org.apache.hadoop.hbase.master.balancer

Class RegionReplicaGroupingCostFunction

java.lang.Object

org.apache.hadoop.hbase.master.balancer.CostFunction

org.apache.hadoop.hbase.master.balancer.RegionReplicaGroupingCostFunction

Direct Known Subclasses:

RegionReplicaHostCostFunction, RegionReplicaRackCostFunction

@InterfaceAudience.Private
abstract class RegionReplicaGroupingCostFunction
extends CostFunction

A cost function for region replicas. We give a high cost for hosting replicas of the same region in the same server, host or rack. We do not prevent the case though, since if numReplicas > numRegionServers, we still want to keep the replica open.

Field Summary

Fields

Modifier and Type	Field and Description
protected long[]	costsPerGroup
protected long	maxCost

Fields inherited from class org.apache.hadoop.hbase.master.balancer.CostFunction

cluster, COST_EPSILON

Constructor Summary

Constructors

Constructor and Description
RegionReplicaGroupingCostFunction()

Method Summary

Modifier and Type	Method and Description
protected double	cost()
protected long	costPerGroup(org.agrona.collections.Int2IntCounterMap colocatedReplicaCounts) For each primary region, it computes the total number of replicas in the array (numReplicas) and returns a sum of numReplicas-1 squared.
protected long	getMaxCost(BalancerClusterState cluster)
(package private) boolean	isNeeded()
protected abstract void	loadCosts()
(package private) void	prepare(BalancerClusterState cluster) Called once per LB invocation to give the cost function to initialize it's state, and perform any costly calculation.
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 org.apache.hadoop.hbase.master.balancer.CostFunction

getMultiplier, postAction, regionMoved, scale, setMultiplier

Methods inherited from class java.lang.Object

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

Field Detail

maxCost

protected long maxCost

costsPerGroup

protected long[] costsPerGroup

Constructor Detail

RegionReplicaGroupingCostFunction

RegionReplicaGroupingCostFunction()

Method Detail

prepare

final void prepare(BalancerClusterState cluster)

Description copied from class: CostFunction

Called once per LB invocation to give the cost function to initialize it's state, and perform any costly calculation.

Overrides:

prepare in class CostFunction

loadCosts

protected abstract void loadCosts()

getMaxCost

protected final long getMaxCost(BalancerClusterState cluster)

isNeeded

boolean isNeeded()

Overrides:

isNeeded in class CostFunction

cost

protected double cost()

Specified by:

cost in class CostFunction

costPerGroup

protected final long costPerGroup(org.agrona.collections.Int2IntCounterMap colocatedReplicaCounts)

For each primary region, it computes the total number of replicas in the array (numReplicas) and returns a sum of numReplicas-1 squared. For example, if the server hosts regions a, b, c, d, e, f where a and b are same replicas, and c,d,e are same replicas, it returns (2-1) * (2-1) + (3-1) * (3-1) + (1-1) * (1-1).

Parameters:

colocatedReplicaCounts - a sorted array of primary regions ids for the regions hosted

Returns:

a sum of numReplicas-1 squared for each primary region in the group.

updateWeight

public final void updateWeight(double[] weights)

Description copied from class: CostFunction

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.

Overrides:

updateWeight in class CostFunction

Parameters:

weights - the weights for every generator.