case class DefaultResizer(lowerBound: Int = 1, upperBound: Int = 10, pressureThreshold: Int = 1, rampupRate: Double = 0.2, backoffThreshold: Double = 0.3, backoffRate: Double = 0.1, messagesPerResize: Int = 10) extends Resizer with Product with Serializable

Implementation of Resizer that adjust the Pool based on specified thresholds.

lowerBound

The fewest number of routees the router should ever have.

upperBound

The most number of routees the router should ever have. Must be greater than or equal to lowerBound.

pressureThreshold

Threshold to evaluate if routee is considered to be busy (under pressure). Implementation depends on this value (default is 1).

  • 0: number of routees currently processing a message.
  • 1: number of routees currently processing a message has some messages in mailbox.
  • > 1: number of routees with at least the configured pressureThreshold messages in their mailbox. Note that estimating mailbox size of default UnboundedMailbox is O(N) operation.
rampupRate

Percentage to increase capacity whenever all routees are busy. For example, 0.2 would increase 20% (rounded up), i.e. if current capacity is 6 it will request an increase of 2 more routees.

backoffThreshold

Minimum fraction of busy routees before backing off. For example, if this is 0.3, then we'll remove some routees only when less than 30% of routees are busy, i.e. if current capacity is 10 and 3 are busy then the capacity is unchanged, but if 2 or less are busy the capacity is decreased. Use 0.0 or negative to avoid removal of routees.

backoffRate

Fraction of routees to be removed when the resizer reaches the backoffThreshold. For example, 0.1 would decrease 10% (rounded up), i.e. if current capacity is 9 it will request an decrease of 1 routee.

messagesPerResize

Number of messages between resize operation. Use 1 to resize before each message.

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@SerialVersionUID()
Source
Resizer.scala
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Serializable, Product, Equals, Resizer, AnyRef, Any
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Instance Constructors

  1. new DefaultResizer(lower: Int, upper: Int)

    Java API constructor for default values except bounds.

  2. new DefaultResizer(lowerBound: Int = 1, upperBound: Int = 10, pressureThreshold: Int = 1, rampupRate: Double = 0.2, backoffThreshold: Double = 0.3, backoffRate: Double = 0.1, messagesPerResize: Int = 10)

    lowerBound

    The fewest number of routees the router should ever have.

    upperBound

    The most number of routees the router should ever have. Must be greater than or equal to lowerBound.

    pressureThreshold

    Threshold to evaluate if routee is considered to be busy (under pressure). Implementation depends on this value (default is 1).

    • 0: number of routees currently processing a message.
    • 1: number of routees currently processing a message has some messages in mailbox.
    • > 1: number of routees with at least the configured pressureThreshold messages in their mailbox. Note that estimating mailbox size of default UnboundedMailbox is O(N) operation.
    rampupRate

    Percentage to increase capacity whenever all routees are busy. For example, 0.2 would increase 20% (rounded up), i.e. if current capacity is 6 it will request an increase of 2 more routees.

    backoffThreshold

    Minimum fraction of busy routees before backing off. For example, if this is 0.3, then we'll remove some routees only when less than 30% of routees are busy, i.e. if current capacity is 10 and 3 are busy then the capacity is unchanged, but if 2 or less are busy the capacity is decreased. Use 0.0 or negative to avoid removal of routees.

    backoffRate

    Fraction of routees to be removed when the resizer reaches the backoffThreshold. For example, 0.1 would decrease 10% (rounded up), i.e. if current capacity is 9 it will request an decrease of 1 routee.

    messagesPerResize

    Number of messages between resize operation. Use 1 to resize before each message.

Value Members

  1. def backoff(pressure: Int, capacity: Int): Int

    Computes a proposed negative (or zero) capacity delta using the configured backoffThreshold and backoffRate

    Computes a proposed negative (or zero) capacity delta using the configured backoffThreshold and backoffRate

    pressure

    the current number of busy routees

    capacity

    the current number of total routees

    returns

    proposed decrease in capacity (as a negative number)

  2. val backoffRate: Double
  3. val backoffThreshold: Double
  4. def capacity(routees: IndexedSeq[Routee]): Int

    Returns the overall desired change in resizer capacity.

    Returns the overall desired change in resizer capacity. Positive value will add routees to the resizer. Negative value will remove routees from the resizer.

    routees

    The current actor in the resizer

    returns

    the number of routees by which the resizer should be adjusted (positive, negative or zero)

  5. def filter(pressure: Int, capacity: Int): Int

    This method can be used to smooth the capacity delta by considering the current pressure and current capacity.

    This method can be used to smooth the capacity delta by considering the current pressure and current capacity.

    pressure

    current number of busy routees

    capacity

    current number of routees

    returns

    proposed change in the capacity

  6. def isTimeForResize(messageCounter: Long): Boolean

    Is it time for resizing.

    Is it time for resizing. Typically implemented with modulo of nth message, but could be based on elapsed time or something else. The messageCounter starts with 0 for the initial resize and continues with 1 for the first message. Make sure to perform initial resize before first message (messageCounter == 0), because there is no guarantee that resize will be done when concurrent messages are in play.

    CAUTION: this method is invoked from the thread which tries to send a message to the pool, i.e. the ActorRef.!() method, hence it may be called concurrently.

    Definition Classes
    DefaultResizer → Resizer
  7. val lowerBound: Int
  8. val messagesPerResize: Int
  9. def pressure(routees: IndexedSeq[Routee]): Int

    Number of routees considered busy, or above 'pressure level'.

    Number of routees considered busy, or above 'pressure level'.

    Implementation depends on the value of pressureThreshold (default is 1).

    • 0: number of routees currently processing a message.
    • 1: number of routees currently processing a message has some messages in mailbox.
    • > 1: number of routees with at least the configured pressureThreshold messages in their mailbox. Note that estimating mailbox size of default UnboundedMailbox is O(N) operation.
    routees

    the current resizer of routees

    returns

    number of busy routees, between 0 and routees.size

  10. val pressureThreshold: Int
  11. def productElementNames: Iterator[String]
    Definition Classes
    Product
  12. def rampup(pressure: Int, capacity: Int): Int

    Computes a proposed positive (or zero) capacity delta using the configured rampupRate.

    Computes a proposed positive (or zero) capacity delta using the configured rampupRate.

    pressure

    the current number of busy routees

    capacity

    the current number of total routees

    returns

    proposed increase in capacity

  13. val rampupRate: Double
  14. def resize(currentRoutees: IndexedSeq[Routee]): Int

    Decide if the capacity of the router need to be changed.

    Decide if the capacity of the router need to be changed. Will be invoked when isTimeForResize returns true and no other resize is in progress.

    Return the number of routees to add or remove. Negative value will remove that number of routees. Positive value will add that number of routees. 0 will not change the routees.

    This method is invoked only in the context of the Router actor.

    Definition Classes
    DefaultResizer → Resizer
  15. val upperBound: Int