ashb opened a new pull request #8814: URL: https://github.com/apache/airflow/pull/8814
In debugging another test I noticed that the scheduler was spending a long time waiting for a "simple" dag to be parsed. But upon closer inspection the parsing process itself was done in a few milliseconds, but we just weren't harvesting the results in a timely fashion. This change uses the `sentinel` attribute of multiprocessing.Connection (added in Python 3.3) to be able to wait for all the processes, so that as soon as one has finished we get woken up and can immediately harvest and pass on the parsed dags. This makes test_scheduler_job.py about twice as quick, and also reduces the time the scheduler spends between tasks . In real work loads, or where there are lots of dags this likely won't equate to much such a huge speed up, but for our (synthetic) elastic performance test dag. These were the timings for the dag to run all the tasks in a single dag run to completion., with PERF_SCHEDULE_INTERVAL='1d' PERF_DAGS_COUNT=1 I also have PERF_SHAPE=linear PERF_TASKS_COUNT=12: **Before**: 45.4166s **After**: 16.9499s PERF_SHAPE=linear PERF_TASKS_COUNT=24: **Before**: 82.6426s **After**: 34.0672s PERF_SHAPE=binary_tree PERF_TASKS_COUNT=24: **Before**: 20.3802s **After**: 9.1400s PERF_SHAPE=grid PERF_TASKS_COUNT=24: **Before**: 27.4735s **After**: 11.5607s If you have many more dag **files**, this likely won't be your bottleneck. --- Make sure to mark the boxes below before creating PR: [x] - [x] Description above provides context of the change - [x] Unit tests coverage for changes (not needed for documentation changes) - [x] Target Github ISSUE in description if exists - [x] Commits follow "[How to write a good git commit message](http://chris.beams.io/posts/git-commit/)" - [x] Relevant documentation is updated including usage instructions. - [x] I will engage committers as explained in [Contribution Workflow Example](https://github.com/apache/airflow/blob/master/CONTRIBUTING.rst#contribution-workflow-example). --- In case of fundamental code change, Airflow Improvement Proposal ([AIP](https://cwiki.apache.org/confluence/display/AIRFLOW/Airflow+Improvements+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 [UPDATING.md](https://github.com/apache/airflow/blob/master/UPDATING.md). Read the [Pull Request Guidelines](https://github.com/apache/airflow/blob/master/CONTRIBUTING.rst#pull-request-guidelines) for more information. ---------------------------------------------------------------- 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. For queries about this service, please contact Infrastructure at: us...@infra.apache.org
