Module org.elasticsearch.server

Package org.elasticsearch.cluster.routing.allocation

Class AllocationService

java.lang.Object

org.elasticsearch.cluster.routing.allocation.AllocationService

public class AllocationService
extends Object

This service manages the node allocation of a cluster. For this reason the AllocationService keeps AllocationDeciders to choose nodes for shard allocation. This class also manages new nodes joining the cluster and rerouting of shards.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static final record	AllocationService.CommandsResult	this class is used to describe results of applying a set of AllocationCommand

Constructor Summary

Constructors

Constructor	Description
AllocationService(AllocationDeciders allocationDeciders, ShardsAllocator shardsAllocator, ClusterInfoService clusterInfoService, SnapshotsInfoService snapshotsInfoService, ShardRoutingRoleStrategy shardRoutingRoleStrategy)
AllocationService(AllocationDeciders allocationDeciders, GatewayAllocator gatewayAllocator, ShardsAllocator shardsAllocator, ClusterInfoService clusterInfoService, SnapshotsInfoService snapshotsInfoService, ShardRoutingRoleStrategy shardRoutingRoleStrategy)

Method Summary

Modifier and Type	Method	Description
ClusterState	adaptAutoExpandReplicas(ClusterState clusterState)	Checks if there are replicas with the auto-expand feature that need to be adapted.
ClusterState	applyFailedShards(ClusterState clusterState, List<FailedShard> failedShards, List<StaleShard> staleShards)	Applies the failed shards.
ClusterState	applyStartedShards(ClusterState clusterState, List<ShardRouting> startedShards)	Applies the started shards.
void	cleanCaches()
protected long	currentNanoTime()	override this to control time based decisions during allocation
ClusterState	disassociateDeadNodes(ClusterState clusterState, boolean reroute, String reason)	unassigned an shards that are associated with nodes that are no longer part of the cluster, potentially promoting replicas if needed.
ClusterState	executeWithRoutingAllocation(ClusterState clusterState, String reason, Consumer<RoutingAllocation> routingAllocationConsumer)	Computes the next step towards a fully allocated and balanced cluster and records this step in the routing table of the returned state.
ShardAllocationDecision	explainShardAllocation(ShardRouting shardRouting, RoutingAllocation allocation)
static <T> String	firstListElementsToCommaDelimitedString(List<T> elements, Function<T,String> formatter, boolean isDebugEnabled)	Internal helper to cap the number of elements in a potentially long list for logging.
AllocationDeciders	getAllocationDeciders()
static ClusterHealthStatus	getHealthStatus(ClusterState clusterState)
int	getNumberOfInFlightFetches()
ShardRoutingRoleStrategy	getShardRoutingRoleStrategy()
ClusterState	reroute(ClusterState clusterState, String reason, ActionListener<Void> listener)	Computes the next step towards a fully allocated and balanced cluster and records this step in the routing table of the returned state.
AllocationService.CommandsResult	reroute(ClusterState clusterState, AllocationCommands commands, boolean explain, boolean retryFailed, boolean dryRun, ActionListener<Void> reroute)
void	setExistingShardsAllocators(Map<String,ExistingShardsAllocator> existingShardsAllocators)	Inject the ExistingShardsAllocators to use.

Methods inherited from class java.lang.Object

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

Constructor Details

AllocationService

public AllocationService(AllocationDeciders allocationDeciders,
 GatewayAllocator gatewayAllocator,
 ShardsAllocator shardsAllocator,
 ClusterInfoService clusterInfoService,
 SnapshotsInfoService snapshotsInfoService,
 ShardRoutingRoleStrategy shardRoutingRoleStrategy)

AllocationService

public AllocationService(AllocationDeciders allocationDeciders,
 ShardsAllocator shardsAllocator,
 ClusterInfoService clusterInfoService,
 SnapshotsInfoService snapshotsInfoService,
 ShardRoutingRoleStrategy shardRoutingRoleStrategy)

Method Details

setExistingShardsAllocators

public void setExistingShardsAllocators(Map<String,ExistingShardsAllocator> existingShardsAllocators)

Inject the ExistingShardsAllocators to use. May only be called once.

getAllocationDeciders

public AllocationDeciders getAllocationDeciders()

Returns:

The allocation deciders that the allocation service has been configured with.

getShardRoutingRoleStrategy

public ShardRoutingRoleStrategy getShardRoutingRoleStrategy()

applyStartedShards

public ClusterState applyStartedShards(ClusterState clusterState,
 List<ShardRouting> startedShards)

Applies the started shards. Note, only initializing ShardRouting instances that exist in the routing table should be provided as parameter and no duplicates should be contained.

