[HBASE-12928] BaseLoadBalancer#needsBalance only checks the sloppiness of region count before balancing

• Type: Improvement
• Status: Closed
• Priority: Minor
• Resolution: Incomplete
• Affects Version/s: 0.99.2
• Component/s: Balancer
• Assignee: Unassigned
• Reporter: Jianwei Cui
• Created: 27/Jan/15 02:10
• Updated: 17/Jun/22 18:54
• Resolved: 17/Jun/22 18:54

Description

BaseLoadBalancer#needsBalance will be invoked to judge whether needs to do balancing. StochasticLoadBalancer do balancing by considering region count skew cost, read/write request cost, locality cost, etc. However, it seems that only sloppiness of region count is checked in BaseLoadBalancer#needsBalance, there may be cases that request/locality cost is high when region count is even, this will skip the actual balancing so that can't achieve lower cost. There, Do we need to check sloppiness of other factors(read/write request, locality, etc) in needsBalance?