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https://issues.apache.org/jira/browse/HIVE-13429?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Daniel Dai updated HIVE-13429:
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Attachment: HIVE-13429.2.patch
> 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
> Attachments: HIVE-13429.1.patch, HIVE-13429.2.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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