Cool! I've left a few comments. This also makes me think whether we can implement this on ParDo as well, though that might be a bit trickier since it involves hooking into DoFnInvoker.
Reuven On Fri, Oct 5, 2018 at 10:33 AM Jeff Klukas <[email protected]> wrote: > I've posted a full PR for the Java exception handling API that's ready for > review: https://github.com/apache/beam/pull/6586 > > It implements new WithErrors nested classes on MapElements, > FlatMapElements, Filter, AsJsons, and ParseJsons. > > On Wed, Oct 3, 2018 at 7:55 PM Jeff Klukas <[email protected]> wrote: > >> Jira issues for adding exception handling in Java and Python SDKs: >> >> https://issues.apache.org/jira/browse/BEAM-5638 >> https://issues.apache.org/jira/browse/BEAM-5639 >> >> I'll plan to have a complete PR for the Java SDK put together in the next >> few days. >> >> On Wed, Oct 3, 2018 at 1:29 PM Jeff Klukas <[email protected]> wrote: >> >>> 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. >>>>>>>> >>>>>>>
