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https://issues.apache.org/jira/browse/HIVE-4318?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13629242#comment-13629242
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Kevin Wilfong commented on HIVE-4318:
-------------------------------------
The preProcessCounter and postProcessCounter weren't added for operator hooks,
they were preexisting, and it doesn't look like they were modified by the diff
either.
http://svn.apache.org/viewvc/hive/trunk/ql/src/java/org/apache/hadoop/hive/ql/exec/Operator.java?r1=1404933&r2=1438825
Could you try your experiment again just removing those two method calls and
not enterOperatorHooks and exitOperatorHooks. Those two methods look really
cheap if there are not operator hooks (they just check if the list is null and
return).
I just want to make sure if anything is removed, we're not removing too much.
> OperatorHooks hit performance even when not used
> ------------------------------------------------
>
> Key: HIVE-4318
> URL: https://issues.apache.org/jira/browse/HIVE-4318
> Project: Hive
> Issue Type: Bug
> Components: Query Processor
> Environment: Ubuntu LXC (64 bit)
> Reporter: Gopal V
> Assignee: Gunther Hagleitner
> Attachments: HIVE-4318.1.patch
>
>
> Operator Hooks inserted into Operator.java cause a performance hit even when
> it is not being used.
> For a count(1) query tested with & without the operator hook calls.
> {code:title=with}
> 2013-04-09 07:33:58,920 Stage-1 map = 100%, reduce = 100%, Cumulative CPU
> 84.07 sec
> Total MapReduce CPU Time Spent: 1 minutes 24 seconds 70 msec
> OK
> 28800991
> Time taken: 40.407 seconds, Fetched: 1 row(s)
> {code}
> {code:title=without}
> 2013-04-09 07:33:02,355 Stage-1 map = 100%, reduce = 100%, Cumulative CPU
> 68.48 sec
> ...
> Total MapReduce CPU Time Spent: 1 minutes 8 seconds 480 msec
> OK
> 28800991
> Time taken: 35.907 seconds, Fetched: 1 row(s)
> {code}
> The effect is multiplied by the number of operators in the pipeline that has
> to forward the row - the more operators there are the, the slower the query.
> The modification made to test this was
> {code:title=Operator.java}
> --- ql/src/java/org/apache/hadoop/hive/ql/exec/Operator.java
> +++ ql/src/java/org/apache/hadoop/hive/ql/exec/Operator.java
> @@ -526,16 +526,16 @@ public void process(Object row, int tag) throws
> HiveException {
> return;
> }
> OperatorHookContext opHookContext = new OperatorHookContext(this, row,
> tag);
> - preProcessCounter();
> - enterOperatorHooks(opHookContext);
> + //preProcessCounter();
> + //enterOperatorHooks(opHookContext);
> processOp(row, tag);
> - exitOperatorHooks(opHookContext);
> - postProcessCounter();
> + //exitOperatorHooks(opHookContext);
> + //postProcessCounter();
> }
> {code}
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