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From "ramkrishna.s.vasudevan (JIRA)" <j...@apache.org>
Subject [jira] [Created] (HBASE-17233) See if we should replace System.arrayCopy with Arrays.copyOfRange
Date Fri, 02 Dec 2016 07:29:58 GMT
ramkrishna.s.vasudevan created HBASE-17233:
----------------------------------------------

             Summary: 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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