potiuk commented on pull request #14792:
URL: https://github.com/apache/airflow/pull/14792#issuecomment-800681024
Hey @ashb - unfortunately we cannot and should not use `_del_` method. This
what I was afraid of but SchedulerJob is not an ordinrary class - this is an
SQLAlchemy managed class and (as I was afraid) __del__ will not run well for
this class because SQL Alchemy will introduce reference cycles and __del__ will
not work in this case. So far I was only suspecting this but now I am quite
sure of that, This is the warning printed by SQLAlchemy:
```
/usr/local/lib/python3.6/site-packages/sqlalchemy/orm/instrumentation.py:93
SAWarning: __del__() method on class <class
'airflow.jobs.scheduler_job.SchedulerJob'> will cause unreachable cycles and
memory leaks, as SQLAlchemy instrumentation often creates reference cycles.
Please remove this method.
```
It's difficult to argue with this. I had the same feeling when I read how
__dell__ and reference counting works and when I saw SchedulerJob being the ORM
class. But now I am 100% sure it was a bad idea.
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