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https://issues.apache.org/jira/browse/HDFS-8892?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14706455#comment-14706455
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Ravikumar commented on HDFS-8892:
---------------------------------
Iterating over all replicas is a cause of concern. Is it possible for client to
ack a slot made invalid by DN? But my guess is that, it would needlessly
complicate this issue.
May be the patch itself is applicable for specific use-cases…
How about exposing a boolean config
"dfs.client.read.shortcircuit.replica.stale.cleanup" and wrapping this small
patch in a conditional block?
> ShortCircuitCache.CacheCleaner can add Slot.isInvalid() check too
> -----------------------------------------------------------------
>
> Key: HDFS-8892
> URL: https://issues.apache.org/jira/browse/HDFS-8892
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: hdfs-client
> Affects Versions: 2.7.1
> Reporter: Ravikumar
> Assignee: kanaka kumar avvaru
> Priority: Minor
>
> Currently CacheCleaner thread checks only for cache-expiry times. It would be
> nice if it handles an invalid-slot too in an extra-pass of evictable map…
> for(ShortCircuitReplica replica:evictable.values()) {
> if(!scr.getSlot().isValid()) {
> purge(replica);
> }
> }
> //Existing code...
> int numDemoted = demoteOldEvictableMmaped(curMs);
> int numPurged = 0;
> Long evictionTimeNs = Long.valueOf(0);
> ….
> …..
> Apps like HBase can tweak the expiry/staleness/cache-size params in
> DFS-Client, so that ShortCircuitReplica will never be closed except when Slot
> is declared invalid.
> I assume slot-invalidation will happen during block-invalidation/deletes
> {Primarily triggered by compaction/shard-takeover etc..}
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