[jira] [Resolved] (HBASE-3693) isMajorCompaction() check triggers lots of listStatus DFS RPC calls from HBase

["stack (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HBASE-3693?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

stack resolved HBASE-3693.
--------------------------

      Resolution: Fixed
    Hadoop Flags: [Reviewed]

Committed to TRUNK (not to branch since only an 'improvement').  Nice patch Liyin.  Thanks.

> isMajorCompaction() check triggers lots of listStatus DFS RPC calls from HBase
> ------------------------------------------------------------------------------
>
>                 Key: HBASE-3693
>                 URL: https://issues.apache.org/jira/browse/HBASE-3693
>             Project: HBase
>          Issue Type: Improvement
>            Reporter: Kannan Muthukkaruppan
>            Assignee: Liyin Tang
>         Attachments: Hbase-3693[r1085248]_2.patch, Hbase-3693[r1085306].patch
>
>
> We noticed that there are lots of listStatus calls on the ColumnFamily directories within each region, coming from this codepath:
> {code}
> compactionSelection()
>  --> isMajorCompaction 
>     --> getLowestTimestamp()
>        -->  FileStatus[] stats = fs.listStatus(p);
> {code}
> So on every compactionSelection() we're taking this hit. While not immediately an issue, just from log inspection, this accounts for quite a large number of RPCs to namenode at the moment and seems like an unnecessary load to be sending to the namenode.
> Seems like it would be easy to cache the timestamp for each opened/created StoreFile, in memory, in the region server, and avoid going to DFS each time for this information.

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