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https://issues.apache.org/jira/browse/HBASE-17565?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15852150#comment-15852150
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Hadoop QA commented on HBASE-17565:
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| (/) *{color:green}+1 overall{color}* |
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|| Vote || Subsystem || Runtime || Comment ||
| {color:blue}0{color} | {color:blue} reexec {color} | {color:blue} 0m 14s 
{color} | {color:blue} Docker mode activated. {color} |
| {color:blue}0{color} | {color:blue} patch {color} | {color:blue} 0m 6s 
{color} | {color:blue} The patch file was not named according to hbase's naming 
conventions. Please see 
https://yetus.apache.org/documentation/0.3.0/precommit-patchnames for 
instructions. {color} |
| {color:green}+1{color} | {color:green} hbaseanti {color} | {color:green} 0m 
0s {color} | {color:green} Patch does not have any anti-patterns. {color} |
| {color:green}+1{color} | {color:green} @author {color} | {color:green} 0m 0s 
{color} | {color:green} The patch does not contain any @author tags. {color} |
| {color:green}+1{color} | {color:green} test4tests {color} | {color:green} 0m 
0s {color} | {color:green} The patch appears to include 2 new or modified test 
files. {color} |
| {color:green}+1{color} | {color:green} mvninstall {color} | {color:green} 2m 
42s {color} | {color:green} master passed {color} |
| {color:green}+1{color} | {color:green} compile {color} | {color:green} 0m 33s 
{color} | {color:green} master passed {color} |
| {color:green}+1{color} | {color:green} checkstyle {color} | {color:green} 0m 
38s {color} | {color:green} master passed {color} |
| {color:green}+1{color} | {color:green} mvneclipse {color} | {color:green} 0m 
15s {color} | {color:green} master passed {color} |
| {color:green}+1{color} | {color:green} findbugs {color} | {color:green} 1m 
31s {color} | {color:green} master passed {color} |
| {color:green}+1{color} | {color:green} javadoc {color} | {color:green} 0m 25s 
{color} | {color:green} master passed {color} |
| {color:green}+1{color} | {color:green} mvninstall {color} | {color:green} 0m 
36s {color} | {color:green} the patch passed {color} |
| {color:green}+1{color} | {color:green} compile {color} | {color:green} 0m 33s 
{color} | {color:green} the patch passed {color} |
| {color:green}+1{color} | {color:green} javac {color} | {color:green} 0m 33s 
{color} | {color:green} the patch passed {color} |
| {color:green}+1{color} | {color:green} checkstyle {color} | {color:green} 0m 
39s {color} | {color:green} the patch passed {color} |
| {color:green}+1{color} | {color:green} mvneclipse {color} | {color:green} 0m 
14s {color} | {color:green} the patch passed {color} |
| {color:green}+1{color} | {color:green} whitespace {color} | {color:green} 0m 
0s {color} | {color:green} The patch has no whitespace issues. {color} |
| {color:green}+1{color} | {color:green} hadoopcheck {color} | {color:green} 
24m 29s {color} | {color:green} Patch does not cause any errors with Hadoop 
2.6.1 2.6.2 2.6.3 2.6.4 2.6.5 2.7.1 2.7.2 2.7.3 or 3.0.0-alpha1. {color} |
| {color:green}+1{color} | {color:green} findbugs {color} | {color:green} 1m 
39s {color} | {color:green} the patch passed {color} |
| {color:green}+1{color} | {color:green} javadoc {color} | {color:green} 0m 26s 
{color} | {color:green} the patch passed {color} |
| {color:green}+1{color} | {color:green} unit {color} | {color:green} 80m 25s 
{color} | {color:green} hbase-server in the patch passed. {color} |
| {color:green}+1{color} | {color:green} asflicense {color} | {color:green} 0m 
16s {color} | {color:green} The patch does not generate ASF License warnings. 
{color} |
| {color:black}{color} | {color:black} {color} | {color:black} 116m 0s {color} 
| {color:black} {color} |
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|| Subsystem || Report/Notes ||
| Docker | Client=1.12.3 Server=1.12.3 Image:yetus/hbase:8d52d23 |
| JIRA Patch URL | 
https://issues.apache.org/jira/secure/attachment/12850875/17565.v3.txt |
| JIRA Issue | HBASE-17565 |
| Optional Tests |  asflicense  javac  javadoc  unit  findbugs  hadoopcheck  
hbaseanti  checkstyle  compile  |
| uname | Linux b22c644930b8 4.4.0-43-generic #63-Ubuntu SMP Wed Oct 12 
13:48:03 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux |
| Build tool | maven |
| Personality | 
/home/jenkins/jenkins-slave/workspace/PreCommit-HBASE-Build/component/dev-support/hbase-personality.sh
 |
| git revision | master / 1159296 |
| Default Java | 1.8.0_121 |
| findbugs | v3.0.0 |
|  Test Results | 
https://builds.apache.org/job/PreCommit-HBASE-Build/5566/testReport/ |
| modules | C: hbase-server U: hbase-server |
| Console output | 
https://builds.apache.org/job/PreCommit-HBASE-Build/5566/console |
| Powered by | Apache Yetus 0.3.0   http://yetus.apache.org |


This message was automatically generated.



> StochasticLoadBalancer may incorrectly skip balancing due to skewed 
> multiplier sum
> ----------------------------------------------------------------------------------
>
>                 Key: HBASE-17565
>                 URL: https://issues.apache.org/jira/browse/HBASE-17565
>             Project: HBase
>          Issue Type: Bug
>            Reporter: Ted Yu
>            Assignee: Ted Yu
>            Priority: Critical
>             Fix For: 2.0.0, 1.4.0
>
>         Attachments: 17565.v1.txt, 17565.v2.txt, 17565.v3.txt
>
>
> I was investigating why a 6 node cluster kept skipping balancing requests.
> Here were the region counts on the servers:
> 449, 448, 447, 449, 453, 0
> {code}
> 2017-01-26 22:04:47,145 INFO  
> [RpcServer.deafult.FPBQ.Fifo.handler=1,queue=0,port=16000] 
> balancer.StochasticLoadBalancer: Skipping load balancing because balanced 
> cluster; total cost is 127.0171157050385, sum multiplier is 111087.0 min cost 
> which need balance is 0.05
> {code}
> The big multiplier sum caught my eyes. Here was what additional debug logging 
> showed:
> {code}
> 2017-01-27 23:25:31,749 DEBUG 
> [RpcServer.deafult.FPBQ.Fifo.handler=9,queue=0,port=16000] 
> balancer.StochasticLoadBalancer: class 
> org.apache.hadoop.hbase.master.balancer.          
> StochasticLoadBalancer$RegionReplicaHostCostFunction with multiplier 100000.0
> 2017-01-27 23:25:31,749 DEBUG 
> [RpcServer.deafult.FPBQ.Fifo.handler=9,queue=0,port=16000] 
> balancer.StochasticLoadBalancer: class 
> org.apache.hadoop.hbase.master.balancer.          
> StochasticLoadBalancer$RegionReplicaRackCostFunction with multiplier 10000.0
> {code}
> Note however, that no table in the cluster used read replica.
> I can think of two ways of fixing this situation:
> 1. If there is no read replica in the cluster, ignore the multipliers for the 
> above two functions.
> 2. When cost() returned by the CostFunction is 0 (or very very close to 0.0), 
> ignore the multiplier.



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