[jira] [Commented] (AIRFLOW-4311) LocalExecutor sleeps unnecessary after executing tasks

["ASF GitHub Bot (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/AIRFLOW-4311?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16817332#comment-16817332 ] 

ASF GitHub Bot commented on AIRFLOW-4311:
-----------------------------------------

BasPH commented on pull request #5096: [AIRFLOW-4311] Remove sleep in LocalExecutor
URL: https://github.com/apache/airflow/pull/5096
 
 
   The LocalExecutor currently sleeps after running a task. This is unnecessary and the time could be used more efficiently for running the next task. I wrote a performance test (not added in code, see below) which ran a set of dummy tasks much faster as the executor doesn't sleep in between tasks. (with parallelism=2, 1000 dummy tasks completed in 8 seconds vs 505 seconds)
   
   I'm confused about the reason behind the sleeps. The [very first Airflow commit](https://github.com/apache/airflow/commit/1047940ca4363b04044c4963b9c88f7632746407#diff-16ea362a3d5cc3987eb854ccb7f129c9R88) added them, I'm guessing for debugging, and it hasn't been looked at ever since.
   
   ### Jira
   
   - [x] My PR addresses the following [Airflow Jira](https://issues.apache.org/jira/browse/AIRFLOW/) issues and references them in the PR title. For example, "\[AIRFLOW-XXX\] My Airflow PR"
     - https://issues.apache.org/jira/browse/AIRFLOW-4311
     - In case you are fixing a typo in the documentation you can prepend your commit with \[AIRFLOW-XXX\], code changes always need a Jira issue.
     - In case you are proposing a fundamental code change, you need to create an Airflow Improvement Proposal ([AIP](https://cwiki.apache.org/confluence/display/AIRFLOW/Airflow+Improvements+Proposals)).
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   ### Description
   
   - [x] Here are some details about my PR, including screenshots of any UI changes:
   
   ### Tests
   
   - [x] My PR adds the following unit tests __OR__ does not need testing for this extremely good reason:
   
   I did not add tests, however wrote one for testing the performance with and without changes:
   
   ```python
   def test_performance(self):
       executor = LocalExecutor(parallelism=2)
       executor.start()
   
       for i in range(1000):
           key, command = "test_{0}".format(i), ["true", "testing..."]
           executor.execute_async(key=key, command=command)
           executor.running[key] = True
   
       executor.end()
   ```
   
   ### Commits
   
   - [x] My commits all reference Jira issues in their subject lines, and I have squashed multiple commits if they address the same issue. In addition, my commits follow the guidelines from "[How to write a good git commit message](http://chris.beams.io/posts/git-commit/)":
     1. Subject is separated from body by a blank line
     1. Subject is limited to 50 characters (not including Jira issue reference)
     1. Subject does not end with a period
     1. Subject uses the imperative mood ("add", not "adding")
     1. Body wraps at 72 characters
     1. Body explains "what" and "why", not "how"
   
   ### Documentation
   
   - [x] In case of new functionality, my PR adds documentation that describes how to use it.
     - All the public functions and the classes in the PR contain docstrings that explain what it does
     - If you implement backwards incompatible changes, please leave a note in the [Updating.md](https://github.com/apache/airflow/blob/master/UPDATING.md) so we can assign it to a appropriate release
   
   ### Code Quality
   
   - [x] Passes `flake8`
   
 
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> LocalExecutor sleeps unnecessary after executing tasks
> ------------------------------------------------------
>
>                 Key: AIRFLOW-4311
>                 URL: https://issues.apache.org/jira/browse/AIRFLOW-4311
>             Project: Apache Airflow
>          Issue Type: Improvement
>            Reporter: Bas Harenslak
>            Priority: Major
>




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