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https://issues.apache.org/jira/browse/HBASE-4031?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Jieshan Bean resolved HBASE-4031.
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Resolution: Duplicate
> An imbalance result calculated by LoadBalancer
> ----------------------------------------------
>
> Key: HBASE-4031
> URL: https://issues.apache.org/jira/browse/HBASE-4031
> Project: HBase
> Issue Type: Bug
> Components: master
> Affects Versions: 0.90.3
> Reporter: Jieshan Bean
> Fix For: 0.90.4
>
> Attachments: HMaster222.rar, HRegionServer222.rar
>
>
> I found the problem while the cluster couldn't balance(Around time of
> 2011-05-24 11:28).One node's regions count is the double of the other nodes.
> And it didn't move regions anymore:
> Address Start Code Load
> 158-1-101-202:20030 1306205409671 requests=0, regions=2593, usedHeap=114,
> maxHeap=8165 158-1-101-222:20030 1306205940117 requests=0, regions=5841,
> usedHeap=80, maxHeap=8165 158-1-101-52:20030 1306205417261 requests=0,
> regions=2622, usedHeap=76, maxHeap=8165 158-1-101-82:20030 1306205415714
> requests=0, regions=2633, usedHeap=69, maxHeap=8165
> Total: servers: 4 requests=0, regions=13689
> HBASE-3985-"Same Region could be picked out twice in LoadBalancer" was
> found by my analysis on this problem.
> But I'm afraid it's not the main cause of the problem.
> There's one active master, one standby master, four regionservers in our
> cluster.
> >>10:57:41, the standby hamster 222 becomes the active one.
> 2011-05-24 10:57:41,314 INFO org.apache.hadoop.hbase.master.HMaster: Master
> startup proceeding: master failover
> >>4 regionservers was registered in 222 one by one. Only one regionserver
> >>seemed some time late.
> 2011-05-24 10:57:37,533 INFO : Registering
> server=158-1-101-82,20020,1306205415714, regionCount=3388, userLoad=true
> 2011-05-24 10:57:37,537 INFO : Registering
> server=158-1-101-202,20020,1306205409671, regionCount=3453, userLoad=true
> 2011-05-24 10:57:37,598 INFO : Registering
> server=158-1-101-52,20020,1306205417261, regionCount=3411, userLoad=true
> 2011-05-24 10:59:00,408 INFO : Registering
> server=158-1-101-222,20020,1306205940117, regionCount=0, userLoad=false
> >>13134 regions needed to move after rebuildUserRegions(13689 regions in the
> >>cluster during the time).
> 2011-05-24 10:58:47,534 INFO
> org.apache.hadoop.hbase.master.AssignmentManager: Failed-over master needs to
> process 13134 regions in transition
> >>All the 13134 regions were opened, regions opened count in each server:
> 158-1-101-222,20020,1306205940117 Count: 834
> 158-1-101-82,20020,1306205415714 Count: 4093
> 158-1-101-202,20020,1306205409671 Count: 4118
> 158-1-101-52,20020,1306205417261 Count: 4089
> >>The nearest balancer calculate results:
> 2011-05-24 11:12:11,076 INFO org.apache.hadoop.hbase.master.LoadBalancer:
> Calculated a load balance in 19ms. Moving 5012 regions off of 3 overloaded
> servers onto 1 less loaded servers
> "5012" is an unimaginable number here, for it is larger than the average
> number "3424.5"
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