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
- 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
pressureThresholdmessages 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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Instance Constructors
-
new
DefaultResizer(lower: Int, upper: Int)
Java API constructor for default values except bounds.
-
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
pressureThresholdmessages 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
-
def
backoff(pressure: Int, capacity: Int): Int
Computes a proposed negative (or zero) capacity delta using the configured
backoffThresholdandbackoffRateComputes a proposed negative (or zero) capacity delta using the configured
backoffThresholdandbackoffRate- pressure
the current number of busy routees
- capacity
the current number of total routees
- returns
proposed decrease in capacity (as a negative number)
- val backoffRate: Double
- val backoffThreshold: Double
-
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)
-
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
-
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
- val lowerBound: Int
- val messagesPerResize: Int
-
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
pressureThresholdmessages 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
- val pressureThreshold: Int
-
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
- val rampupRate: Double
-
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
isTimeForResizereturns 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
- val upperBound: Int