Class BalancedShardsAllocator

  • All Implemented Interfaces:

    public class BalancedShardsAllocator
    extends java.lang.Object
    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.

    • Field Detail


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

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

        public static final Setting<java.lang.Float> THRESHOLD_SETTING
    • Constructor Detail

      • BalancedShardsAllocator

        public BalancedShardsAllocator​(Settings settings)
    • 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
        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.