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https://issues.apache.org/jira/browse/HBASE-13082?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14995572#comment-14995572
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Hadoop QA commented on HBASE-13082:
-----------------------------------
{color:red}-1 overall{color}. Here are the results of testing the latest
attachment
http://issues.apache.org/jira/secure/attachment/12771229/HBASE-13082_13.patch
against master branch at commit 305ecaf224340b0f6e248d4fdabf0b53e1cd3b03.
ATTACHMENT ID: 12771229
{color:green}+1 @author{color}. The patch does not contain any @author
tags.
{color:green}+1 tests included{color}. The patch appears to include 46 new
or modified tests.
{color:green}+1 hadoop versions{color}. The patch compiles with all
supported hadoop versions (2.4.0 2.4.1 2.5.0 2.5.1 2.5.2 2.6.0 2.6.1 2.7.0
2.7.1)
{color:green}+1 javac{color}. The applied patch does not increase the
total number of javac compiler warnings.
{color:green}+1 protoc{color}. The applied patch does not increase the
total number of protoc compiler warnings.
{color:green}+1 javadoc{color}. The javadoc tool did not generate any
warning messages.
{color:red}-1 checkstyle{color}. The applied patch generated
1728 checkstyle errors (more than the master's current 1726 errors).
{color:green}+1 findbugs{color}. The patch does not introduce any new
Findbugs (version 2.0.3) warnings.
{color:green}+1 release audit{color}. The applied patch does not increase
the total number of release audit warnings.
{color:green}+1 lineLengths{color}. The patch does not introduce lines
longer than 100
{color:green}+1 site{color}. The mvn post-site goal succeeds with this patch.
{color:red}-1 core tests{color}. The patch failed these unit tests:
Test results:
https://builds.apache.org/job/PreCommit-HBASE-Build/16451//testReport/
Release Findbugs (version 2.0.3) warnings:
https://builds.apache.org/job/PreCommit-HBASE-Build/16451//artifact/patchprocess/newFindbugsWarnings.html
Checkstyle Errors:
https://builds.apache.org/job/PreCommit-HBASE-Build/16451//artifact/patchprocess/checkstyle-aggregate.html
Console output:
https://builds.apache.org/job/PreCommit-HBASE-Build/16451//console
This message is automatically generated.
> Coarsen StoreScanner locks to RegionScanner
> -------------------------------------------
>
> Key: HBASE-13082
> URL: https://issues.apache.org/jira/browse/HBASE-13082
> Project: HBase
> Issue Type: Bug
> Reporter: Lars Hofhansl
> Assignee: ramkrishna.s.vasudevan
> Attachments: 13082-test.txt, 13082-v2.txt, 13082-v3.txt,
> 13082-v4.txt, 13082.txt, 13082.txt, HBASE-13082.pdf, HBASE-13082_1.pdf,
> HBASE-13082_12.patch, HBASE-13082_13.patch, HBASE-13082_1_WIP.patch,
> HBASE-13082_2.pdf, HBASE-13082_2_WIP.patch, HBASE-13082_3.patch,
> HBASE-13082_4.patch, HBASE-13082_9.patch, HBASE-13082_9.patch, gc.png,
> gc.png, gc.png, hits.png, next.png, next.png
>
>
> Continuing where HBASE-10015 left of.
> We can avoid locking (and memory fencing) inside StoreScanner by deferring to
> the lock already held by the RegionScanner.
> In tests this shows quite a scan improvement and reduced CPU (the fences make
> the cores wait for memory fetches).
> There are some drawbacks too:
> * All calls to RegionScanner need to be remain synchronized
> * Implementors of coprocessors need to be diligent in following the locking
> contract. For example Phoenix does not lock RegionScanner.nextRaw() and
> required in the documentation (not picking on Phoenix, this one is my fault
> as I told them it's OK)
> * possible starving of flushes and compaction with heavy read load.
> RegionScanner operations would keep getting the locks and the
> flushes/compactions would not be able finalize the set of files.
> I'll have a patch soon.
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