[jira] [Commented] (HBASE-17233) See if we should replace System.arrayCopy with Arrays.copyOfRange

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

    [ https://issues.apache.org/jira/browse/HBASE-17233?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16850046#comment-16850046 ] 

Biju Nair commented on HBASE-17233:
-----------------------------------

So the conclusion is {{Arrays.copyOfRange}} is better performing than {{System.arraycopy}}. Correct? By how much?

> See if we should replace System.arrayCopy with Arrays.copyOfRange
> -----------------------------------------------------------------
>
>                 Key: HBASE-17233
>                 URL: https://issues.apache.org/jira/browse/HBASE-17233
>             Project: HBase
>          Issue Type: Improvement
>    Affects Versions: 2.0.0
>            Reporter: ramkrishna.s.vasudevan
>            Assignee: ramkrishna.s.vasudevan
>            Priority: Major
>
> Just saw this interesting comment in PB code. Since we deal with byte[] extensively (when we are onheap) we do lot of copies too.
> {code}
> * <p>One of the noticeable costs of copying a byte[] into a new array using
>    * {@code System.arraycopy} is nullification of a new buffer before the copy. It has been shown
>    * the Hotspot VM is capable to intrisicfy {@code Arrays.copyOfRange} operation to avoid this
>    * expensive nullification and provide substantial performance gain. Unfortunately this does not
>    * hold on Android runtimes and could make the copy slightly slower due to additional code in
>    * the {@code Arrays.copyOfRange}. 
> {code}
> So since we are hotspot VM we could see if the places we use System.arrayCopy can be replaced with Arrays.copyOfRange.



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