org.apache.hadoop.hbase.master.balancer

Class HeterogeneousRegionCountCostFunction

java.lang.Object

org.apache.hadoop.hbase.master.balancer.HeterogeneousRegionCountCostFunction

@InterfaceAudience.Private
public class HeterogeneousRegionCountCostFunction
extends Object

This is an optional Cost function designed to allow region count skew across RegionServers. A rule file is loaded from the local FS or HDFS before balancing. It contains lines of rules. A rule is composed of a regexp for hostname, and a limit. For example, we could have:

* rs[0-9] 200 * rs1[0-9] 50

RegionServers with hostname matching the first rules will have a limit of 200, and the others 50. If there's no match, a default is set. The costFunction is trying to fill all RegionServers linearly, meaning that if the global usage is at 50%, then all RegionServers should hold half of their capacity in terms of regions. In order to use this CostFunction, you need to set the following options:

• hbase.master.balancer.stochastic.additionalCostFunctions
• hbase.master.balancer.stochastic.heterogeneousRegionCountRulesFile
• hbase.master.balancer.stochastic.heterogeneousRegionCountDefault

The rule file can be located on local FS or HDFS, depending on the prefix (file//: or hdfs://).

Field Summary

Fields

Modifier and Type	Field and Description
protected org.apache.hadoop.hbase.master.balancer.BalancerClusterState	cluster
static double	COST_EPSILON

Method Summary

Modifier and Type	Method and Description
protected double	cost()
protected void	regionMoved(int region, int oldServer, int newServer)
protected static double	scale(double min, double max, double value) Scale the value between 0 and 1.
void	updateWeight(double[] weights) Add the cost of this cost function to the weight of the candidate generator that is optimized for this cost function.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

COST_EPSILON

public static final double COST_EPSILON

See Also:

Constant Field Values

cluster

protected org.apache.hadoop.hbase.master.balancer.BalancerClusterState cluster

Method Detail

cost

protected double cost()

regionMoved

protected void regionMoved(int region,
                           int oldServer,
                           int newServer)

updateWeight

public void updateWeight(double[] weights)

Add the cost of this cost function to the weight of the candidate generator that is optimized for this cost function. By default it is the RandomCandiateGenerator for a cost function. Called once per init or after postAction.

Parameters:

weights - the weights for every generator.

scale

protected static double scale(double min,
                              double max,
                              double value)

Scale the value between 0 and 1.

Parameters:

min - Min value

max - The Max value

value - The value to be scaled.

Returns:

The scaled value.