o-nikolas opened a new pull request, #30361: URL: https://github.com/apache/airflow/pull/30361
### Overview This PR aims to improve the time it takes to load/import the various executor modules we have in Airflow. ### Motivation The executors are imported in more places now that various compatibility checks are in core Airflow code (re: AIP-51). Also, decreasing import times is very important for the work of executors vending CLI commands (see #29055), since the CLI code in Airflow is particularly sensitive to slow imports (because all code is loaded fresh each time you run an individual Airflow CLI command). ### The changes This PR mostly includes changes to move some expensive imports that are only used for type checking under the `TYPE_CHECKING` flag so that they are not run at runtime. The most important changes are in the `BaseExecutor` module since all other executors load this module, and so benefits made here propagate outward. ### Testing I benchmarked these changes by writing a script to import the various executor modules in a fresh python runtime and timing how long that takes (you can test this yourself quickly from a bash shell by doing something like `time python -c 'from airflow.executors.local_executor import LocalExecutor'`). Then doing that in a loop for several samples (with some randomness in the order for fairness) both on main and on my development branch. ### Results  Most executors saw a ~50% speed increase. Kubernetes, and to a lesser extent Celery, are still quite slow and will need more changes specifically targeted to those modules (in a future PR). The combined executors (e.g. LocalKubernetesExecutor) saw less gains since they import two executors each, so they're paying double the cost (so they saw half the gains, 25%) <!-- Thank you for contributing! Please make sure that your code changes are covered with tests. And in case of new features or big changes remember to adjust the documentation. Feel free to ping committers for the review! In case of an existing issue, reference it using one of the following: closes: #ISSUE related: #ISSUE How to write a good git commit message: http://chris.beams.io/posts/git-commit/ --> --- **^ Add meaningful description above** Read the **[Pull Request Guidelines](https://github.com/apache/airflow/blob/main/CONTRIBUTING.rst#pull-request-guidelines)** for more information. In case of fundamental code changes, an Airflow Improvement Proposal ([AIP](https://cwiki.apache.org/confluence/display/AIRFLOW/Airflow+Improvement+Proposals)) is needed. In case of a new dependency, check compliance with the [ASF 3rd Party License Policy](https://www.apache.org/legal/resolved.html#category-x). In case of backwards incompatible changes please leave a note in a newsfragment file, named `{pr_number}.significant.rst` or `{issue_number}.significant.rst`, in [newsfragments](https://github.com/apache/airflow/tree/main/newsfragments). -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
