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From "Suresh Srinivas (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HDFS-554) BlockInfo.ensureCapacity may get a speedup from System.arraycopy()
Date Thu, 27 Aug 2009 22:41:59 GMT

    [ https://issues.apache.org/jira/browse/HDFS-554?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12748603#action_12748603
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Suresh Srinivas commented on HDFS-554:
--------------------------------------

Also the array size that we are copying is generally 9 (assuming 3 replicas)

> 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
>            Priority: Minor
>
> 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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