class LeastShardAllocationStrategy extends ShardAllocationStrategy with Serializable
The default implementation of ShardCoordinator.LeastShardAllocationStrategy
allocates new shards to the ShardRegion
with least number of previously allocated shards.
It picks shards for rebalancing handoff from the ShardRegion
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. There is a configurable threshold of how large the difference
must be to begin the rebalancing. The number of ongoing rebalancing processes can be limited.
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- ShardCoordinator.scala
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- This member is added by an implicit conversion from LeastShardAllocationStrategy to any2stringadd[LeastShardAllocationStrategy] performed by method any2stringadd in scala.Predef.
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def
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def
allocateShard(requester: ActorRef, shardId: ShardId, currentShardAllocations: Map[ActorRef, IndexedSeq[ShardId]]): Future[ActorRef]
Invoked when the location of a new shard is to be decided.
Invoked when the location of a new shard is to be decided.
- requester
actor reference to the ShardRegion that requested the location of the shard, can be returned if preference should be given to the node where the shard was first accessed
- shardId
the id of the shard to allocate
- currentShardAllocations
all actor refs to
ShardRegion
and their current allocated shards, in the order they were allocated- returns
a
Future
of the actor ref of the ShardRegion that is to be responsible for the shard, must be one of the references included in thecurrentShardAllocations
parameter
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- LeastShardAllocationStrategy → ShardAllocationStrategy
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def
ensuring(cond: (LeastShardAllocationStrategy) ⇒ Boolean, msg: ⇒ Any): LeastShardAllocationStrategy
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- This member is added by an implicit conversion from LeastShardAllocationStrategy to Ensuring[LeastShardAllocationStrategy] performed by method Ensuring in scala.Predef.
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def
ensuring(cond: (LeastShardAllocationStrategy) ⇒ Boolean): LeastShardAllocationStrategy
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- This member is added by an implicit conversion from LeastShardAllocationStrategy to Ensuring[LeastShardAllocationStrategy] performed by method Ensuring in scala.Predef.
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def
ensuring(cond: Boolean, msg: ⇒ Any): LeastShardAllocationStrategy
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- This member is added by an implicit conversion from LeastShardAllocationStrategy to Ensuring[LeastShardAllocationStrategy] performed by method Ensuring in scala.Predef.
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def
ensuring(cond: Boolean): LeastShardAllocationStrategy
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- This member is added by an implicit conversion from LeastShardAllocationStrategy to Ensuring[LeastShardAllocationStrategy] performed by method Ensuring in scala.Predef.
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def
formatted(fmtstr: String): String
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- This member is added by an implicit conversion from LeastShardAllocationStrategy to StringFormat[LeastShardAllocationStrategy] performed by method StringFormat in scala.Predef.
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notifyAll(): Unit
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def
rebalance(currentShardAllocations: Map[ActorRef, IndexedSeq[ShardId]], rebalanceInProgress: Set[ShardId]): Future[Set[ShardId]]
Invoked periodically to decide which shards to rebalance to another location.
Invoked periodically to decide which shards to rebalance to another location.
- currentShardAllocations
all actor refs to
ShardRegion
and 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
- returns
a
Future
of the shards to be migrated, may be empty to skip rebalance in this round
- Definition Classes
- LeastShardAllocationStrategy → ShardAllocationStrategy
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final
def
synchronized[T0](arg0: ⇒ T0): T0
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toString(): String
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def
→[B](y: B): (LeastShardAllocationStrategy, B)
- Implicit
- This member is added by an implicit conversion from LeastShardAllocationStrategy to ArrowAssoc[LeastShardAllocationStrategy] performed by method ArrowAssoc in scala.Predef.
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- ArrowAssoc