If the same instance of the ClusterState is returned, then no change has been made.

applyFailedShards

public ClusterState applyFailedShards(ClusterState clusterState,
 List<FailedShard> failedShards,
 List<StaleShard> staleShards)

Applies the failed shards. Note, only assigned ShardRouting instances that exist in the routing table should be provided as parameter. Also applies a list of allocation ids to remove from the in-sync set for shard copies for which there are no routing entries in the routing table.

If the same instance of ClusterState is returned, then no change has been made.

disassociateDeadNodes

public ClusterState disassociateDeadNodes(ClusterState clusterState,
 boolean reroute,
 String reason)

unassigned an shards that are associated with nodes that are no longer part of the cluster, potentially promoting replicas if needed.

adaptAutoExpandReplicas

public ClusterState adaptAutoExpandReplicas(ClusterState clusterState)

Checks if there are replicas with the auto-expand feature that need to be adapted. Returns an updated cluster state if changes were necessary, or the identical cluster if no changes were required.

firstListElementsToCommaDelimitedString

public static <T> String firstListElementsToCommaDelimitedString(List<T> elements,
 Function<T,String> formatter,
 boolean isDebugEnabled)

Internal helper to cap the number of elements in a potentially long list for logging.

Type Parameters:

T - The list element type.

Parameters:

elements - The elements to log. May be any non-null list. Must not be null.

formatter - A function that can convert list elements to a String. Must not be null.

Returns:

A comma-separated string of the first few elements.

reroute

public AllocationService.CommandsResult reroute(ClusterState clusterState,
 AllocationCommands commands,
 boolean explain,
 boolean retryFailed,
 boolean dryRun,
 ActionListener<Void> reroute)

reroute

public ClusterState reroute(ClusterState clusterState,
 String reason,
 ActionListener<Void> listener)

Computes the next step towards a fully allocated and balanced cluster and records this step in the routing table of the returned state. Should be called after every change to the cluster that affects the routing table and/or the balance of shards.

This method is expensive in larger clusters. Wherever possible you should invoke this method asynchronously using RerouteService.reroute(java.lang.String, org.elasticsearch.common.Priority, org.elasticsearch.action.ActionListener<org.elasticsearch.cluster.ClusterState>) to batch up invocations rather than calling the method directly. The node's reroute service is typically obtained from ClusterService.getRerouteService().

Returns:

an updated cluster state, or the same instance that was passed as an argument if no changes were made.

executeWithRoutingAllocation

public ClusterState executeWithRoutingAllocation(ClusterState clusterState,
 String reason,
 Consumer<RoutingAllocation> routingAllocationConsumer)

Computes the next step towards a fully allocated and balanced cluster and records this step in the routing table of the returned state. Should be called after every change to the cluster that affects the routing table and/or the balance of shards.

This method is expensive in larger clusters. Wherever possible you should invoke this method asynchronously using RerouteService.reroute(java.lang.String, org.elasticsearch.common.Priority, org.elasticsearch.action.ActionListener<org.elasticsearch.cluster.ClusterState>) to batch up invocations rather than calling the method directly. The node's reroute service is typically obtained from ClusterService.getRerouteService().

Returns:

an updated cluster state, or the same instance that was passed as an argument if no changes were made.

getHealthStatus

public static ClusterHealthStatus getHealthStatus(ClusterState clusterState)

currentNanoTime

protected long currentNanoTime()

override this to control time based decisions during allocation

cleanCaches

public void cleanCaches()

getNumberOfInFlightFetches

public int getNumberOfInFlightFetches()

explainShardAllocation

public ShardAllocationDecision explainShardAllocation(ShardRouting shardRouting,
 RoutingAllocation allocation)