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From "churro morales (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-11360) SnapshotFileCache refresh logic based on modified directory time might be insufficient
Date Wed, 18 Jun 2014 22:30:26 GMT

    [ https://issues.apache.org/jira/browse/HBASE-11360?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14036553#comment-14036553
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churro morales commented on HBASE-11360:
----------------------------------------

What happens if you are taking a snapshot that takes a long time enough for 3 cleaner runs

The first run of the cleaner sees the directory is modified (updates partially its files)

Second run sees nothing has modified deletes archive files

Snapshot finishes ".finished" file is written

Third run starts, sees the ".finished" file updates its cache but its too late as some files
have already been removed while the snapshot was still in progress.



> SnapshotFileCache refresh logic based on modified directory time might be insufficient
> --------------------------------------------------------------------------------------
>
>                 Key: HBASE-11360
>                 URL: https://issues.apache.org/jira/browse/HBASE-11360
>             Project: HBase
>          Issue Type: Bug
>    Affects Versions: 0.94.19
>            Reporter: churro morales
>
> Right now we decide whether to refresh the cache based on the lastModified timestamp
of all the snapshots and those "running" snapshots which is located in the /hbase/.hbase-snapshot/.tmp/<snapshot>
directory
> We ran a ExportSnapshot job which takes around 7 minutes between creating the directory
and copying all the files. 
> Thus the modified time for the 
> /hbase/.hbase-snapshot/.tmp directory was 7 minutes earlier than the modified time of
the
> /hbase/.hbase-snapshot/.tmp/<snapshot> directory
> Thus the cache refresh happens and doesn't pick up all the files but thinks its up to
date as the modified time of the .tmp directory never changes.
> This is a bug as when the export job starts the cache never contains the files for the
"running" snapshot and will fail.



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