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https://issues.apache.org/jira/browse/HBASE-11322?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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churro morales updated HBASE-11322:
-----------------------------------
Attachment: HBASE-11322.patch
> SnapshotHFileCleaner makes the wrong check for lastModified time thus causing
> too many cache refreshes
> ------------------------------------------------------------------------------------------------------
>
> Key: HBASE-11322
> URL: https://issues.apache.org/jira/browse/HBASE-11322
> Project: HBase
> Issue Type: Bug
> Affects Versions: 0.94.19
> Reporter: churro morales
> Assignee: churro morales
> Priority: Critical
> Attachments: HBASE-11322.patch
>
>
> In the SnapshotFileCache:
> The last modified time is done via this operation:
> {code}
> this.lastModifiedTime = Math.min(dirStatus.getModificationTime(),
> tempStatus.getModificationTime());
> {code}
> and the check to see if the snapshot directories have been modified:
> {code}
> // if the snapshot directory wasn't modified since we last check, we are done
> if (dirStatus.getModificationTime() <= lastModifiedTime &&
> tempStatus.getModificationTime() <= lastModifiedTime) {
> return;
> }
> {code}
> so if the dirStatus and tmpStatus are modified at different times, we will
> always assume they have been modified and refresh the cache.
> In our cluster, this was a huge performance hit. The cleaner chain fell
> behind, thus almost filling up dfs and our namenode heap.
> Its a simple fix, instead of Math.min we use Math.max for the lastModified, I
> believe that will be correct.
> I'll apply a patch for you guys.
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