[jira] [Created] (BEAM-1850) Improve interplay between PusbackSideInputRunner and GroupAlsoByWindowViaWindowSetDoFn

["Aljoscha Krettek (JIRA)" <ji...@apache.org>]

Aljoscha Krettek created BEAM-1850:
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             Summary: Improve interplay between PusbackSideInputRunner and GroupAlsoByWindowViaWindowSetDoFn
                 Key: BEAM-1850
                 URL: https://issues.apache.org/jira/browse/BEAM-1850
             Project: Beam
          Issue Type: Improvement
          Components: runner-core, runner-flink
            Reporter: Aljoscha Krettek
            Assignee: Kenneth Knowles


This originated from a discussion on a PR: https://github.com/apache/beam/pull/2235

{{GroupAlsoByWindowViaWindowSetDoFn}}/{{GroupAlsoByWindowViaWindowSetNewDoFn}} and {{PushbackSideInputDoFnRunner}} don't work well together and we manually need to explode windows in {{FlinkStreamingTransformTranslators.ToKeyedWorkItem}} because of this:

 - {{GroupAlsoByWindowViaWindowSetDoFn}} is a {{DoFn<KeyedWorkItem<K, InputT>, KV<K, OutputT>>}} so you have to push in {{KeyedWorkItem}}. These themselves contain {{WindowedValue<InputT>}} (or timers).
 - For executing a {{DoFn}} we use a {{DoFnRunner}}. For our problem the interesting case is using a {{PushbackSideInputDoFnRunner}}. The interesting method is {{processElementInReadyWindows(WindowedValue<InputT> elem)}} where {{InputT}} is the input type of the {{DoFn}} which, for the windowing case, is {{KeyedWorkItem<K, InputT>}} (from above). The actual expanded type signature is thus {{processElementInReadyWindows(WindowedValue<KeyedWorkItem<K, InputT>> elem)}} where the keyed work items again contain {{WindowedValues}} (again, from above).
I think the {{PushbackSideInputDoFnRunner}} was not initially meant for executing {{GroupAlsoByWindowViaWindowSetDoFns}}.







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