.FlowRun
) -> None:
async with db.session_context() as session:
child_task_runs = await models.task_runs.read_task_runs(
session,
flow_run_filter=filters.FlowRunFilter(id={"any_": [flow_run.id]}),
task_run_filter=filters.TaskRunFilter(
state={"type": {"any_": NON_TERMINAL_STATES}}
),
limit=100,
)
for task_run in child_task_runs:
async with db.session_context(begin_transaction=True) as session:
await models.task_runs.set_task_run_state(
session=session,
task_run_id=task_run.id,
state=states.Cancelled(
message="The parent flow run was cancelled."
),
force=True,
)
async def _cancel_subflow(
self, db: PrefectDBInterface, flow_run: orm_models.FlowRun
) -> None:
if not flow_run.parent_task_run_id:
return False
if flow_run.state.type in states.TERMINAL_STATES:
return False
async with db.session_context() as session:
parent_task_run = await models.task_runs.read_task_run(
session, task_run_id=flow_run.parent_task_run_id
)
if not parent_task_run:
# Global orchestration policy will prevent further orchestration
return False
containing_flow_run = await models.flow_runs.read_flow_run(
session, flow_run_id=parent_task_run.flow_run_id
)
if (
containing_flow_run
and containing_flow_run.state.type != states.StateType.CANCELLED
):
# Nothing to do here; the parent is not cancelled
return False
if flow_run.deployment_id:
state = states.Cancelling(message="The parent flow run was cancelled.")
else:
state = states.Cancelled(message="The parent flow run was cancelled.")
async with db.session_context(begin_transaction=True) as session:
await models.flow_runs.set_flow_run_state(
session=session,
flow_run_id=flow_run.id,
state=state,
)
|