Package hudson.model

Class LoadBalancer

java.lang.Object

hudson.model.LoadBalancer

All Implemented Interfaces:

ExtensionPoint

public abstract class LoadBalancer
extends Object
implements ExtensionPoint

Strategy that decides which Queue.Task gets run on which Executor.

Even though this is marked as ExtensionPoint, you do not register your implementation with @Extension. Instead, call Queue.setLoadBalancer(LoadBalancer) to install your implementation.

Since:

1.301

Author:

Kohsuke Kawaguchi

Nested Class Summary

Nested classes/interfaces inherited from interface hudson.ExtensionPoint

ExtensionPoint.LegacyInstancesAreScopedToHudson

Field Summary

Fields

Modifier and Type	Field	Description
static LoadBalancer	CONSISTENT_HASH	Uses a consistent hash for scheduling.
static LoadBalancer	DEFAULT	Deprecated. as of 1.377 The only implementation in the core now is the one based on consistent hash.

Constructor Summary

Constructors

Constructor	Description
LoadBalancer()

Method Summary

Modifier and Type	Method	Description
abstract MappingWorksheet.Mapping	map(Queue.Task task, MappingWorksheet worksheet)	Chooses the executor(s) to carry out the build for the given task.
protected LoadBalancer	sanitize()	Wraps this LoadBalancer into a decorator that tests the basic sanity of the implementation.

Methods inherited from class java.lang.Object

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

Field Detail

CONSISTENT_HASH

public static final LoadBalancer CONSISTENT_HASH

Uses a consistent hash for scheduling.

DEFAULT

@Deprecated
public static final LoadBalancer DEFAULT

Deprecated.

as of 1.377 The only implementation in the core now is the one based on consistent hash.

Traditional implementation of this.

Constructor Detail

LoadBalancer

public LoadBalancer()

Method Detail

map

@CheckForNull
public abstract MappingWorksheet.Mapping map(@NonNull
                                             Queue.Task task,
                                             MappingWorksheet worksheet)

Chooses the executor(s) to carry out the build for the given task.

This method is invoked from different threads, but the execution is serialized by the caller. The thread that invokes this method always holds a lock to Queue, so queue contents can be safely introspected from this method, if that information is necessary to make decisions.

Parameters:

task - The task whose execution is being considered. Never null.

worksheet - The work sheet that represents the matching that needs to be made. The job of this method is to determine which work units on this worksheet are executed on which executors (also on this worksheet.)

Returns:

Build up the mapping by using the given worksheet and return it. Return null if you don't want the task to be executed right now, in which case this method will be called some time later with the same task.

sanitize

protected LoadBalancer sanitize()

Wraps this LoadBalancer into a decorator that tests the basic sanity of the implementation. Only override this if you find some of the checks excessive, but beware that it's like driving without a seat belt.