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https://issues.apache.org/jira/browse/HBASE-9208?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13745252#comment-13745252
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Dave Latham commented on HBASE-9208:
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{quote}For the 0.94 patch, why is this needed:{quote}
That is there because the ReplicationLogCleaner no longer implements
isLogDeletable and instead implements getDeletableFiles directly. This brings
up a good point that I had not carefully considered. What are the
compatibility requirements for log cleaners? The current patches break
compatibility and would require existing log cleaners to implement the changed
interface or extend the BaseFileCleanerDelegate. This seems like a bad idea
for 0.94, but probably ok for 0.96. What's the best alternative?
Perhaps rather than changing FileCleanerDelegate we could introduce a new
interface BatchFileCleanerDelegate or some such. Then configured cleaners that
implement that interface can use it but others could still work by wrapping
them. Anyone agree with that approach or have other suggestions?
> ReplicationLogCleaner slow at large scale
> -----------------------------------------
>
> Key: HBASE-9208
> URL: https://issues.apache.org/jira/browse/HBASE-9208
> Project: HBase
> Issue Type: Improvement
> Components: Replication
> Reporter: Dave Latham
> Assignee: Dave Latham
> Fix For: 0.94.12, 0.96.0
>
> Attachments: HBASE-9208-0.94.patch, HBASE-9208.patch,
> HBASE-9208-v2.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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