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Posted to issues@spark.apache.org by "Apache Spark (Jira)" <ji...@apache.org> on 2020/09/30 03:43:00 UTC
[jira] [Assigned] (SPARK-33022) partition length is wrong after
merge partition segments in BypassMergeSortShuffleWriter
[ https://issues.apache.org/jira/browse/SPARK-33022?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Apache Spark reassigned SPARK-33022:
------------------------------------
Assignee: Apache Spark
> partition length is wrong after merge partition segments in BypassMergeSortShuffleWriter
> ----------------------------------------------------------------------------------------
>
> Key: SPARK-33022
> URL: https://issues.apache.org/jira/browse/SPARK-33022
> Project: Spark
> Issue Type: Bug
> Components: Spark Core
> Affects Versions: 2.4.6
> Reporter: duanmeng
> Assignee: Apache Spark
> Priority: Major
>
> The segment file may be empty even after writer committing caused by disk/kernel in heavy load cluster. Compare segment length with copied length to guard it.
> A data file might be empty even after DiskBlockObjectWriter committing it in BypassMergeSortShuffleWriter, returned wrong lengths in writePartitionedFile used by MapStatus, and then cause data lost.
> This is related to disk/kernel but we can avoid it in spark without any performance loss. We can compare partitionWriterSegments[i].length with the length[i] after Utils.copyStream.
> I added some logs and reproduce the issue,
> The log when this issue happened
> {code:java}
> 20/09/28 00:42:44 INFO sort.BypassMergeSortShuffleWriter: partitionWriterSegments[0]: (name=temp_shuffle_38244ef5-8e97-4428-97b8-feffc16fc9f7, offset=0, length=1462)
> 20/09/28 00:42:46 INFO sort.BypassMergeSortShuffleWriter: File length: 0
> 20/09/28 00:42:46 INFO sort.BypassMergeSortShuffleWriter: Copied stream length: 0{code}
>
> The peer log when this issue didn't happen
> {code:java}
> 20/09/28 10:11:45 INFO sort.BypassMergeSortShuffleWriter: partitionWriterSegments[0]: (name=temp_shuffle_f6937469-39fd-4576-b40e-69f4276cc8e4, offset=0, length=1462)
> 20/09/28 10:11:45 INFO sort.BypassMergeSortShuffleWriter: File length: 1462
> 20/09/28 10:11:45 INFO sort.BypassMergeSortShuffleWriter: Copied stream length: 1462
> {code}
>
>
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