alex-balikov opened a new pull request #35810:
URL: https://github.com/apache/spark/pull/35810
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### What changes were proposed in this pull request?
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As described in
[SPARK-38320](https://issues.apache.org/jira/browse/SPARK-38320), the bug is
that it is possible for (flat)MapGroupsWithState to timeout a key even if that
key received data within the same batch. This is against the documented
(flat)MapGroupsWithState contract. The problem is due to the
StateStore.iterator not reflecting StateStore changes made *after* its creation
- this is illustrated in the test this PR adds to StateStoreSuite.scala.
The fix is to *late bind* the timeoutProcessorIter timeout processing
iterator in FlatMapGroupsWithStateExec to be created *after* the input iterator
has been exhausted and the state changes applied to the StateStore.
### Why are the changes needed?
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The changes are needed to ensure the state timeout processing iterator for
(flat)MapGroupsWithState is created *after* the input is processed and the
changes are applied into the StateStore, otherwise it may not notice these
changes (the change to the key timeout timestamp being updates as part of the
input processing).
### Does this PR introduce _any_ user-facing change?
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No. Bug fix.
### How was this patch tested?
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* Added a test to StateStoreSuite.scala to illustrate the difference of
state store iterator behavior across the different implementations of state
stores. In particular the test illustrates the RocksDB state store iterator not
reflecting state store changes made after its creation.
* Added test to FlatMapGroupsWithStateSuite.scala which would fail with
unexpected state timeout if the issue was not fixed.
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