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From "Todd Lipcon (Commented) (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-554) BlockInfo.ensureCapacity may get a speedup from System.arraycopy()
Date Tue, 22 Nov 2011 18:46:40 GMT

    [ https://issues.apache.org/jira/browse/HDFS-554?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13155338#comment-13155338

Todd Lipcon commented on HDFS-554:

I think we want to use {{last*3}} instead of {{old.length}} here - it may be a little shorter.
> BlockInfo.ensureCapacity may get a speedup from System.arraycopy()
> ------------------------------------------------------------------
>                 Key: HDFS-554
>                 URL: https://issues.apache.org/jira/browse/HDFS-554
>             Project: Hadoop HDFS
>          Issue Type: Improvement
>          Components: name-node
>    Affects Versions: 0.21.0
>            Reporter: Steve Loughran
>            Assignee: Harsh J
>            Priority: Minor
>             Fix For: 0.24.0
>         Attachments: HDFS-554.patch
> BlockInfo.ensureCapacity() uses a for() loop to copy the old array data into the expanded
array.  {{System.arraycopy()}} is generally much faster for this, as it can do a bulk memory
copy. There is also the typesafe Java6 {{Arrays.copyOf()}} to consider, though here it offers
no tangible benefit.

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