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https://issues.apache.org/jira/browse/HIVE-13429?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15249397#comment-15249397
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Lefty Leverenz commented on HIVE-13429:
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[~sladymon] documented the *cleardanglingscratchdir* tool in Setting Up
HiveServer2, and the CLI doc has a link to it:
* [Setting Up HiveServer2 -- Scratch Directory Management |
https://cwiki.apache.org/confluence/display/Hive/Setting+Up+HiveServer2#SettingUpHiveServer2-ScratchDirectoryManagement]
** [ClearDanglingScratchDirTool |
https://cwiki.apache.org/confluence/display/Hive/Setting+Up+HiveServer2#SettingUpHiveServer2-ClearDanglingScratchDirTool]
* [Hive CLI -- Tool to Clear Dangling Scratch Directories |
https://cwiki.apache.org/confluence/display/Hive/LanguageManual+Cli#LanguageManualCli-TooltoClearDanglingScratchDirectories]
[~daijy], please review. If it's okay, we can remove the TODOC labels.
Otherwise we'll make revisions as needed.
Question about another scratchdir parameter: Is
*hive.start.cleanup.scratchdir* just for the original Hive server, or is it
also for HiveServer2? In either case, its description should be updated to
make this clear.
* [Configuration Properties -- hive.start.cleanup.scratchdir |
https://cwiki.apache.org/confluence/display/Hive/Configuration+Properties#ConfigurationProperties-hive.start.cleanup.scratchdir]
> Tool to remove dangling scratch dir
> -----------------------------------
>
> Key: HIVE-13429
> URL: https://issues.apache.org/jira/browse/HIVE-13429
> Project: Hive
> Issue Type: Improvement
> Reporter: Daniel Dai
> Assignee: Daniel Dai
> Labels: TODOC1.3, TODOC2.1
> Fix For: 1.3.0, 2.1.0
>
> Attachments: HIVE-13429.1.patch, HIVE-13429.2.patch,
> HIVE-13429.3.patch, HIVE-13429.4.patch, HIVE-13429.5.patch,
> HIVE-13429.branch-1.patch
>
>
> We have seen in some cases, user will leave the scratch dir behind, and
> eventually eat out hdfs storage. This could happen when vm restarts and leave
> no chance for Hive to run shutdown hook. This is applicable for both HiveCli
> and HiveServer2. Here we provide an external tool to clear dead scratch dir
> as needed.
> We need a way to identify which scratch dir is in use. We will rely on HDFS
> write lock for that. Here is how HDFS write lock works:
> 1. A HDFS client open HDFS file for write and only close at the time of
> shutdown
> 2. Cleanup process can try to open HDFS file for write. If the client holding
> this file is still running, we will get exception. Otherwise, we know the
> client is dead
> 3. If the HDFS client dies without closing the HDFS file, NN will reclaim the
> lease after 10 min, ie, the HDFS file hold by the dead client is writable
> again after 10 min
> So here is how we remove dangling scratch directory in Hive:
> 1. HiveCli/HiveServer2 opens a well-named lock file in scratch directory and
> only close it when we about to drop scratch directory
> 2. A command line tool cleardanglingscratchdir will check every scratch
> directory and try open the lock file for write. If it does not get exception,
> meaning the owner is dead and we can safely remove the scratch directory
> 3. The 10 min window means it is possible a HiveCli/HiveServer2 is dead but
> we still cannot reclaim the scratch directory for another 10 min. But this
> should be tolerable
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