amoghrajesh commented on code in PR #72100:
URL: https://github.com/apache/airflow/pull/72100#discussion_r3987712204
##########
airflow-ctl/src/airflowctl/api/datamodels/generated.py:
##########
@@ -300,6 +300,13 @@ class ClearTaskInstancesBody(BaseModel):
),
] = None
prevent_running_task: Annotated[bool | None, Field(title="Prevent Running
Task")] = False
+ keep_task_state: Annotated[
Review Comment:
Handled in 218fe26b4e
##########
airflow-core/src/airflow/ui/src/pages/TaskInstances/BulkClearTaskInstancesButton.tsx:
##########
@@ -42,6 +42,7 @@ const BulkClearTaskInstancesButton = ({ clearSelections,
selectedTaskInstances }
const { onClose, onOpen, open } = useDisclosure();
const [selectedOptions, setSelectedOptions] =
useState<Array<string>>(["downstream"]);
const [note, setNote] = useState<string | null>(null);
+ const [keepTaskState, setKeepTaskState] = useState(false);
Review Comment:
Handled in 218fe26b4e
##########
airflow-core/src/airflow/ui/src/components/Clear/TaskInstance/ClearGroupTaskInstanceDialog.tsx:
##########
@@ -67,6 +67,7 @@ export const ClearGroupTaskInstanceDialog = ({ onClose, open,
taskInstance }: Pr
const future = selectedOptions.includes("future");
const upstream = selectedOptions.includes("upstream");
const downstream = selectedOptions.includes("downstream");
+ const [keepTaskState, setKeepTaskState] = useState(false);
Review Comment:
Handled in 218fe26b4e
##########
airflow-core/docs/core-concepts/resumable-tasks.rst:
##########
@@ -145,26 +145,42 @@ existing job on retry instead of submitting a new one.
For more details and a working example, see
:class:`~airflow.sdk.ResumableJobMixin`.
-**Clearing a task is treated the same as a retry**
-
-Clearing a task instance does not delete its ``task_state_store`` rows -- they
are only removed
-when the ``dag_run`` itself is deleted, or by :ref:`airflow state-store clean
-<task-and-asset-state-store-cleanup>`. For a checkpointed task this is usually
what you want:
-clearing resumes from the last checkpoint rather than starting over.
-
-For an operator with durable execution, it means clearing a task whose
external job already
-succeeded reads that stored result back and returns immediately, without
resubmitting the job. If
-you want clearing to always resubmit regardless of a prior success, set
-``[state_store] clear_on_success = True``, which deletes a task's state store
rows automatically
-when it moves to ``SUCCESS`` (see
:doc:`/administration-and-deployment/task-and-asset-state-store`).
-
-This does not guarantee the external job is still there to reconnect to,
though. Clearing a task
-that is actively running (``deferrable=False``) stops the worker process,
which runs the
-operator's ``on_kill``. Most operators with durable execution cancel the
external job there by
-default, so the next attempt finds it already stopped instead of still running
-- an operator that
-leaves the job running by default on kill is the exception, check its own
docs. Deferred tasks
-(``deferrable=True``) don't have this problem: there is no actively polling
worker process for the
-clear to interrupt.
+**Retries resume, clearing starts over**
+
+A retry keeps the task's ``task_state_store`` entries, which is what makes
crash recovery work: the
+next attempt reads the checkpoint or the external job id written by the
attempt before it.
+
+Clearing a task discards them. Clearing means "run this again", and a
checkpoint records how far a
+task got, not what it got there with. If you fixed the code or the upstream
data and cleared the
+task, resuming would leave the work done before the fix in place and silently
mix it with the
+corrected work. So by default a cleared task starts from the beginning.
+
+To resume from the checkpoint instead, set ``keep_task_state`` when clearing,
or tick the
+corresponding box in the clear dialog. That is the right choice when nothing
about the inputs or the
+code changed and you only want the task to carry on where it stopped.
+
+**Clearing a task that submitted an external job**
+
+For an operator with durable execution the stored value is an external job id,
so discarding it has
+a different consequence: the next attempt submits a new job rather than
reconnecting to the existing
+one.
+
+Whether that matters depends on what happened to the job:
+
+* Most operators cancel the external job in ``on_kill``, so clearing a
*running* task stops the job
+ and there is nothing left to reconnect to. Submitting a fresh one is the
only option anyway.
+* An operator configured to leave the job running on kill (for example
+ ``KubernetesPodOperator`` with ``on_kill_action="keep_pod"``) keeps it
alive, so a fresh submission
+ runs alongside it. Check the operator's own docs.
Review Comment:
Handled in 218fe26b4e
##########
airflow-core/src/airflow/api_fastapi/core_api/routes/public/task_instances.py:
##########
@@ -986,6 +987,10 @@ def _collect_relatives(run_id: str, direction:
Literal["upstream", "downstream"]
except AirflowClearRunningTaskException as e:
raise HTTPException(status.HTTP_409_CONFLICT, str(e)) from e
+ # After the clear has succeeded, so a failed clear cannot take the
task state with it.
+ if not body.keep_task_state:
+ _discard_task_state_store(task_instances, session,
event="Discarded task state on clear")
Review Comment:
Handled in 218fe26b4e
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