org.apache.hadoop.hbase.master.balancer

Class StochasticLoadBalancer.RegionReplicaHostCostFunction

java.lang.Object

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

org.apache.hadoop.hbase.master.balancer.StochasticLoadBalancer.RegionReplicaHostCostFunction

Direct Known Subclasses:

StochasticLoadBalancer.RegionReplicaRackCostFunction

Enclosing class:

StochasticLoadBalancer

static class StochasticLoadBalancer.RegionReplicaHostCostFunction
extends StochasticLoadBalancer.CostFunction

A cost function for region replicas. We give a very high cost to hosting replicas of the same region in the same host. 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
(package private) long[]	costsPerGroup
private static float	DEFAULT_REGION_REPLICA_HOST_COST_KEY
(package private) long	maxCost
(package private) int[][]	primariesOfRegionsPerGroup
private static String	REGION_REPLICA_HOST_COST_KEY

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

cluster

Constructor Summary

Constructors

Constructor and Description
RegionReplicaHostCostFunction(org.apache.hadoop.conf.Configuration conf)

Method Summary

Modifier and Type	Method and Description
(package private) double	cost()
protected long	costPerGroup(int[] primariesOfRegions) For each primary region, it computes the total number of replicas in the array (numReplicas) and returns a sum of numReplicas-1 squared.
(package private) long	getMaxCost(BaseLoadBalancer.Cluster cluster)
(package private) void	init(BaseLoadBalancer.Cluster cluster) Called once per LB invocation to give the cost function to initialize it's state, and perform any costly calculation.
(package private) boolean	isNeeded()
protected void	regionMoved(int region, int oldServer, int newServer)

Methods inherited from class org.apache.hadoop.hbase.master.balancer.StochasticLoadBalancer.CostFunction

costFromArray, getMultiplier, postAction, scale, setMultiplier

Methods inherited from class java.lang.Object

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

Field Detail

REGION_REPLICA_HOST_COST_KEY

private static final String REGION_REPLICA_HOST_COST_KEY

See Also:

Constant Field Values

DEFAULT_REGION_REPLICA_HOST_COST_KEY

private static final float DEFAULT_REGION_REPLICA_HOST_COST_KEY

See Also:

Constant Field Values

maxCost

long maxCost

costsPerGroup

long[] costsPerGroup

primariesOfRegionsPerGroup

int[][] primariesOfRegionsPerGroup

Constructor Detail

RegionReplicaHostCostFunction

public RegionReplicaHostCostFunction(org.apache.hadoop.conf.Configuration conf)

Method Detail

init

void init(BaseLoadBalancer.Cluster cluster)

Description copied from class: StochasticLoadBalancer.CostFunction

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

Overrides:

init in class StochasticLoadBalancer.CostFunction

getMaxCost

long getMaxCost(BaseLoadBalancer.Cluster cluster)

isNeeded

boolean isNeeded()

Overrides:

isNeeded in class StochasticLoadBalancer.CostFunction

cost

double cost()

Specified by:

cost in class StochasticLoadBalancer.CostFunction

costPerGroup

protected long costPerGroup(int[] primariesOfRegions)

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:

primariesOfRegions - 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.

regionMoved

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

Overrides:

regionMoved in class StochasticLoadBalancer.CostFunction