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https://issues.apache.org/jira/browse/AIRFLOW-513?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Kevin Yuen updated AIRFLOW-513:
-------------------------------
Description:
Hi,
We are using airflow version 1.7.0 and we are using `ExternalTaskSensor` pretty
heavily to manage dependencies between our DAGs.
We have recently experienced a case where the external task sensors are causing
the DAGs to go into limbo state because they took up all the execution slots
defined via `AIRFLOW__CORE__PARALLELISM`.
For example:
Given we have 2 DAGs:
first one with 16 python operator tasks, and the other with 16 sensors. We
set `PARALLELISM` to 16.
If the scheduler choses to schedule all 16 sensors first, the dag runs will
never complete.
There are a couple of work around to this:
# staggering the DAGs so that the first dag with python operator runs first
# lowering the TaskSensor timeout thresholds and relying on retries
Both of these options seems less then ideal to us. We wonder if
`ExternalTaskSensor` should really be counting towards the `PARALLELISM` limit?
Cheers,
Kevin
was:
Hi,
We are using airflow version 1.7.0 and we are using `ExternalTaskSensor` pretty
heavily to manage dependencies between our DAGs.
We have recently experienced a case where the external task sensors are causing
the DAGs to go into limbo state because they took up all the execution slots
defined via `AIRFLOW__CORE__PARALLELISM`.
For example:
Given we have 2 DAGs:
first one with 16 python operator tasks, and the other with 16 sensors. We
set `PARALLELISM` to 16.
If the scheduler choses to schedule all 16 sensors first, the dag runs will
never complete.
There are a couple of work around to this:
# staggering the DAGs so that the first dag with python operator runs first
# lowering the TaskSensor timeout thresholds and relying on retries
Both of these options seems unideal to us and we wonder if `ExternalTaskSensor`
should really be counting towards the `PARALLELISM` limit?
Cheers,
Kevin
> ExternalTaskSensor tasks should not count towards parallelism limit
> -------------------------------------------------------------------
>
> Key: AIRFLOW-513
> URL: https://issues.apache.org/jira/browse/AIRFLOW-513
> Project: Apache Airflow
> Issue Type: Improvement
> Environment: Ubuntu 14.04
> Version 1.7.0
> Reporter: Kevin Yuen
>
> Hi,
> We are using airflow version 1.7.0 and we are using `ExternalTaskSensor`
> pretty heavily to manage dependencies between our DAGs.
> We have recently experienced a case where the external task sensors are
> causing the DAGs to go into limbo state because they took up all the
> execution slots defined via `AIRFLOW__CORE__PARALLELISM`.
> For example:
> Given we have 2 DAGs:
> first one with 16 python operator tasks, and the other with 16 sensors.
> We set `PARALLELISM` to 16.
> If the scheduler choses to schedule all 16 sensors first, the dag runs
> will never complete.
> There are a couple of work around to this:
> # staggering the DAGs so that the first dag with python operator runs first
> # lowering the TaskSensor timeout thresholds and relying on retries
> Both of these options seems less then ideal to us. We wonder if
> `ExternalTaskSensor` should really be counting towards the `PARALLELISM`
> limit?
> Cheers,
> Kevin
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