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https://issues.apache.org/jira/browse/HBASE-11360?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14037023#comment-14037023
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Lars Hofhansl commented on HBASE-11360:
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Or more radically: I think the mistake is that we cache snapshots in .tmp at
all. These are by definition temporary, in progress, and changing. So let's
*always* refresh those, we can list the contents of the .tmp directory without
enumerating all snapshots so that should be efficient. Like so:
# we keep a cache of all snapshots not in .tmp. To detect changes in these we
only need to take the time of the snapshots directory
# we always refresh all snapshots in .tmp, and store them in a separate set
# when we check whether a snapshot contain a file we check both.
So we only check the status of the snapshot dir and we always enumerate the
.tmp directory (which should be small'ish), so overall this should be efficient.
If we agree that that would work, I'll put up a patch. Should fix both this
issue and HBASE-11322.
> 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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