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From "Anoop Sam John (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-15203) Reduce garbage created by path.toString() during Checksum verification
Date Tue, 02 Feb 2016 07:31:40 GMT

    [ https://issues.apache.org/jira/browse/HBASE-15203?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15127826#comment-15127826
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Anoop Sam John commented on HBASE-15203:
----------------------------------------

{code}
this.path = path;
1373	      this.pathName = path.toString();
{code}
Looks like we don't need both as instance members.  Can change path type to String than Path.
 All usage of this doing a toString (directly or indirectly)

> Reduce garbage created by path.toString() during Checksum verification
> ----------------------------------------------------------------------
>
>                 Key: HBASE-15203
>                 URL: https://issues.apache.org/jira/browse/HBASE-15203
>             Project: HBase
>          Issue Type: Sub-task
>          Components: regionserver
>            Reporter: ramkrishna.s.vasudevan
>            Assignee: ramkrishna.s.vasudevan
>            Priority: Minor
>             Fix For: 2.0.0
>
>         Attachments: HBASE-15203.patch
>
>
> When we try to read a block we do checksum verification for which we need the file name
in which the block belongs to. So we do Path.toString() every time. This seems to create around
163MB of char[] that is garbage collected in a simple scan run. It is also visible in writes
but the impact is lesser. In overall write/read profile the top 2 factors are byte[] and char[].
This toString() can easily be avoided and reduce its share from the total. To make it more
precise in 1 min of profiling, among the 1.8G of garbage created by StringBuilder.toString
- this path.toString() was contributing around 3.5%. After the patch this is totally not there.




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