Segmented state stores turn on bulk loading of the underlying RocksDB
when restoring. This is correct for segmented state stores that
are in restore mode on active tasks and the onRestoreStart() and
onRestoreEnd() in RocksDBSegmentsBatchingRestoreCallback take care
of toggling bulk loading mode on and off. However, restoreAll()
in RocksDBSegmentsBatchingRestoreCallback might also turn on bulk loading
mode. When this happens on a stand-by task bulk loading mode is never
turned off. That leads to steadily increasing open file decriptors
in RocksDB because in bulk loading mode RocksDB creates continuously new
files but never compacts them (which is the intended behaviour).
Reviewers: A. Sophie Blee-Goldman <sophie@confluent.io>, Guozhang Wang <wangguoz@gmail.com>
Bruno Cadonna