[HBASE-8432] a table with unbalanced regions will balance indefinitely with the 'org.apache.hadoop.hbase.master.DefaultLoadBalancer'

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.94.5
• Fix Version/s: 0.98.0, 0.95.2, 0.94.10
• Component/s: Balancer
• Labels: patch

Environment

Linux 2.6.32-el5.x86_64

• Assignee: Unassigned
• Reporter: Wang Qiang
• Created: 25/Apr/13 03:50
• Updated: 24/Jul/13 19:08
• Resolved: 19/Jul/13 16:55

Description

it happened that a table with unbalanced regions, as follows in my cluster(the cluster has 20 regionservers, the table has 12 regions):
http://hadoopdev19.cm6:60030/ 1
http://hadoopdev8.cm6:60030/ 2
http://hadoopdev17.cm6:60030/ 1
http://hadoopdev12.cm6:60030/ 1
http://hadoopdev5.cm6:60030/ 1
http://hadoopdev9.cm6:60030/ 1
http://hadoopdev22.cm6:60030/ 1
http://hadoopdev11.cm6:60030/ 1
http://hadoopdev21.cm6:60030/ 1
http://hadoopdev16.cm6:60030/ 1
http://hadoopdev10.cm6:60030/ 1
with the 'org.apache.hadoop.hbase.master.DefaultLoadBalancer', after 5 times load-balances, the table are still unbalanced:
http://hadoopdev3.cm6:60030/ 1
http://hadoopdev20.cm6:60030/ 1
http://hadoopdev4.cm6:60030/ 2
http://hadoopdev18.cm6:60030/ 1
http://hadoopdev12.cm6:60030/ 1
http://hadoopdev14.cm6:60030/ 1
http://hadoopdev15.cm6:60030/ 1
http://hadoopdev6.cm6:60030/ 1
http://hadoopdev13.cm6:60030/ 1
http://hadoopdev11.cm6:60030/ 1
http://hadoopdev10.cm6:60030/ 1

http://hadoopdev19.cm6:60030/ 1
http://hadoopdev17.cm6:60030/ 1
http://hadoopdev8.cm6:60030/ 1
http://hadoopdev5.cm6:60030/ 1
http://hadoopdev12.cm6:60030/ 1
http://hadoopdev22.cm6:60030/ 1
http://hadoopdev11.cm6:60030/ 1
http://hadoopdev21.cm6:60030/ 1
http://hadoopdev7.cm6:60030/ 2
http://hadoopdev10.cm6:60030/ 1
http://hadoopdev16.cm6:60030/ 1

http://hadoopdev3.cm6:60030/ 1
http://hadoopdev20.cm6:60030/ 1
http://hadoopdev4.cm6:60030/ 1
http://hadoopdev18.cm6:60030/ 2
http://hadoopdev12.cm6:60030/ 1
http://hadoopdev14.cm6:60030/ 1
http://hadoopdev15.cm6:60030/ 1
http://hadoopdev6.cm6:60030/ 1
http://hadoopdev13.cm6:60030/ 1
http://hadoopdev11.cm6:60030/ 1
http://hadoopdev10.cm6:60030/ 1

http://hadoopdev19.cm6:60030/ 1
http://hadoopdev8.cm6:60030/ 1
http://hadoopdev17.cm6:60030/ 1
http://hadoopdev12.cm6:60030/ 1
http://hadoopdev5.cm6:60030/ 1
http://hadoopdev22.cm6:60030/ 1
http://hadoopdev11.cm6:60030/ 1
http://hadoopdev7.cm6:60030/ 1
http://hadoopdev21.cm6:60030/ 2
http://hadoopdev16.cm6:60030/ 1
http://hadoopdev10.cm6:60030/ 1

http://hadoopdev3.cm6:60030/ 1
http://hadoopdev20.cm6:60030/ 1
http://hadoopdev18.cm6:60030/ 1
http://hadoopdev4.cm6:60030/ 1
http://hadoopdev12.cm6:60030/ 1
http://hadoopdev15.cm6:60030/ 1
http://hadoopdev14.cm6:60030/ 2
http://hadoopdev6.cm6:60030/ 1
http://hadoopdev13.cm6:60030/ 1
http://hadoopdev11.cm6:60030/ 1
http://hadoopdev10.cm6:60030/ 1

from the above logs, we can also find that some regions needn't move, but they moved. follow into 'org.apache.hadoop.hbase.master.DefaultLoadBalancer.balanceCluster()', I found that 'maxToTake' is error calculated.