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https://issues.apache.org/jira/browse/HBASE-17233?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15722548#comment-15722548
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ChiaPing Tsai commented on HBASE-17233:
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Thanks for your code.
The copyOfRangeInternal() creates the new array every time, but the
arrayCopyInternal() uses the array(res) which is created only once.
Does it cause the big diff?
> 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
>
> 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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