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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