[HBASE-10761] StochasticLoadBalancer still uses SimpleLoadBalancer's needBalance logic

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Implemented
• Affects Version/s: 0.98.0
• Component/s: Balancer
• Assignee: Unassigned
• Reporter: Victor Xu
• Created: 15/Mar/14 02:55
• Updated: 17/Jun/22 05:11
• Resolved: 12/Apr/19 03:33

Description

StochasticLoadBalancer has become the default balancer since 0.98.0. But its balanceCluster method still uses the BaseLoadBalancer.needBalance() which is originally designed for SimpleLoadBalancer. It's all based on the number of regions on the regionservers.
This can cause such a problem: when the cluster has some Hot Spot Region, the balance process may not be triggered because the numbers of regions on the RegionServers are averaged.