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From "ramkrishna.s.vasudevan (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-15205) Do not find the replication scope for every WAL#append()
Date Fri, 12 Feb 2016 08:58:18 GMT

    [ https://issues.apache.org/jira/browse/HBASE-15205?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15144278#comment-15144278
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ramkrishna.s.vasudevan commented on HBASE-15205:
------------------------------------------------

bq.Instead we directly set the scope that is passed over from HRegion per WALKey.
As said in earlier comments, in case of Multi Cf table and if only one or two CF has non default
replication scope, even if the WALEdit is made up of cells from the non default CF we will
still be writing the replication scope per WAL Key. 
If we really don't want this way - then I think we can enable a configuration and make it
false by default and enable the older way if the config is true.

> Do not find the replication scope for every WAL#append()
> --------------------------------------------------------
>
>                 Key: HBASE-15205
>                 URL: https://issues.apache.org/jira/browse/HBASE-15205
>             Project: HBase
>          Issue Type: Sub-task
>          Components: regionserver
>            Reporter: ramkrishna.s.vasudevan
>            Assignee: ramkrishna.s.vasudevan
>            Priority: Minor
>             Fix For: 2.0.0
>
>         Attachments: HBASE-15205.patch, HBASE-15205_1.patch, ScopeWALEdits.jpg, ScopeWALEdits_afterpatch.jpg
>
>
> After the byte[] and char[] the other top contributor for lot of GC (though it is only
2.86%) is the UTF_8.newDecoder.
> This happens because for every WAL append we try to calculate the replication scope associate
with the families associated with the TableDescriptor. I think per WAL append doing this is
very costly and creates lot of garbage. 



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