[HBASE-18847] Remove unneeded synchronized block from hfilev2 warning in branch-1.2

• Type: Bug
• Status: Resolved
• Priority: Critical
• Resolution: Fixed
• Affects Version/s: 1.2.0, 1.2.1, 1.2.2, 1.2.3, 1.2.4, 1.2.5, 1.2.6
• Fix Version/s: 1.2.7
• Component/s: Performance
• Hadoop Flags: Reviewed
• Assignee: Rich Howarth
• Reporter: Rich Howarth
• Created: 19/Sep/17 12:30
• Updated: 01/Aug/18 06:23
• Resolved: 22/Sep/17 17:50

Description

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).

    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;
      }
    }

Issue Links

• is broken by: HBASE-15118 Fix findbugs complaint in hbase-server