c

akka.routing

TailChoppingRoutingLogic

final case class TailChoppingRoutingLogic(scheduler: Scheduler, within: FiniteDuration, interval: FiniteDuration, context: ExecutionContext) extends RoutingLogic with Product with Serializable

As each message is sent to the router, the routees are randomly ordered. The message is sent to the first routee. If no response is received before the interval has passed, the same message is sent to the next routee. This process repeats until either a response is received from some routee, the routees in the pool are exhausted, or the within duration has passed since the first send. If no routee sends a response in time, a akka.actor.Status.Failure wrapping a akka.pattern.AskTimeoutException is sent to the sender.

The goal of this routing algorithm is to decrease tail latencies ("chop off the tail latency") in situations where multiple routees can perform the same piece of work, and where a routee may occasionally respond more slowly than expected. In this case, sending the same work request (also known as a "backup request") to another actor results in decreased response time - because it's less probable that multiple actors are under heavy load simultaneously. This technique is explained in depth in Jeff Dean's presentation on Achieving Rapid Response Times in Large Online Services.

scheduler

schedules sending messages to routees

within

expecting at least one reply within this duration, otherwise it will reply with akka.pattern.AskTimeoutException in a akka.actor.Status.Failure

interval

duration after which the message will be sent to the next routee

context

execution context used by scheduler

Annotations
@SerialVersionUID()
Source
TailChopping.scala
Linear Supertypes
Serializable, Serializable, Product, Equals, RoutingLogic, NoSerializationVerificationNeeded, AnyRef, Any
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Inherited
  1. TailChoppingRoutingLogic
  2. Serializable
  3. Serializable
  4. Product
  5. Equals
  6. RoutingLogic
  7. NoSerializationVerificationNeeded
  8. AnyRef
  9. Any
Implicitly
  1. by any2stringadd
  2. by StringFormat
  3. by Ensuring
  4. by ArrowAssoc
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Visibility
  1. Public
  2. All

Instance Constructors

  1. new TailChoppingRoutingLogic(scheduler: Scheduler, within: FiniteDuration, interval: FiniteDuration, context: ExecutionContext)

    scheduler

    schedules sending messages to routees

    within

    expecting at least one reply within this duration, otherwise it will reply with akka.pattern.AskTimeoutException in a akka.actor.Status.Failure

    interval

    duration after which the message will be sent to the next routee

    context

    execution context used by scheduler

Value Members

  1. val context: ExecutionContext
  2. val interval: FiniteDuration
  3. val scheduler: Scheduler
  4. def select(message: Any, routees: IndexedSeq[Routee]): Routee

    Pick the destination for a given message.

    Pick the destination for a given message. Normally it picks one of the passed routees, but in the end it is up to the implementation to return whatever Routee to use for sending a specific message.

    When implemented from Java it can be good to know that routees.apply(index) can be used to get an element from the IndexedSeq.

    Definition Classes
    TailChoppingRoutingLogic → RoutingLogic
  5. val within: FiniteDuration