com.netflix.fenzo

Class TaskScheduler.Builder

java.lang.Object

com.netflix.fenzo.TaskScheduler.Builder

Enclosing class:

TaskScheduler

public static final class TaskScheduler.Builder
extends java.lang.Object

The Builder is how you construct a TaskScheduler object with particular characteristics. Chain its methods and then call build() to create a TaskScheduler.

See Also:

Wikipedia: Builder pattern

Constructor Summary

Constructors

Constructor and Description
Builder()

Method Summary

Modifier and Type	Method and Description
TaskScheduler	build() Creates a TaskScheduler based on the various builder methods you have chained.
TaskScheduler.Builder	disableShortfallEvaluation() Disable resource shortfall evaluation.
TaskScheduler.Builder	withAutoScaleByAttributeName(java.lang.String name) Call this method to indicate which host attribute you want your task scheduler to use in order to distinguish which hosts are in which autoscaling groups.
TaskScheduler.Builder	withAutoScaleDownBalancedByAttributeName(java.lang.String name) Call this method to tell the autoscaler to try to maintain a balance of host varieties when it scales down a cluster.
TaskScheduler.Builder	withAutoScalerCallback(Action1<AutoScaleAction> callback)
TaskScheduler.Builder	withAutoScalerMapHostnameAttributeName(java.lang.String name) Use the given host attribute name to determine the alternate hostname of virtual machine to use as an argument for an autoscaling action.
TaskScheduler.Builder	withAutoScaleRule(AutoScaleRule rule) Adds an autoscaling rule that governs the behavior by which this scheduler will autoscale hosts of a certain type.
TaskScheduler.Builder	withDelayAutoscaleDownBySecs(long delayAutoscaleDownBySecs) Delay the autoscale down actions to reduce unnecessary actions due to short periods of breach of scale down policy rules.
TaskScheduler.Builder	withDelayAutoscaleUpBySecs(long delayAutoscaleUpBySecs) Delay the autoscale up actions to reduce unnecessary actions due to short periods of breach of scale up policy rules.
TaskScheduler.Builder	withFitnessCalculator(VMTaskFitnessCalculator fitnessCalculator) Call this method to add a fitness calculator that your scheduler will use to compute the suitability of a particular host for a particular task.
TaskScheduler.Builder	withFitnessGoodEnoughFunction(Func1<java.lang.Double,java.lang.Boolean> f) Use the given function to determine if the fitness of a host for a task is good enough that the task scheduler should stop looking for a more fit host.
TaskScheduler.Builder	withInitialResAllocs(java.util.Map<java.lang.String,ResAllocs> resAllocs) Call this method to set the initial limitations on how many resources will be available to each task group.
TaskScheduler.Builder	withLeaseOfferExpirySecs(long leaseOfferExpirySecs) Call this method to set the expiration time for resource offers.
TaskScheduler.Builder	withLeaseRejectAction(Action1<VirtualMachineLease> leaseRejectAction) (Required) Call this method to establish a method that your task scheduler will call to notify you that it has rejected a resource offer.
TaskScheduler.Builder	withMaxOffersToReject(int maxOffersToReject) Call this method to set the maximum number of offers to reject within a time period equal to lease expiry seconds, set with leaseOfferExpirySecs().
TaskScheduler.Builder	withRejectAllExpiredOffers() Indicate that all offers older than the set expiry time must be rejected.
TaskScheduler.Builder	withSingleOfferPerVM(boolean b) Indicate that the cluster receives resource offers only once per VM (host).

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Builder

public Builder()

Method Detail

withLeaseRejectAction

public TaskScheduler.Builder withLeaseRejectAction(Action1<VirtualMachineLease> leaseRejectAction)

(Required) Call this method to establish a method that your task scheduler will call to notify you that it has rejected a resource offer. In this method, you should tell Mesos that you are declining the associated offer.

Parameters:

leaseRejectAction - the action to trigger when the task scheduler rejects a VM lease, with the lease being rejected as the only argument

Returns:

this same Builder, suitable for further chaining or to build the TaskScheduler

withLeaseOfferExpirySecs

public TaskScheduler.Builder withLeaseOfferExpirySecs(long leaseOfferExpirySecs)

Call this method to set the expiration time for resource offers. Your task scheduler will reject any offers that remain unused if this expiration period from the time of the offer expires. This ensures your scheduler will not hoard unuseful offers. The default is 120 seconds.

