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  1. Apache Airflow
  2. AIRFLOW-6912

Airflow unable to run concurrent ssh tasks (up to 27) in a single dag

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    • Type: Bug
    • Status: Open
    • Priority: Major
    • Resolution: Unresolved
    • Affects Version/s: 1.10.9
    • Fix Version/s: None
    • Component/s: executors, scheduler
    • Labels:
    • Environment:
      Kubernetes 1.13


      Current working Airflow version: 1.10.7

      Environment: Kubernetes 1.13, Helm chart 5.2.4

      Airflow version that breaks: 1.10.9


      • We have a list of ssh_operators tasks in a dag that need to be executed in parallel (as shown in the screenshot) and everything is working fine at Airflow version 1.10.7
      • We tried to update Airflow to version 1.10.9 and the tasks break in random orders and number. (as shown in the screenshot)
      • Here are some of the error that we collected:
        • (psycopg2.OperationalError) FATAL: ¬†remaining connection slots are reserved for non-replication superuser connections
        • Executor reports task instance <TaskInstance: <dag_name>.<task_name> 2020-02-20 12:20:00+00:00 [queued]> finished (failed) although the task says its queued. Was the task killed externally?
        • <TaskInstance: <dag_name>.<task_name> 2020-02-20 08:20:00+00:00 [running]> detected as zombie
        • (psycopg2.OperationalError) FATAL: remaining connection slots are reserved for non-replication superuser connections

      Actions taken:

      • We suspected that there were not enough database connections so we increased the¬†AIRFLOWCORESQL_ALCHEMY_POOL_SIZE value from 5 to 50 but the problem still persists.
      • We reverted the version back to 1.10.7 and everything works as per normal.




            • Assignee:
              Unassigned Assign to me
              phuc Nguyen Lam Phuc


              • Created:

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