Thanks Alexey! I understand. Continue thinking in possible solutions of committing records, I was thinking about what happens in this scenario:
When processing windows of data, do they get processed in sequential order or is it possible for them to be processed out of order? For example Window 1 contains 10000 elements of data whereas window 2 contains 10 elements. Assuming Window 1 takes a while to process all of that data, is it possible window 2 will finish before window 1? Thanks again! On Fri, 10 Dec 2021 at 14:39, Alexey Romanenko <[email protected]> wrote: > I answered the similar questions on SO a while ago [1], and I hope it will > help. > > “By default, pipeline.apply(KafkaIO.read()...) will return > a PCollection<KafkaRecord<K, V>>. So, downstream in your pipeline you can > get an offset from KafkaRecord metadata and commit it manually in a way > that you need (just don't forget to disable AUTO_COMMIT in KafkaIO.read()). > > By manual way, I mean that you should instantiate your own Kafka client in > your DoFn, process input element (as KafkaRecord<K, V>), that was read > before, fetch an offset from KafkaRecord and commit it with your own > client. > > Though, you need to make sure that a call to external API and offset > commit will be atomic to prevent potential data loss (if it's critical)." > > [1] > https://stackoverflow.com/questions/69272461/how-to-manually-commit-kafka-offset-in-apache-beam-at-the-end-of-specific-dofun/69272880#69272880 > > — > Alexey > > On 10 Dec 2021, at 10:40, Juan Calvo Ferrándiz < > [email protected]> wrote: > > Thanks Luke for your quick response. I see, that makes sense. Now I have > two new questions if I may: > a) How I can get the offsets I want to commit. My investigation now is > going throw getCheckpointMark(), is this correct? > https://beam.apache.org/releases/javadoc/2.25.0/org/apache/beam/sdk/io/UnboundedSource.UnboundedReader.html#:~:text=has%20been%20called.-,getCheckpointMark,-public%20abstract%C2%A0UnboundedSource > > b) With these offsets, I will create a client at the of the pipeline, with > Kafka library, and methods such as commitSync() and commitAsync(). Is this > correct? > https://www.oreilly.com/library/view/kafka-the-definitive/9781491936153/ch04.html#:~:text=log%20an%20error.-,Asynchronous%20Commit,-One%20drawback%20of > > Thanks!!! > > *Juan * > > > On Fri, 10 Dec 2021 at 01:07, Luke Cwik <[email protected]> wrote: > >> commitOffsetsInFinalize is about committing the offset after the output >> has been durably persisted for the bundle containing the Kafka Read. The >> bundle represents a unit of work over a subgraph of the pipeline. You will >> want to ensure the commitOffsetsInFinalize is disabled and that the Kafka >> consumer config doesn't auto commit automatically. This will ensure that >> KafkaIO.Read doesn't commit the offsets. Then it is upto your PTransform to >> perform the committing. >> >> On Thu, Dec 9, 2021 at 3:36 PM Juan Calvo Ferrándiz < >> [email protected]> wrote: >> >>> Morning! >>> >>> First of all, thanks for all the incredible work you do, is amazing. >>> Then, secondly, I reach you for some help or guidance to manually commit >>> records. I want to do this so I can commit the record and the end of the >>> pipeline, and not in the read() of the KafkaIO. >>> >>> Bearing in mind what I have read in this post: >>> https://lists.apache.org/[email protected]:2021-9:[email protected]%20kafka%20commit >>> , and thinking of a pipeline similar to the one described, I understand we >>> can use commitOffsetsInFinalize() to commit offsets in the read(). What >>> I don't understand is how this helps to commit the offset if we want to do >>> this at the end, not in the reading. Thanks. All comments and >>> suggestions are more than welcome. :) >>> >>> >>> *Juan * >>> >>> >>> >
