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https://issues.apache.org/jira/browse/HBASE-15205?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15144302#comment-15144302
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ramkrishna.s.vasudevan commented on HBASE-15205:
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bq.. It is configurable with hbase.online.schema.update.enable by default it is
true which means we do not enable and disable the table by default on alter
table command. Irrespective of that on alter table command the HRegion
constructor will be called and map will be updated accordingly.
Thanks for this info. Then we are definitely safe here.
> 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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