[GitHub] [airflow] ephraimbuddy commented on pull request #26518: Fix deadlock when mapped task with removed upstream is rerun

[GitBox <gi...@apache.org>]

ephraimbuddy commented on PR #26518:
URL: https://github.com/apache/airflow/pull/26518#issuecomment-1253322489

   Here's how you can reproduce this bug in main:
   Run the below dag
   Reduce the range to 3
   Then clear it to rerun and you will see it deadlock:
   
   ```python
   
   from datetime import datetime
   from airflow.decorators import dag, task
   
   @dag(
       'bug_test',
       schedule='@once',
       start_date=datetime(2022,1,1),
       max_active_runs=1
   )
   def test_scheduler_bug():
       @task
       def do_something(i):
           return 6
   
       @task
       def do_something_else(i):
           import logging
           log = logging.getLogger('airflow.task')
           log.info("I'll never run")
       # After the run, reduce this range to 2
       nums = do_something.expand(i=[i+1 for i in range(5)])
       do_something_else.expand(i=nums)
   
   TEST_DAG = test_scheduler_bug()
   ```
   
   


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