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.primary - the primary balance defines a weight factor for the number of primaries of a specific index allocated on a 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 and Description
static class	BalancedShardsAllocator.Balancer A BalancedShardsAllocator.Balancer
static class	BalancedShardsAllocator.Operation An enum that donates the actual operation the BalancedShardsAllocator.WeightFunction is applied to.
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 and Description
static String	SETTING_INDEX_BALANCE_FACTOR
static String	SETTING_PRIMARY_BALANCE_FACTOR
static String	SETTING_SHARD_BALANCE_FACTOR
static String	SETTING_THRESHOLD

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

componentSettings, logger, settings

Constructor Summary

Constructors

Constructor and Description
BalancedShardsAllocator(Settings settings)
BalancedShardsAllocator(Settings settings, NodeSettingsService nodeSettingsService)

Method Summary

Modifier and Type	Method and Description
boolean	allocateUnassigned(RoutingAllocation allocation) Assign all unassigned shards to nodes
void	applyFailedShards(FailedRerouteAllocation allocation) Applies changes on failed nodes based on the implemented algorithm.
void	applyStartedShards(StartedRerouteAllocation allocation) Applies changes on started nodes based on the implemented algorithm.
float	getIndexBalance() Returns the index related weight factor.
float	getPrimaryBalance() Returns the primary related weight factor.
float	getShardBalance() Returns the shard related weight factor.
float	getThreshold() Returns the currently configured delta threshold
boolean	move(MutableShardRouting shardRouting, RoutingNode node, RoutingAllocation allocation) Moves a shard from the given node to other node.
boolean	rebalance(RoutingAllocation allocation) Rebalancing number of shards on all nodes

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

nodeName

Methods inherited from class java.lang.Object

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

Field Detail

SETTING_THRESHOLD

public static final String SETTING_THRESHOLD

See Also:

Constant Field Values

SETTING_INDEX_BALANCE_FACTOR

public static final String SETTING_INDEX_BALANCE_FACTOR

See Also:

Constant Field Values

SETTING_SHARD_BALANCE_FACTOR

public static final String SETTING_SHARD_BALANCE_FACTOR

See Also:

Constant Field Values

SETTING_PRIMARY_BALANCE_FACTOR

public static final String SETTING_PRIMARY_BALANCE_FACTOR

See Also:

Constant Field Values

Constructor Detail

BalancedShardsAllocator

public BalancedShardsAllocator(Settings settings)

BalancedShardsAllocator

@Inject
public BalancedShardsAllocator(Settings settings,
                                       NodeSettingsService nodeSettingsService)

Method Detail

applyStartedShards

public void applyStartedShards(StartedRerouteAllocation allocation)

Description copied from interface: ShardsAllocator

Applies changes on started nodes based on the implemented algorithm. For example if a shard has changed to ShardRoutingState.STARTED from ShardRoutingState.RELOCATING this allocator might apply some cleanups on the node that used to hold the shard.

Specified by:

applyStartedShards in interface ShardsAllocator

Parameters:

allocation - all started shards

applyFailedShards

public void applyFailedShards(FailedRerouteAllocation allocation)

Description copied from interface: ShardsAllocator

Applies changes on failed nodes based on the implemented algorithm.

Specified by:

applyFailedShards in interface ShardsAllocator

Parameters:

allocation - all failed shards

allocateUnassigned

public boolean allocateUnassigned(RoutingAllocation allocation)

Description copied from interface: ShardsAllocator

Assign all unassigned shards to nodes

Specified by:

allocateUnassigned in interface ShardsAllocator

Parameters:

allocation - current node allocation

Returns:

true if the allocation has changed, otherwise false

rebalance

public boolean rebalance(RoutingAllocation allocation)

Description copied from interface: ShardsAllocator

Rebalancing number of shards on all nodes

Specified by:

rebalance in interface ShardsAllocator

Parameters:

allocation - current node allocation

Returns:

true if the allocation has changed, otherwise false

move

public boolean move(MutableShardRouting shardRouting,
                    RoutingNode node,
                    RoutingAllocation allocation)

Description copied from interface: ShardsAllocator

Moves a shard from the given node to other node.

Specified by:

move in interface ShardsAllocator

Parameters:

shardRouting - the shard to move

node - A node containing the shard

allocation - current node allocation

Returns:

true if the allocation has changed, otherwise false

getThreshold

public float getThreshold()

Returns the currently configured delta threshold

getIndexBalance

public float getIndexBalance()

Returns the index related weight factor.

getPrimaryBalance

public float getPrimaryBalance()

Returns the primary related weight factor.

getShardBalance

public float getShardBalance()

Returns the shard related weight factor.