I don't personally have experience with the Python SDK, so am not immediately in a position to comment on how feasible it would be to introduce a similar change there. I'll plan to write up two separate issues for adding exception handling in the Java and Python SDKs.
On Wed, Oct 3, 2018 at 12:17 PM Thomas Weise <[email protected]> wrote: > +1 for the proposal as well as the suggestion to offer it in other SDKs, > where applicable > > On Wed, Oct 3, 2018 at 8:58 AM Chamikara Jayalath <[email protected]> > wrote: > >> Sounds like a very good addition. I'd say this can be a single PR since >> changes are related. Please open a JIRA for tracking. >> >> Have you though about introducing a similar change to Python SDK ? >> (doesn't have to be the same PR). >> >> - Cham >> >> On Wed, Oct 3, 2018 at 8:31 AM Jeff Klukas <[email protected]> wrote: >> >>> If this looks good for MapElements, I agree that it makes sense to >>> extend to FlatMapElements and Filter and to keep the API consistent between >>> them. >>> >>> Do you have suggestions on how to submit changes with that wider scope? >>> Would one PR altering MapElements, FlatMapElements, Filter, ParseJsons, and >>> AsJsons be too large to reasonably review? Should I open an overall JIRA >>> ticket to track and break this into smaller PRs? >>> >>> On Wed, Oct 3, 2018 at 10:31 AM Reuven Lax <[email protected]> wrote: >>> >>>> Sounds cool. Why not support this on other transforms as well? >>>> (FlatMapElements, Filter, etc.) >>>> >>>> Reuven >>>> >>>> On Tue, Oct 2, 2018 at 4:49 PM Jeff Klukas <[email protected]> wrote: >>>> >>>>> I've seen a few Beam users mention the need to handle errors in their >>>>> transforms by using a try/catch and routing to different outputs based on >>>>> whether an exception was thrown. This was particularly nicely written up >>>>> in >>>>> a post by Vallery Lancey: >>>>> >>>>> >>>>> https://medium.com/@vallerylancey/error-handling-elements-in-apache-beam-pipelines-fffdea91af2a >>>>> >>>>> I'd love to see this pattern better supported directly in the Beam >>>>> API, because it currently requires the user to implement a full DoFn even >>>>> for the simplest cases. >>>>> >>>>> I propose we support for a MapElements-like transform that allows the >>>>> user to specify a set of exceptions to catch and route to a failure >>>>> output. >>>>> Something like: >>>>> >>>>> MapElements >>>>> .via(myFunctionThatThrows) >>>>> .withSuccessTag(successTag) >>>>> .withFailureTag(failureTag, JsonParsingException.class) >>>>> >>>>> which would output a PCollectionTuple with both the successful >>>>> outcomes of the map operation and also a collection of the inputs that >>>>> threw JsonParsingException. >>>>> >>>>> To make this more concrete, I put together a proof of concept PR: >>>>> https://github.com/apache/beam/pull/6518 I'd appreciate feedback >>>>> about whether this seems like a worthwhile addition and a feasible >>>>> approach. >>>>> >>>>
