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https://issues.apache.org/jira/browse/FLINK-5715?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15902829#comment-15902829
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ASF GitHub Bot commented on FLINK-5715:
---------------------------------------
Github user StephanEwen commented on the issue:
https://github.com/apache/flink/pull/3466
I think this is all in all very good code!
One thing I am worried about is the testing time now. The
`EventTimeWindowCheckpointingITCase` tests already take super long, now we have
two more.
What we should probably do is make the following:
- The data volume is very high in that test, and I think that was mainly
done to stress RocksDB's async snapshots a bit.
- The heaviness can be moved to a RocksDB specific async snapshot test
(that does not need to use windows)
- The base of the EventTimeWindowCheckpointingITCases can then be made
much more lightweight.
> Asynchronous snapshotting for HeapKeyedStateBackend
> ---------------------------------------------------
>
> Key: FLINK-5715
> URL: https://issues.apache.org/jira/browse/FLINK-5715
> Project: Flink
> Issue Type: New Feature
> Components: State Backends, Checkpointing
> Affects Versions: 1.3.0
> Reporter: Stefan Richter
> Assignee: Stefan Richter
>
> Blocking snapshots render the HeapKeyedStateBackend practically unusable for
> many user in productions. Their jobs can not tolerate stopped processing for
> the time it takes to write gigabytes of data from memory to disk.
> Asynchronous snapshots would be a solution to this problem. The challenge for
> the implementation is coming up with a copy-on-write scheme for the in-memory
> hash maps that build the foundation of this backend. After taking a closer
> look, this problem is twofold. First, providing CoW semantics for the hashmap
> itself, as a mutible structure, thereby avoiding costly locking or blocking
> where possible. Second, CoW for the mutable value objects, e.g. through
> cloning via serializers.
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