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https://issues.apache.org/jira/browse/HIVE-5018?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13756385#comment-13756385
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Thejas M Nair commented on HIVE-5018:
-------------------------------------
I haven't seen that checkstyle error you are seeing. I am not sure why it is
happening. You can try canceling the patch , uploading a new file and making it
patch available again to see if that happens on the pre-commit test environment
as well
I went through some of the changes, I see that you are trying to save on object
reference creation, such as the following -
{code}
---
a/hbase-handler/src/java/org/apache/hadoop/hive/hbase/HBaseStatsAggregator.java
+++
b/hbase-handler/src/java/org/apache/hadoop/hive/hbase/HBaseStatsAggregator.java
@@ -113,8 +113,9 @@ public boolean cleanUp(String rowID) {
scan.setFilter(filter);
ResultScanner scanner = htable.getScanner(scan);
ArrayList<Delete> toDelete = new ArrayList<Delete>();
+ Delete delete;
for (Result result : scanner) {
- Delete delete = new Delete(result.getRow());
+ delete = new Delete(result.getRow());
toDelete.add(delete);
}
htable.delete(toDelete);
{code}
While object creation has significant costs associated with it, I don't think
this reference re-use will have any real impact. A reference is like a pointer
in C/C++ , a memory location that stores the address of the object. JVM would
be able to re-use this memory location in the existing implementation. Can you
give more details of the arithmetic program you ran to check the performance
difference (including the code, total runtime, how many times you ran it)?
> Avoiding object instantiation in loops (issue 6)
> ------------------------------------------------
>
> Key: HIVE-5018
> URL: https://issues.apache.org/jira/browse/HIVE-5018
> Project: Hive
> Issue Type: Sub-task
> Reporter: Benjamin Jakobus
> Assignee: Benjamin Jakobus
> Priority: Minor
> Fix For: 0.12.0
>
> Attachments: HIVE-5018.1.patch.txt
>
>
> Object instantiation inside loops is very expensive. Where possible, object
> references should be created outside the loop so that they can be reused.
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