Github user shixiaogang commented on the issue:
https://github.com/apache/flink/pull/3359
Very sorry for the delay. I was engaged at the work in the past months,
making flink capable of the terrible data flows in Singles Day.
RocksDBInternalTimerService is among the improvements done.
But we adopt a very different implementation since the initial
implementation presented here has several problems:
* The initial implementation requires other rocksdb instances than the one
used in RocksDBKeyedStateBackend, which makes the resource configuration very
difficult.
* The snapshotting of RocksDBInternalTimerService here is very inefficient.
Though an asynchronous and incremental implementation is available, it will
duplicate much code in RocksDBKeyedStateBackend.
We address these problem by introducing `SecondaryKeyedState`s which
provide non-keyed access methods to the data inside a key group. Similar to
normal keyed state, secondary keyed states are partitioned in to key groups and
are also stored in the backends. Hence these secondary states can also benefit
from asynchronous and incremental snapshotting in `RocksDBKeyedStateBackend`.
What do you think of the changes ? @StefanRRichter
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