Package org.apache.pekko.cluster.sharding

Class ShardCoordinator$

java.lang.Object

org.apache.pekko.cluster.sharding.ShardCoordinator$

public class ShardCoordinator$
extends java.lang.Object

See Also:

ClusterSharding extension

Field Summary

Fields

Modifier and Type	Field	Description
static ShardCoordinator$	MODULE$	Static reference to the singleton instance of this Scala object.

Constructor Summary

Constructors

Constructor	Description
ShardCoordinator$()

Method Summary

Modifier and Type	Method	Description
ShardCoordinator.ShardAllocationStrategy	leastShardAllocationStrategy(int absoluteLimit, double relativeLimit)	Java API: ShardAllocationStrategy that allocates new shards to the ShardRegion (node) with least number of previously allocated shards.

Methods inherited from class java.lang.Object

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

Field Detail

MODULE$

public static final ShardCoordinator$ MODULE$

Static reference to the singleton instance of this Scala object.

Constructor Detail

ShardCoordinator$

public ShardCoordinator$()

Method Detail

leastShardAllocationStrategy

public ShardCoordinator.ShardAllocationStrategy leastShardAllocationStrategy(int absoluteLimit,
                                                                             double relativeLimit)

Java API: ShardAllocationStrategy that 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 LeastShardAllocationStrategy picks shards for rebalancing from the ShardRegions with most number of previously allocated shards. They will then be allocated to the ShardRegion with 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.

Parameters:

absoluteLimit - the maximum number of shards that will be rebalanced in one rebalance round

relativeLimit - fraction (< 1.0) of total number of (known) shards that will be rebalanced in one rebalance round