Parameters:

leaseOfferExpirySecs - the amount of time the scheduler will keep an unused lease available for a later-scheduled task before it considers the lease to have expired, in seconds

Returns:

this same Builder, suitable for further chaining or to build the TaskScheduler

withMaxOffersToReject

public TaskScheduler.Builder withMaxOffersToReject(int maxOffersToReject)

Call this method to set the maximum number of offers to reject within a time period equal to lease expiry seconds, set with leaseOfferExpirySecs(). Default is 4.

Parameters:

maxOffersToReject - Maximum number of offers to reject.

Returns:

this same Builder, suitable for further chaining or to build the TaskScheduler

withRejectAllExpiredOffers

public TaskScheduler.Builder withRejectAllExpiredOffers()

Indicate that all offers older than the set expiry time must be rejected. By default this is set to false. If false, Fenzo rejects a maximum number of offers set using withMaxOffersToReject(int) per each time period spanning the expiry time, set by withLeaseOfferExpirySecs(long).

Returns:

this same Builder, suitable for further chaining or to build the TaskScheduler

withFitnessCalculator

public TaskScheduler.Builder withFitnessCalculator(VMTaskFitnessCalculator fitnessCalculator)

Call this method to add a fitness calculator that your scheduler will use to compute the suitability of a particular host for a particular task. You can only add a single fitness calculator to a scheduler; if you attempt to add a second fitness calculator, it will override the first one.

Parameters:

fitnessCalculator - the fitness calculator you want this scheduler to use in its evaluations

Returns:

this same Builder, suitable for further chaining or to build the TaskScheduler

See Also:

Fitness Calculators

withAutoScaleByAttributeName

public TaskScheduler.Builder withAutoScaleByAttributeName(java.lang.String name)

Call this method to indicate which host attribute you want your task scheduler to use in order to distinguish which hosts are in which autoscaling groups. You must call this method before you call withAutoScaleRule(AutoScaleRule).

Parameters:

name - the name of the host attribute that defines which autoscaling group it is in

Returns:

this same Builder, suitable for further chaining or to build the TaskScheduler

See Also:

Autoscaling

withAutoScalerMapHostnameAttributeName

public TaskScheduler.Builder withAutoScalerMapHostnameAttributeName(java.lang.String name)

Use the given host attribute name to determine the alternate hostname of virtual machine to use as an argument for an autoscaling action.

In some circumstances (for instance with Amazon Web Services), the host name is not the correct identifier for the host in the context of an autoscaling action (for instance, in AWS, you need the EC2 instance identifier). If this is the case for your system, you need to implement a function that maps the host name to the identifier for the host in an autoscaling context so that Fenzo can perform autoscaling properly. You provide this function to the task manager by means of this builder method.

Parameters:

name - the attribute name to use as the alternate host identifier in an autoscaling context

Returns:

this same Builder, suitable for further chaining or to build the TaskScheduler

See Also:

Autoscaling

withAutoScaleDownBalancedByAttributeName

public TaskScheduler.Builder withAutoScaleDownBalancedByAttributeName(java.lang.String name)

Call this method to tell the autoscaler to try to maintain a balance of host varieties when it scales down a cluster. Pass the method a host attribute, and the autoscaler will attempt to scale down in such a way as to maintain a similar number of hosts with each value for that attribute.

Parameters:

name - the name of the attribute

Returns:

this same Builder, suitable for further chaining or to build the TaskScheduler

See Also:

Autoscaling

withFitnessGoodEnoughFunction

public TaskScheduler.Builder withFitnessGoodEnoughFunction(Func1<java.lang.Double,java.lang.Boolean> f)

Use the given function to determine if the fitness of a host for a task is good enough that the task scheduler should stop looking for a more fit host. Pass this method a function that takes a value between 0.0 (completely unfit) and 1.0 (perfectly fit) that describes the fitness of a particular host for a particular task, and decides, by returning a boolean value, whether that value is a "good enough" fit such that the task scheduler should go ahead and assign the task to the host. If you write this function to only return true for values at or near 1.0, the task scheduler will spend more time searching for a good fit; if you write the function to return true for lower values, the task scheduler will be able to find a host to assign the task to more quickly.

By default, if you do not build your task scheduler by passing a function into this method, the task scheduler will always search all of the available hosts for the best possible fit for every task.

Parameters:

f - a single-argument function that accepts a double parameter, representing the fitness, and returns a Boolean indicating whether the fitness is good enough to constitute a successful match between the host and task

Returns:

this same Builder, suitable for further chaining or to build the TaskScheduler

disableShortfallEvaluation

public TaskScheduler.Builder disableShortfallEvaluation()

Disable resource shortfall evaluation. The shortfall evaluation is performed when evaluating the autoscaling needs. This is useful for evaluating the actual resources needed to scale up by, for pending tasks, which may be greater than the number of resources scaled up by thresholds based scale up.

