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https://issues.apache.org/jira/browse/HDFS-8892?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14718308#comment-14718308
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kanaka kumar avvaru commented on HDFS-8892:
-------------------------------------------

Hi [~Ravikumar], are you planning to update code and produce patch as per 
[~cmccabe] suggestion? If yes, feel free to assign the JIRA to you. 
Otherwise, I will create the patch.

> 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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