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https://issues.apache.org/jira/browse/HBASE-8639?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13669465#comment-13669465
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Hadoop QA commented on HBASE-8639:
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{color:red}-1 overall{color}. Here are the results of testing the latest
attachment
http://issues.apache.org/jira/secure/attachment/12585234/8639-v1.txt
against trunk revision .
{color:green}+1 @author{color}. The patch does not contain any @author
tags.
{color:red}-1 tests included{color}. The patch doesn't appear to include
any new or modified tests.
Please justify why no new tests are needed for this
patch.
Also please list what manual steps were performed to
verify this patch.
{color:green}+1 hadoop1.0{color}. The patch compiles against the hadoop
1.0 profile.
{color:green}+1 hadoop2.0{color}. The patch compiles against the hadoop
2.0 profile.
{color:green}+1 javadoc{color}. The javadoc tool did not generate any
warning messages.
{color:green}+1 javac{color}. The applied patch does not increase the
total number of javac compiler warnings.
{color:green}+1 findbugs{color}. The patch does not introduce any new
Findbugs (version 1.3.9) 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 site goal succeeds with this patch.
{color:green}+1 core tests{color}. The patch passed unit tests in .
Test results:
https://builds.apache.org/job/PreCommit-HBASE-Build/5867//testReport/
Findbugs warnings:
https://builds.apache.org/job/PreCommit-HBASE-Build/5867//artifact/trunk/patchprocess/newPatchFindbugsWarningshbase-prefix-tree.html
Findbugs warnings:
https://builds.apache.org/job/PreCommit-HBASE-Build/5867//artifact/trunk/patchprocess/newPatchFindbugsWarningshbase-client.html
Findbugs warnings:
https://builds.apache.org/job/PreCommit-HBASE-Build/5867//artifact/trunk/patchprocess/newPatchFindbugsWarningshbase-common.html
Findbugs warnings:
https://builds.apache.org/job/PreCommit-HBASE-Build/5867//artifact/trunk/patchprocess/newPatchFindbugsWarningshbase-protocol.html
Findbugs warnings:
https://builds.apache.org/job/PreCommit-HBASE-Build/5867//artifact/trunk/patchprocess/newPatchFindbugsWarningshbase-server.html
Findbugs warnings:
https://builds.apache.org/job/PreCommit-HBASE-Build/5867//artifact/trunk/patchprocess/newPatchFindbugsWarningshbase-hadoop1-compat.html
Findbugs warnings:
https://builds.apache.org/job/PreCommit-HBASE-Build/5867//artifact/trunk/patchprocess/newPatchFindbugsWarningshbase-examples.html
Findbugs warnings:
https://builds.apache.org/job/PreCommit-HBASE-Build/5867//artifact/trunk/patchprocess/newPatchFindbugsWarningshbase-hadoop-compat.html
Console output:
https://builds.apache.org/job/PreCommit-HBASE-Build/5867//console
This message is automatically generated.
> very poor performance of htable.getscanner in multithread env.
> --------------------------------------------------------------
>
> Key: HBASE-8639
> URL: https://issues.apache.org/jira/browse/HBASE-8639
> Project: HBase
> Issue Type: Bug
> Affects Versions: 0.94.7
> Reporter: Raymond Liu
> Assignee: Ted Yu
> Attachments: 8639-v1.txt
>
>
> Hi, I am running a app on top of phoenix which will fork say around 100+
> thread to call htable.getscanner(scan) to do parallel scan ( say each scan is
> actually targeting one Region), And each scan will only match a few result
> and return thus will be very fast.
> under this case, I found that the htable.getscanner(scan) op itself runs
> pretty slow. by profiling with jvisualvm. I found 90% of app time is cost on
> org.apache.hadoop.net.DNS.getDefaultHost. Which been invoked by
> scannnercallable.checkIfRegionServerIsRemote.
> The root cause is that DNS.getDefaultHost involves synchronized methods in
> java.net.Inet4AddressImpl which have the 100+ thread to lock and wait upon
> each other. each call to DNS.getDefaultHost cost around 30ms, while in
> another case, I run single thread to call 100K times DNS.getDefaultHost ,
> each cost leas than 0.06ms.
> By hacking the code and remove the call to checkIfRegionServerIsRemote, my
> app runs 5 times faster, say, 50K op in my app cost 200+ seconds instead of
> 1000+ seconds.
> by check the code further, I found this checkIfRegionServerIsRemote seems
> just for use of metrics collection. ( or maybe retry logic?) I am wondering
> that could this been removed or switch to some other implementation? so that
> cases like mine which run large number of small scan with multi threads could
> performance way better?
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