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From "Sean Busbey (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-18847) remove unneeded synchronized block from hfilev2 warning in branch-1.2
Date Fri, 22 Sep 2017 12:56:00 GMT

    [ https://issues.apache.org/jira/browse/HBASE-18847?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16176367#comment-16176367
] 

Sean Busbey commented on HBASE-18847:
-------------------------------------

{quote}
-1	test4tests	0m 0s	The patch doesn't appear to include any new or modified tests. Please
justify why no new tests are needed for this patch. Also please list what manual steps were
performed to verify this patch.
{quote}

I'd say we don't need a test for this, since we're just changing a lock around a log message
and we don't have any framework for testing changes to logging currently.

> remove unneeded synchronized block from hfilev2 warning in branch-1.2
> ---------------------------------------------------------------------
>
>                 Key: HBASE-18847
>                 URL: https://issues.apache.org/jira/browse/HBASE-18847
>             Project: HBase
>          Issue Type: Bug
>          Components: Performance
>    Affects Versions: 1.2.0, 1.2.1, 1.2.2, 1.2.3, 1.2.4, 1.2.5, 1.2.6
>            Reporter: Rich Howarth
>            Assignee: Rich Howarth
>            Priority: Critical
>             Fix For: 1.2.7
>
>         Attachments: HBASE-18847-branch-1.2-00.patch
>
>
> The below code block starts at line 277 of HFileWriterV2.java. Class-level synchronization
in a heavily used code path has a demonstrably significant negative effect on performance.
I tested forcing a major compaction with 18 compaction threads per node; removing the synchronization
resulted in an order of magnitude performance increase, with the bottleneck then being at
the disks (where I want it to be).
> {code:java}
>     synchronized (HFileWriterV2.class) {
>       if (WARN_CELL_WITH_TAGS && getFileContext().isIncludesTags()) {
>         LOG.warn("A minimum HFile version of " + HFile.MIN_FORMAT_VERSION_WITH_TAGS
>           + " is required to support cell attributes/tags. Consider setting "
>           + HFile.FORMAT_VERSION_KEY + " accordingly.");
>         WARN_CELL_WITH_TAGS = false;
>       }
>     }
> {code}



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