[HBASE-17515] Reduce memory footprint of RegionLoads kept by StochasticLoadBalancer

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 2.0.0
• Hadoop Flags: Reviewed
• Assignee: Tim Brown
• Reporter: Ted Yu
• Created: 23/Jan/17 18:42
• Updated: 26/Jan/17 23:54
• Resolved: 26/Jan/17 20:56

Description

Currently StochasticLoadBalancer uses the following fields of RegionLoad :

      return rl.getReadRequestsCount();
      return rl.getWriteRequestsCount();
      return rl.getMemStoreSizeMB();
      return rl.getStorefileSizeMB();

However, RegionLoad refers to ClusterStatusProtos.RegionLoad which has 18 fields.

This means we keep hbase.master.balancer.stochastic.numRegionLoadsToRemember (default value 15) RegionLoad's in memory but only use a small portion of them.

This JIRA is to consider creating POJO which wraps the above 4 fields so that the memory footprint can be lowered.

Lowering memory footprint would allow wider sliding window to be configured for load balancer while limiting the impact to heap consumption.