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https://issues.apache.org/jira/browse/HBASE-18164?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16063652#comment-16063652
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Hadoop QA commented on HBASE-18164:
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|| Vote || Subsystem || Runtime || Comment ||
| {color:blue}0{color} | {color:blue} reexec {color} | {color:blue} 21m 58s
{color} | {color:blue} Docker mode activated. {color} |
| {color:blue}0{color} | {color:blue} patch {color} | {color:blue} 0m 2s
{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:red}-1{color} | {color:red} patch {color} | {color:red} 0m 18s {color}
| {color:red} HBASE-18164 does not apply to branch-1. Rebase required? Wrong
Branch? See https://yetus.apache.org/documentation/0.3.0/precommit-patchnames
for help. {color} |
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|| Subsystem || Report/Notes ||
| Docker | Client=1.13.1 Server=1.13.1 Image:yetus/hbase:395d9a0 |
| JIRA Patch URL |
https://issues.apache.org/jira/secure/attachment/12874541/18164.branch-1.addendum.txt
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| JIRA Issue | HBASE-18164 |
| Console output |
https://builds.apache.org/job/PreCommit-HBASE-Build/7338/console |
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This message was automatically generated.
> Much faster locality cost function and candidate generator
> ----------------------------------------------------------
>
> Key: HBASE-18164
> URL: https://issues.apache.org/jira/browse/HBASE-18164
> Project: HBase
> Issue Type: Improvement
> Components: Balancer
> Reporter: Kahlil Oppenheimer
> Assignee: Kahlil Oppenheimer
> Priority: Critical
> Fix For: 3.0.0, 1.4.0, 2.0.0-alpha-2
>
> Attachments: 18164.branch-1.addendum.txt, HBASE-18164-00.patch,
> HBASE-18164-01.patch, HBASE-18164-02.patch, HBASE-18164-04.patch,
> HBASE-18164-05.patch, HBASE-18164-06.patch, HBASE-18164-07.patch,
> HBASE-18164-08.patch
>
>
> We noticed that during the stochastic load balancer was not scaling well with
> cluster size. That is to say that on our smaller clusters (~17 tables, ~12
> region servers, ~5k regions), the balancer considers ~100,000 cluster
> configurations in 60s per balancer run, but only ~5,000 per 60s on our bigger
> clusters (~82 tables, ~160 region servers, ~13k regions) .
> Because of this, our bigger clusters are not able to converge on balance as
> quickly for things like table skew, region load, etc. because the balancer
> does not have enough time to "think".
> We have re-written the locality cost function to be incremental, meaning it
> only recomputes cost based on the most recent region move proposed by the
> balancer, rather than recomputing the cost across all regions/servers every
> iteration.
> Further, we also cache the locality of every region on every server at the
> beginning of the balancer's execution for both the LocalityBasedCostFunction
> and the LocalityCandidateGenerator to reference. This way, they need not
> collect all HDFS blocks of every region at each iteration of the balancer.
> The changes have been running in all 6 of our production clusters and all 4
> QA clusters without issue. The speed improvements we noticed are massive. Our
> big clusters now consider 20x more cluster configurations.
> One design decision I made is to consider locality cost as the difference
> between the best locality that is possible given the current cluster state,
> and the currently measured locality. The old locality computation would
> measure the locality cost as the difference from the current locality and
> 100% locality, but this new computation instead takes the difference between
> the current locality for a given region and the best locality for that region
> in the cluster.
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