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https://issues.apache.org/jira/browse/FLINK-8487?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16392682#comment-16392682
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ASF GitHub Bot commented on FLINK-8487:
---------------------------------------
Github user StephanEwen commented on the issue:
https://github.com/apache/flink/pull/5656
Looks good to me now.
+1
> State loss after multiple restart attempts
> ------------------------------------------
>
> Key: FLINK-8487
> URL: https://issues.apache.org/jira/browse/FLINK-8487
> Project: Flink
> Issue Type: Bug
> Components: State Backends, Checkpointing
> Affects Versions: 1.3.2
> Reporter: Fabian Hueske
> Assignee: Aljoscha Krettek
> Priority: Blocker
> Fix For: 1.3.3, 1.5.0, 1.4.3
>
>
> A user [reported this
> issue|https://lists.apache.org/thread.html/9dc9b719cf8449067ad01114fedb75d1beac7b4dff171acdcc24903d@%3Cuser.flink.apache.org%3E]
> on the user@f.a.o mailing list and analyzed the situation.
> Scenario:
> - A program that reads from Kafka and computes counts in a keyed 15 minute
> tumbling window. StateBackend is RocksDB and checkpointing is enabled.
> {code}
> keyBy(0)
> .timeWindow(Time.of(window_size, TimeUnit.MINUTES))
> .allowedLateness(Time.of(late_by, TimeUnit.SECONDS))
> .reduce(new ReduceFunction(), new WindowFunction())
> {code}
> - At some point HDFS went into a safe mode due to NameNode issues
> - The following exception was thrown
> {code}
> org.apache.hadoop.ipc.RemoteException(org.apache.hadoop.ipc.StandbyException):
> Operation category WRITE is not supported in state standby. Visit
> https://s.apache.org/sbnn-error
> ..................
> at
> org.apache.flink.runtime.fs.hdfs.HadoopFileSystem.mkdirs(HadoopFileSystem.java:453)
> at
> org.apache.flink.core.fs.SafetyNetWrapperFileSystem.mkdirs(SafetyNetWrapperFileSystem.java:111)
> at
> org.apache.flink.runtime.state.filesystem.FsCheckpointStreamFactory.createBasePath(FsCheckpointStreamFactory.java:132)
> {code}
> - The pipeline came back after a few restarts and checkpoint failures, after
> the HDFS issues were resolved.
> - It was evident that operator state was lost. Either it was the Kafka
> consumer that kept on advancing it's offset between a start and the next
> checkpoint failure (a minute's worth) or the the operator that had partial
> aggregates was lost.
> The user did some in-depth analysis (see [mail
> thread|https://lists.apache.org/thread.html/9dc9b719cf8449067ad01114fedb75d1beac7b4dff171acdcc24903d@%3Cuser.flink.apache.org%3E])
> and might have (according to [~aljoscha]) identified the problem.
> [~stefanrichte...@gmail.com], can you have a look at this issue and check if
> it is relevant?
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