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From "Mostafa Mokhtar (JIRA)" <j...@apache.org>
Subject [jira] [Created] (HIVE-7574) CommonJoinOperator.checkAndGenObject calls LOG.info per row from probe side in a HashMap join consuming 4% of the CPU
Date Thu, 31 Jul 2014 19:42:38 GMT
Mostafa Mokhtar created HIVE-7574:
-------------------------------------

             Summary: CommonJoinOperator.checkAndGenObject calls LOG.info per row from probe
side in a HashMap join consuming 4% of the CPU
                 Key: HIVE-7574
                 URL: https://issues.apache.org/jira/browse/HIVE-7574
             Project: Hive
          Issue Type: Bug
          Components: HiveServer2
    Affects Versions: 0.13.1
            Reporter: Mostafa Mokhtar
             Fix For: 0.14.0


In Map join Log4JLogger.trace takes 4% of the CPU time as it gets called per row from the
probe side by CommonJoinOperator.genAllOneUniqueJoinObject.

Fix is to remove the logging code code below from CommonJoinOperator.genAllOneUniqueJoinObject:
{code}
if (allOne) {
        LOG.info("calling genAllOneUniqueJoinObject");
        genAllOneUniqueJoinObject();
        LOG.info("called genAllOneUniqueJoinObject");
      } else {
        LOG.trace("calling genUniqueJoinObject");
        genUniqueJoinObject(0, 0);
        LOG.trace("called genUniqueJoinObject");
      }
{code}

And 
{code}
    if (!hasEmpty && !mayHasMoreThanOne) {
        LOG.trace("calling genAllOneUniqueJoinObject");
        genAllOneUniqueJoinObject();
        LOG.trace("called genAllOneUniqueJoinObject");
      } else if (!hasEmpty && !hasLeftSemiJoin) {
        LOG.trace("calling genUniqueJoinObject");
        genUniqueJoinObject(0, 0);
        LOG.trace("called genUniqueJoinObject");
      } else {
        LOG.trace("calling genObject");
        genJoinObject();
        LOG.trace("called genObject");
      }
{code}


This is the call stack 
{code}
Stack Trace	Sample Count	Percentage(%)
hadoop.hive.ql.exec.MapJoinOperator.processOp(Object, int)	388	75.486
   hadoop.hive.ql.exec.CommonJoinOperator.checkAndGenObject()	121	23.541
      hadoop.hive.ql.exec.CommonJoinOperator.genAllOneUniqueJoinObject()	92	17.899
      commons.logging.impl.Log4JLogger.trace(Object)	20	3.891
         log4j.Category.log(String, Priority, Object, Throwable)	20	3.891
            log4j.Category.getEffectiveLevel()	10	1.946
{code}



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