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https://issues.apache.org/jira/browse/HBASE-15493?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15209291#comment-15209291
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stack commented on HBASE-15493:
-------------------------------
I have changed my mind after getting off the phone call with a smart operator,
totally confused by the profusion off configs and options badly confused by our
poor namings ("Is the queue size XYZ doing the same thing as the queue size
ABC?"). Now I no longer think there are 1% who are "advanced" able to tune by
reading code and doc. I do not think there any. Lets do it 'right' or not
bother.
> Default ArrayList size may not be optimal for Mutation
> ------------------------------------------------------
>
> Key: HBASE-15493
> URL: https://issues.apache.org/jira/browse/HBASE-15493
> Project: HBase
> Issue Type: Improvement
> Components: Client, regionserver
> Affects Versions: 2.0.0
> Reporter: Vladimir Rodionov
> Assignee: Vladimir Rodionov
> Fix For: 2.0.0
>
> Attachments: HBASE-15493-v1.patch, HBASE-15493-v2.patch
>
>
> {code}
> List<Cell> getCellList(byte[] family) {
> List<Cell> list = this.familyMap.get(family);
> if (list == null) {
> list = new ArrayList<Cell>();
> }
> return list;
> }
> {code}
> Creates list of size 10, this is up to 80 bytes per column family in mutation
> object.
> Suggested:
> {code}
> List<Cell> getCellList(byte[] family) {
> List<Cell> list = this.familyMap.get(family);
> if (list == null) {
> list = new ArrayList<Cell>(CELL_LIST_INITIAL_CAPACITY);
> }
> return list;
> }
> {code}
> CELL_LIST_INITIAL_CAPACITY = 2 in the patch, this is debatable. For mutation
> where every CF has 1 cell, this gives decent reduction in memory allocation
> rate in both client and server during write workload. ~2%, not a big number,
> but as I said, already, memory optimization will include many small steps.
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