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From dan bress <danbr...@gmail.com>
Subject checkpointing a OneInputStreamOperator/AbstractStreamOperator
Date Mon, 12 Sep 2016 18:30:35 GMT
Hi Flink Devs,
   I have an operator that implements both OneInputStreamOperator
and AbstractStreamOperator, and I would like to preserve its state.

   I started by having it implement CheckpointedAsynchronously like my
other stateful functions, but this didn't work(in the flink UI under the
checkpoint tab, this function doesn't show anything, where the others do.
Is this because its a lower level operator, and not a function?).  Also
functionally, the state did not seem to be preserved in my dataflow.

   Where can I go from here?  Should I implement

StreamTaskState snapshotOperatorState(long checkpointId, long timestamp)
throws Exception;
and
void restoreState(StreamTaskState state) throws Exception;

defined in StreamOperator

   I tried doing this, but the semantics of these methods were a little
confusing, and when I implemented it I started getting null pointer
exceptions in restoreState.  Also the amount of stuff I had to do seemed
like it was more than when implementing CheckpointedAsynchronously

   Is there an example of how to implement a low level operator with
checkpointing?

Any help would be appreciated,

Thanks!

Dan

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