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https://issues.apache.org/jira/browse/HBASE-12590?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14227150#comment-14227150
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Hadoop QA commented on HBASE-12590:
-----------------------------------
{color:red}-1 overall{color}. Here are the results of testing the latest
attachment
http://issues.apache.org/jira/secure/attachment/12683981/HBase-12590-v1.patch
against master branch at commit f0d95e7f11403d67b4fc3f1fd4ef048047b6842a.
ATTACHMENT ID: 12683981
{color:green}+1 @author{color}. The patch does not contain any @author
tags.
{color:green}+1 tests included{color}. The patch appears to include 6 new
or modified tests.
{color:red}-1 javac{color}. The patch appears to cause mvn compile goal to
fail.
Compilation errors resume:
[ERROR] COMPILATION ERROR :
[ERROR]
/home/jenkins/jenkins-slave/workspace/PreCommit-HBASE-Build/hbase-server/src/main/java/org/apache/hadoop/hbase/mapreduce/TableInputFormatBase.java:[45,48]
cannot find symbol
[ERROR] Failed to execute goal
org.apache.maven.plugins:maven-compiler-plugin:3.2:compile (default-compile) on
project hbase-server: Compilation failure
[ERROR]
/home/jenkins/jenkins-slave/workspace/PreCommit-HBASE-Build/hbase-server/src/main/java/org/apache/hadoop/hbase/mapreduce/TableInputFormatBase.java:[45,48]
cannot find symbol
[ERROR] symbol: class HLog
[ERROR] location: package org.apache.hadoop.hbase.regionserver.wal
[ERROR] -> [Help 1]
[ERROR]
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e
switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR]
[ERROR] For more information about the errors and possible solutions, please
read the following articles:
[ERROR] [Help 1]
http://cwiki.apache.org/confluence/display/MAVEN/MojoFailureException
[ERROR]
[ERROR] After correcting the problems, you can resume the build with the command
[ERROR] mvn <goals> -rf :hbase-server
Console output:
https://builds.apache.org/job/PreCommit-HBASE-Build/11848//console
This message is automatically generated.
> A solution for data skew in HBase-Mapreduce Job
> ------------------------------------------------
>
> Key: HBASE-12590
> URL: https://issues.apache.org/jira/browse/HBASE-12590
> Project: HBase
> Issue Type: Improvement
> Components: mapreduce
> Affects Versions: 2.0.0
> Reporter: Weichen Ye
> Attachments: A Solution for Data Skew in HBase-MapReduce Job.pdf,
> HBase-12590-v1.patch
>
>
> 1, Motivation
> In production environment, data skew is a very common case. A HBase table
> always contains a lot of small regions and several large regions. Small
> regions waste a lot of computing resources. If we use a job to scan a table
> with 3000 small regions, we need a job with 3000 mappers. Large regions
> always block the job. If in a 100-region table, one region is far larger then
> the other 99 regions. When we run a job with the table as input, 99 mappers
> will be completed very quickly, and we need to wait for the last mapper for a
> long time.
> 2, Configuration
> Add two new configuration.
> hbase.mapreduce.split.autobalance = true means enabling the “auto balance” in
> HBase-MapReduce jobs. The default value is false.
> hbase.mapreduce.split.targetsize = 1073741824 (default 1GB). The target size
> of mapreduce splits.
> If a region size is large than the target size, cut the region into two
> split.If the sum of several small continuous region size less than the target
> size, combine these regions into one split.
> Example:
> In attachment
> Welcome to the Review Board.
> https://reviews.apache.org/r/28494/diff/#
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