Github user kl0u commented on the issue:
https://github.com/apache/flink/pull/5811
Well it seems like for these tests, the `flush` is not actually flushing.
The files are there, the `validPartLength` is correct (=6 as we just write
`test1\n`) but the data is not actually on disk. If you call `close()` on the
in-progress file when snapshotting, then the tests succeed and the data is
there.
I would recommend to just remove the check for now, and open a followup
JIRA that contains the check that you will remove, and also points on the
discussion about HDFS not flushing, and we see how to proceed.
I thing that the fact that the end-to-end tests pass point to the direction
that sth is wrong with the FS abstraction.
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