- All Implemented Interfaces:
public class LeastShardAllocationStrategy extends AbstractLeastShardAllocationStrategyINTERNAL API: Use
ShardAllocationStrategythat allocates new shards to the
ShardRegion(node) with least number of previously allocated shards.
When a node is added to the cluster the shards on the existing nodes will be rebalanced to the new node. The
LeastShardAllocationStrategypicks shards for rebalancing from the
ShardRegions with most number of previously allocated shards. They will then be allocated to the
ShardRegionwith least number of previously allocated shards, i.e. new members in the cluster. The amount of shards to rebalance in each round can be limited to make it progress slower since rebalancing too many shards at the same time could result in additional load on the system. For example, causing many Event Sourced entites to be started at the same time.
It will not rebalance when there is already an ongoing rebalance in progress.
param: absoluteLimit the maximum number of shards that will be rebalanced in one rebalance round param: relativeLimit fraction (< 1.0) of total number of (known) shards that will be rebalanced in one rebalance round
Nested Class Summary
Nested classes/interfaces inherited from class akka.cluster.sharding.internal.AbstractLeastShardAllocationStrategy
AbstractLeastShardAllocationStrategy.RegionEntry, AbstractLeastShardAllocationStrategy.RegionEntry$, AbstractLeastShardAllocationStrategy.ShardSuitabilityOrdering$
Constructors Constructor Description
LeastShardAllocationStrategy(int absoluteLimit, double relativeLimit)
All Methods Instance Methods Concrete Methods Modifier and Type Method Description
rebalance(scala.collection.immutable.Map<ActorRef,scala.collection.immutable.IndexedSeq<java.lang.String>> currentShardAllocations, scala.collection.immutable.Set<java.lang.String> rebalanceInProgress)Invoked periodically to decide which shards to rebalance to another location.
Methods inherited from class akka.cluster.sharding.internal.AbstractLeastShardAllocationStrategy
allocateShard, clusterState, isAGoodTimeToRebalance, mostSuitableRegion, regionEntriesFor, selfMember, start
public scala.concurrent.Future<scala.collection.immutable.Set<java.lang.String>> rebalance(scala.collection.immutable.Map<ActorRef,scala.collection.immutable.IndexedSeq<java.lang.String>> currentShardAllocations, scala.collection.immutable.Set<java.lang.String> rebalanceInProgress)Description copied from interface:
ShardCoordinator.ShardAllocationStrategyInvoked periodically to decide which shards to rebalance to another location.
currentShardAllocations- all actor refs to
ShardRegionand their current allocated shards, in the order they were allocated
rebalanceInProgress- set of shards that are currently being rebalanced, i.e. you should not include these in the returned set
Futureof the shards to be migrated, may be empty to skip rebalance in this round
public java.lang.String toString()