[GitHub] [airflow] vitaly-krugl edited a comment on issue #12348: faq.rst provides incorrect instructions for reducing scheduling latency

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vitaly-krugl edited a comment on issue #12348:
URL: https://github.com/apache/airflow/issues/12348#issuecomment-727083189


   @ashb - The reason I was looking at `scheduler_heartbeat_sec` is that I am trying to improve the performance of system-level tests in my airflow-based app. 
   
   What I am seeing is that even under very low utilization, Airflow adds latency of 4-5 seconds for executing each task. I was looking at airflow.cfg options to tune to eliminate this 4-5 second per task latency on my testing setup. I haven't been able to find any combination of options that would reduce the latency below 4-5 seconds.
   
   **Any suggestions about how to eliminate these latencies?**
   
   My test setup: one DAG with two tasks: Task A and Task B, with `A >> B` relationship. Implementation is in python. Each one of the python callbacks does minimum (almost no-op) work that shows up in the logs at < 1 sec. However, each dagrun takes upwards of 9 seconds and I observe from the timestamps (dagrun, Task A start/end and Task B start/end) that there are 3-5 second gaps between dagrun and Task A start, as well as between Task A end and Task B start.


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