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https://issues.apache.org/jira/browse/SPARK-5142?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Hyukjin Kwon resolved SPARK-5142.
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Resolution: Incomplete
> Possibly data may be ruined in Spark Streaming's WAL mechanism.
> ---------------------------------------------------------------
>
> Key: SPARK-5142
> URL: https://issues.apache.org/jira/browse/SPARK-5142
> Project: Spark
> Issue Type: Bug
> Components: DStreams
> Affects Versions: 1.2.0
> Reporter: Saisai Shao
> Priority: Major
> Labels: bulk-closed
>
> Currently in Spark Streaming's WAL manager, data will be written into HDFS
> with multiple tries when meeting failure, because of lacking of transactional
> guarantee, previously partial-written data is not rolled back and the retried
> data will be appended to the last, this will ruin the file and make the
> WriteAheadLogReader to read data with failure.
> Firstly I think this problem is hard to fix because HDFS do not support
> truncate operation(HDFS-3107) or random write with specific offset.
> Secondly, I think if we meet such write exception, it is better not to try
> again, try again will ruin the file and make read abnormal.
> Sorry if I misunderstand anything.
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