This evaluation can be computaionally expensive and/or may scale up aggressively, initially, to more resources than needed. The initial aggressive scale up is corrected later by scale down, which is triggered by scale down evaluation after a cool down period transpires.

Returns:

this same Builder, suitable for further chaining or to build the TaskScheduler

See Also:

Autoscaling

withInitialResAllocs

public TaskScheduler.Builder withInitialResAllocs(java.util.Map<java.lang.String,ResAllocs> resAllocs)

Call this method to set the initial limitations on how many resources will be available to each task group.

Parameters:

resAllocs - a Map with the task group name as keys and resource allocation limits as values

Returns:

this same Builder, suitable for further chaining or to build the TaskScheduler

See Also:

Resource Allocation Limits

withAutoScaleRule

public TaskScheduler.Builder withAutoScaleRule(AutoScaleRule rule)

Adds an autoscaling rule that governs the behavior by which this scheduler will autoscale hosts of a certain type. You can chain this method multiple times, adding a new autoscaling rule each time (one for each autoscale group).

Before you call this method you must first call withAutoScaleByAttributeName() to indicate which host attribute you are using to identify which hosts are in which autoscaling groups.

Parameters:

rule - the autoscaling rule to add

Returns:

this same Builder, suitable for further chaining or to build the TaskScheduler

Throws:

java.lang.IllegalArgumentException - if you have not properly initialized autoscaling or if your rule is poorly formed

See Also:

Autoscaling

withAutoScalerCallback

public TaskScheduler.Builder withAutoScalerCallback(Action1<AutoScaleAction> callback)

withDelayAutoscaleUpBySecs

public TaskScheduler.Builder withDelayAutoscaleUpBySecs(long delayAutoscaleUpBySecs)

Delay the autoscale up actions to reduce unnecessary actions due to short periods of breach of scale up policy rules. Such scale ups can be caused by, for example, the periodic offer rejections that result in offers coming back shortly. They can also be caused by certain environments where tasks are first scheduled to replace existing tasks.

The autoscaler takes the scale up action based on the latest scale up request value after the delay.

The default is 0 secs. Ideally, you should set this to be at least two times the larger of the two values:

• Delay between successive calls to TaskScheduler.scheduleOnce(List, List).
• Delay in get a rejected offer back from Mesos.

Parameters:

delayAutoscaleUpBySecs - Delay autoscale up actions by this many seconds.

Returns:

this same Builder, suitable for further chaining or to build the TaskScheduler

Throws:

java.lang.IllegalArgumentException - if you give negative number for delayAutoscalerbySecs.

See Also:

Autoscaling

withDelayAutoscaleDownBySecs

public TaskScheduler.Builder withDelayAutoscaleDownBySecs(long delayAutoscaleDownBySecs)

Delay the autoscale down actions to reduce unnecessary actions due to short periods of breach of scale down policy rules. Such scale downs can be caused by, for example, certain environments where existing tasks are removed before replacing them with new tasks.

The autoscaler takes the scale down action based on the latest scale down request value after the delay.

The default is 0 secs. Ideally, you should set this to be at least two times the delay before terminated tasks are replaced successfully.

Parameters:

delayAutoscaleDownBySecs - Delay autoscale down actions by this many seconds.

Returns:

this same Builder, suitable for further chaining or to build the TaskScheduler

Throws:

java.lang.IllegalArgumentException - if you give negative number for delayAutoscalerbySecs.

See Also:

Autoscaling

withSingleOfferPerVM

public TaskScheduler.Builder withSingleOfferPerVM(boolean b)

Indicate that the cluster receives resource offers only once per VM (host). Normally, Mesos sends resource offers multiple times, as resources free up on the host upon completion of various tasks. This method provides an experimental support for a mode where Fenzo can be made aware of the entire set of resources on hosts once, in a model similar to Amazon ECS. Fenzo internally keeps track of total versus used resources on the host based on tasks assigned and then later unassigned. No further resource offers are expected after the initial one.

Parameters:

b - True if only one resource offer is expected per host, false by default.

Returns:

this same Builder, suitable for further chaining or to build the TaskScheduler

build

public TaskScheduler build()

Creates a TaskScheduler based on the various builder methods you have chained.

Returns:

a TaskScheduler built according to the specifications you indicated