airflow-commits mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Vishal Doshi (JIRA)" <>
Subject [jira] [Commented] (AIRFLOW-62) XCom push not working reliably
Date Wed, 31 Aug 2016 20:59:20 GMT


Vishal Doshi commented on AIRFLOW-62:

I'm getting this error as well. It's intermittent. When I look at the logs, it looks like
the TaskInstance is being run twice, and when run is called the second time, `self.clear_xcom_data()`
is called before the system realizes the run previously succeeded.

Not sure why it's run twice.

>From my log:

[2016-08-31 17:59:16,221] {} INFO - Filling up the DagBag from /dags/
[2016-08-31 17:59:17,451] {} INFO - Sparse computation disabled.
[2016-08-31 17:59:18,528] {} INFO - Map reduce machinery disabled.
[2016-08-31 17:59:20,969] {} INFO - Filling up the DagBag from /dags/
[2016-08-31 17:59:22,632] {} INFO - Sparse computation disabled.
[2016-08-31 17:59:23,759] {} INFO - Map reduce machinery disabled.
[2016-08-31 17:59:25,617] {} INFO - Filling up the DagBag from /dags/
[2016-08-31 17:59:26,365] {} INFO - 
Starting attempt 1 of 1

[2016-08-31 17:59:26,395] {} INFO - Executing <Task(PythonOperator): myoperator>
on 2016-08-31 17:58:28
[2016-08-31 17:59:27,781] {} INFO - Sparse computation disabled.
[2016-08-31 17:59:28,443] {} INFO - Done. Returned value was: None
[2016-08-31 17:59:28,912] {} INFO - Map reduce machinery disabled.
[2016-08-31 17:59:33,337] {} INFO - Filling up the DagBag from /dags/
[2016-08-31 17:59:35,571] {} INFO - Sparse computation disabled.
[2016-08-31 17:59:36,669] {} INFO - Map reduce machinery disabled.
[2016-08-31 17:59:37,915] {} INFO - Task <TaskInstance: compute.myoperator
2016-08-31 17:58:28 [success]> previously succeeded on 2016-08-31 17:59:28


> XCom push not working reliably
> ------------------------------
>                 Key: AIRFLOW-62
>                 URL:
>             Project: Apache Airflow
>          Issue Type: Bug
>          Components: celery
>    Affects Versions: Airflow 1.7.0
>         Environment: Postgres backed Airflow running with Celery inside of the puckel
Docker setup.
>            Reporter: Alex Papanicolaou
>            Assignee: Jeremiah Lowin
>             Fix For: Airflow 1.7.0
> I have a DAG that polls for activity in various data streams from a database and then
uploads the activity statuses to a table.  Each of the polling tasks are python operators
that once they get the polling result, return a dict as an XCom push.  The dict contains two
entries which are strings, one which is a bool, and one which is a datetime object.  There
is a final task that pulls all the results and uploads the collective statuses to a table.
 I chose this pattern since I figured it might be better to do one collective write operation
on all the results.
> Before I moved ahead to the github master branch I was using 1.7.0 from PyPI and this
worked fine.  Now that I am on the github master branch, I find that the XCom pushing is unreliable.
 The returned values in the logs show up correctly but when doing the XCom pull, I get None
for some of the returned values.  Investigating the XCom result in the Webserver also shows
nothing there.  But if I rerun a task where the XCom failed, the push works and the XCom result
is as it should be.
> Nothing appears to have changed in the codebase so I am at a loss.  Perhaps it really
wasn't working before?  How would the backing postgres handle these simultaneous writes? 
I can't imagine that would be a problem.

This message was sent by Atlassian JIRA

View raw message