Package org.elasticsearch.cluster.routing.allocation.allocator

Class BalancedShardsAllocator

java.lang.Object

org.elasticsearch.common.component.AbstractComponent

org.elasticsearch.cluster.routing.allocation.allocator.BalancedShardsAllocator

All Implemented Interfaces:

ShardsAllocator

public class BalancedShardsAllocator
extends AbstractComponent
implements ShardsAllocator

The BalancedShardsAllocator re-balances the nodes allocations within an cluster based on a BalancedShardsAllocator.WeightFunction. The clusters balance is defined by four parameters which can be set in the cluster update API that allows changes in real-time:

• cluster.routing.allocation.balance.shard - The shard balance defines the weight factor for shards allocated on a RoutingNode
• cluster.routing.allocation.balance.index - The index balance defines a factor to the number of ShardRoutings per index allocated on a specific node
• cluster.routing.allocation.balance.threshold - A threshold to set the minimal optimization value of operations that should be performed

These parameters are combined in a BalancedShardsAllocator.WeightFunction that allows calculation of node weights which are used to re-balance shards based on global as well as per-index factors.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	BalancedShardsAllocator.Balancer	A BalancedShardsAllocator.Balancer
static class	BalancedShardsAllocator.WeightFunction	This class is the primary weight function used to create balanced over nodes and shards in the cluster.

Field Summary

Fields

Modifier and Type	Field	Description
static Setting<java.lang.Float>	INDEX_BALANCE_FACTOR_SETTING
static Setting<java.lang.Float>	SHARD_BALANCE_FACTOR_SETTING
static Setting<java.lang.Float>	THRESHOLD_SETTING

Fields inherited from class org.elasticsearch.common.component.AbstractComponent

deprecationLogger, logger, settings

Constructor Summary

Constructors

Constructor	Description
BalancedShardsAllocator(Settings settings)
BalancedShardsAllocator(Settings settings, ClusterSettings clusterSettings)

Method Summary

Modifier and Type	Method	Description
void	allocate(RoutingAllocation allocation)	Allocates shards to nodes in the cluster.
ShardAllocationDecision	decideShardAllocation(ShardRouting shard, RoutingAllocation allocation)	Returns the decision for where a shard should reside in the cluster.
float	getIndexBalance()	Returns the index related weight factor.
float	getShardBalance()	Returns the shard related weight factor.
float	getThreshold()	Returns the currently configured delta threshold

Methods inherited from class org.elasticsearch.common.component.AbstractComponent

logDeprecatedSetting, logRemovedSetting, nodeName

Methods inherited from class java.lang.Object

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

Field Detail

INDEX_BALANCE_FACTOR_SETTING

public static final Setting<java.lang.Float> INDEX_BALANCE_FACTOR_SETTING

SHARD_BALANCE_FACTOR_SETTING

public static final Setting<java.lang.Float> SHARD_BALANCE_FACTOR_SETTING

THRESHOLD_SETTING

public static final Setting<java.lang.Float> THRESHOLD_SETTING

Constructor Detail

BalancedShardsAllocator

public BalancedShardsAllocator(Settings settings)

BalancedShardsAllocator

@Inject
public BalancedShardsAllocator(Settings settings,
                               ClusterSettings clusterSettings)

Method Detail

allocate

public void allocate(RoutingAllocation allocation)

Description copied from interface: ShardsAllocator

Allocates shards to nodes in the cluster. An implementation of this method should: - assign unassigned shards - relocate shards that cannot stay on a node anymore - relocate shards to find a good shard balance in the cluster

Specified by:

allocate in interface ShardsAllocator

Parameters:

allocation - current node allocation

decideShardAllocation

public ShardAllocationDecision decideShardAllocation(ShardRouting shard,
                                                     RoutingAllocation allocation)

Description copied from interface: ShardsAllocator

Returns the decision for where a shard should reside in the cluster. If the shard is unassigned, then the AllocateUnassignedDecision will be non-null. If the shard is not in the unassigned state, then the MoveDecision will be non-null. This method is primarily used by the cluster allocation explain API to provide detailed explanations for the allocation of a single shard. Implementations of the ShardsAllocator.allocate(RoutingAllocation) method may use the results of this method implementation to decide on allocating shards in the routing table to the cluster. If an implementation of this interface does not support explaining decisions for a single shard through the cluster explain API, then this method should throw a UnsupportedOperationException.

Specified by:

decideShardAllocation in interface ShardsAllocator

getThreshold

public float getThreshold()

Returns the currently configured delta threshold

getIndexBalance

public float getIndexBalance()

Returns the index related weight factor.

getShardBalance

public float getShardBalance()

Returns the shard related weight factor.