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https://issues.apache.org/jira/browse/HBASE-9208?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13741529#comment-13741529
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Dave Latham commented on HBASE-9208:
------------------------------------
Meant to add that the patch also updates ReplicationLogCleaner to use the new
batching method to only load the ZK replication queues once per batch rather
than for every file.
> ReplicationLogCleaner slow at large scale
> -----------------------------------------
>
> Key: HBASE-9208
> URL: https://issues.apache.org/jira/browse/HBASE-9208
> Project: HBase
> Issue Type: Improvement
> Reporter: Dave Latham
> Assignee: Dave Latham
> Fix For: 0.94.12, 0.96.0
>
> Attachments: HBASE-9208.patch
>
>
> At a large scale the ReplicationLogCleaner fails to clean up .oldlogs as fast
> as the cluster is producing them. For each old HLog file that has been
> replicated and should be deleted the ReplicationLogCleaner checks every
> replication queue in ZooKeeper before removing it. This means that as a
> cluster scales up the number of files to delete scales as well as the time to
> delete each file so the cleanup chore scales quadratically. In our case it
> reached the point where the oldlogs were growing faster than they were being
> cleaned up.
> We're now running with a patch that allows the ReplicationLogCleaner to
> refresh its list of files in the replication queues from ZooKeeper just once
> for each batch of files the CleanerChore wants to evaluate.
> I'd propose updating FileCleanerDelegate to take a List<FileStatus> rather
> than a single one at a time. This would allow file cleaners that check an
> external resource for references such as ZooKeeper (for
> ReplicationLogCleaner) or HDFS (for SnapshotLogCleaner which looks like it
> may also have similar trouble at scale) to load those references once per
> batch rather than for every log.
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