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From "Hudson (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-15203) Reduce garbage created by path.toString() during Checksum verification
Date Thu, 04 Feb 2016 11:59:39 GMT

    [ https://issues.apache.org/jira/browse/HBASE-15203?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15132217#comment-15132217
] 

Hudson commented on HBASE-15203:
--------------------------------

FAILURE: Integrated in HBase-Trunk_matrix #678 (See [https://builds.apache.org/job/HBase-Trunk_matrix/678/])
HBASE-HBASE-15203 Reduce garbage created by path.toString() during (ramkrishna: rev 2cf8af5bf1d501156cbb3b421cf75c1051ead7d9)
* hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/HFileBlock.java
* hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/ChecksumUtil.java


> 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, HBASE-15203_1.patch, HBASE-15203_2.patch, HBASE-15203_branch-1.1.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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