Hi All, `BaseSensorOperator` <https://airflow.apache.org/docs/apache-airflow/stable/core-concepts/sensors.html#basesensoroperator-parameters> defaults to `timeout=None` and falls back to `[sensors] default_timeout`, whose packaged default is seven days. A sensor waiting on something that never arrives holds a worker slot for a week before failing, and the retry starts the wait again. Nothing about this warns the Dag author.
I propose that we catch this at parse time, so authors see the message the moment the Dag file loads in the Dag processor rather than after the first week burns. My proposal's quite simple: - Emit a warning at parse time when a sensor is instantiated without an explicit `timeout`. - Stay quiet when the deployment has already changed the default timeout. If they set it, assume that they have thought about it. - Give deployments a config knob to silence the warning entirely (but default to *warning them*) - Apply to every sensor mode. Seven days of reschedule or a wrongly set trigger timeout still seems broken. - Keep the message agnostic on what value to pick; focus on warning, not a suggestion. No runtime behavior change. Existing Dags keep the seven day default and see the message. I also have one question: Should we also ship the UI surface(a new `DagWarningType` so it appears on the Dags list banner) or just a Dag processor warning? (It's a question of noise vs. spread here) Once I have enough feedback here, I will proceed with a PR. Thanks & Regards, Amogh Desai
