[jira] [Created] (BEAM-12075) GroupByKey doesn't seem to work with FixedWindows

["Tianzi Cai (Jira)" <ji...@apache.org>]

Tianzi Cai created BEAM-12075:
---------------------------------

             Summary: GroupByKey doesn't seem to work with FixedWindows
                 Key: BEAM-12075
                 URL: https://issues.apache.org/jira/browse/BEAM-12075
             Project: Beam
          Issue Type: Bug
          Components: extensions-java-gcp
    Affects Versions: 2.28.0
         Environment: Java 8, 
            Reporter: Tianzi Cai


After applying `FixedWindows` on a streaming source, a `GroupByKey` operation doesn't emit keyed elements in a window. 

This example without `GroupByKey` prints all the windowed elements:

 
{noformat}
pipeline
 .apply("ReadFromPubsub", PubsubIO.readStrings().fromSubscription(subscriptionPath))
 .apply(Window.into(FixedWindows.of(Duration.standardSeconds(5L))))
 .apply(WithKeys.of("bobcat"))
 .apply(MapElements.into(TypeDescriptors.nulls()).via(
 (KV<String, String> pair) -> {
 LOG.info("Key: " + pair.getKey() + "\tValue: " + pair.getValue());
 return null;
 }
 ));{noformat}
 

This example with `GroupByKey` doesn't emit anything:

 
{noformat}
pipeline
 .apply("ReadFromPubsub", PubsubIO.readStrings().fromSubscription(subscriptionPath))
 .apply(Window.into(FixedWindows.of(Duration.standardSeconds(5L))))
 .apply(WithKeys.of("bobcat"))
 .apply(GroupByKey.create())
 .apply(FlatMapElements.into(TypeDescriptors.nulls()).via(
 (KV<String, Iterable<String>> pair) -> {
 pair.getValue().forEach(message -> LOG.info("Message: " + message));
 return null;
 }
 ));{noformat}
 

 



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