Thank you for the clarification, Max, and thanks for the quick
turnaround, Bolke. I can confirm that your fix addresses my issue.

Chris

On Wed, Apr 19, 2017, at 07:51 AM, Bolke de Bruin wrote:
> PR is out: https://github.com/apache/incubator-airflow/pull/2247
> 
> Includes tests.
> 
> - Bolke
> 
> > On 19 Apr 2017, at 05:33, Bolke de Bruin <[email protected]> wrote:
> > 
> > Agreed. This is a bug and imho a blocker for 1.8.1. 
> > 
> > My bad: re-implementation and lack of sufficient unit tests is what is 
> > causing this. 
> > 
> > I'll have a look at this asap. 
> > 
> > Bolke. 
> > 
> > Sent from my iPhone
> > 
> >> On 19 Apr 2017, at 02:52, Maxime Beauchemin <[email protected]> 
> >> wrote:
> >> 
> >> @Chris this is not the way backfill was designed originally and to me
> >> personally I'd flag the behavior you describe as a bug.
> >> 
> >> To me, backfill should just "fill in the holes", whether the state came
> >> from a previous backfill run, or the scheduler.
> >> 
> >> `airflow backfill` was originally designed to be used in conjunction with
> >> `airflow clear` when needed and together they should allow to perform
> >> whatever "surgery" you may have to do. Clear has a lot of options (from
> >> memory) to do date range, task_id regex matching, only_failures,... and so
> >> does backfill. So first you'd issue one or more clear commands to empty the
> >> false positives and [typically] its descendants, or clearing the whole DAG
> >> if you wanted to rerun the whole thing, thus creating the void for backfill
> >> to fill in.
> >> 
> >> @committers, has that changed?
> >> 
> >> Max
> >> 
> >> On Tue, Apr 18, 2017 at 3:53 PM, Paul Zaczkiewicz <[email protected]>
> >> wrote:
> >> 
> >>> I asked a very similar question last month and got no responses. Note that
> >>> SubDags execute backfill commands in in 1.8.0. The original text of that
> >>> question is as follows:
> >>> 
> >>> I've recently upgraded to 1.8.0 and immediately encountered the hanging
> >>> SubDag issue that's been mentioned. I'm not sure the rollback from rc5 to
> >>> rc4 fixed the issue.  For now I've removed all SubDags and put their
> >>> task_instances in the main DAG.
> >>> 
> >>> Assuming this issue gets fixed, how is one supposed to recover from
> >>> failures within SubDags after the # of retries have maxed?  Previously, I
> >>> would clear the state of the offending tasks and run a backfill job.
> >>> Backfill jobs in 1.7.1 would skip successful task_instances and only run
> >>> the task_instances with cleared states. Now, backfills and SubDagOperators
> >>> clear the state of successful tasks. I'd rather not re-run a task that
> >>> already succeeded. I tried running backfills with --task_regex and
> >>> --ignore_dependencies, but that doesn't quite work either.
> >>> 
> >>> If I have t1(success) -> t2(clear) -> t3(clear) and I set --task_regex so
> >>> that it excludes t1, then t2 will run, but t3 will never run because it
> >>> doesn't wait for t2 to finish. It fails because its upstream dependency
> >>> condition is not met.
> >>> 
> >>> I like the logical grouping that SubDags provide, but I don't want all
> >>> retry all tasks even if they're successful. I can see why one would want
> >>> that behavior in some cases, but it's certainly not useful in all.
> >>> 
> >>>> On Tue, Apr 18, 2017 at 6:45 PM, Chris Fei <[email protected]> wrote:
> >>>> 
> >>>> Hi all,
> >>>> 
> >>>> 
> >>>> 
> >>>> I'm new to Airflow, and I'm looking for someone to clarify the expected
> >>>> behavior of running a backfill with regard to previously successful
> >>>> tasks. When I run a backfill on 1.8.0, tasks that were previously run
> >>>> successfully are re-run for me. Is it expected that backfills re-run all
> >>>> tasks, even those that were marked as successful? For reference, the
> >>>> command I'm running is `airflow backfill -s 2017-04-01 -e 2017-04-03
> >>>> Tutorial`.
> >>>> 
> >>>> 
> >>>> I wasn't able to find anything in the documentation to indicate either
> >>>> which way. Some brief research revealed that invoking backfill was meant
> >>>> at one point to "fill in the blanks", which I interpret to mean "only
> >>>> run tasks that were not completed successfully". On the contrary, the
> >>>> code *does* seem to explicitly set all task instances for a given DAGRun
> >>>> to SCHEDULED (see [AIRFLOW-910][1] and
> >>>> https://github.com/apache/incubator-airflow/pull/2107/files#diff-
> >>>> 54a57ccc2c8e73d12c812798bf79ccb2R1816).
> >>>> 
> >>>> 
> >>>> Apologies for such a fundamental question, just want to make sure I'm
> >>>> not missing something obvious here. Can someone clarify?
> >>>> 
> >>>> 
> >>>> Thanks,
> >>>> 
> >>>> Chris Fei
> >>>> 
> >>>> 
> >>>> Links:
> >>>> 
> >>>> 1. https://issues.apache.org/jira/browse/AIRFLOW-910
> >>>> 
> >>> 
> 

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