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https://issues.apache.org/jira/browse/HBASE-18847?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16171767#comment-16171767
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Sean Busbey commented on HBASE-18847:
-------------------------------------
sounds good. I went ahead and added you to the contributor list and made you
the asignee here, so that you can upload patches if desired. If you haven't got
the time just let me know and I'll get something up.
> Huge performance bottleneck in HFileWriterV2 in 1.2.6
> -----------------------------------------------------
>
> Key: HBASE-18847
> URL: https://issues.apache.org/jira/browse/HBASE-18847
> Project: HBase
> Issue Type: Improvement
> 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
>
>
> 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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