org.apache.hadoop.yarn.server.api
Class AuxiliaryService

java.lang.Object
  org.apache.hadoop.service.AbstractService
      org.apache.hadoop.yarn.server.api.AuxiliaryService

All Implemented Interfaces:

Closeable, org.apache.hadoop.service.Service

@InterfaceAudience.Public
@InterfaceStability.Evolving
public abstract class AuxiliaryService
extends org.apache.hadoop.service.AbstractService

A generic service that will be started by the NodeManager. This is a service that administrators have to configure on each node by setting YarnConfiguration.NM_AUX_SERVICES.

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.hadoop.service.Service

org.apache.hadoop.service.Service.STATE

Constructor Summary

protected

AuxiliaryService(String name)

Method Summary

abstract ByteBuffer	getMetaData() Retrieve meta-data for this AuxiliaryService.
protected org.apache.hadoop.fs.Path	getRecoveryPath() Get the path specific to this auxiliary service to use for recovery.
abstract void	initializeApplication(ApplicationInitializationContext initAppContext) A new application is started on this NodeManager.
void	initializeContainer(ContainerInitializationContext initContainerContext) A new container is started on this NodeManager.
void	setRecoveryPath(org.apache.hadoop.fs.Path recoveryPath) Set the path for this auxiliary service to use for storing state that will be used during recovery.
abstract void	stopApplication(ApplicationTerminationContext stopAppContext) An application is finishing on this NodeManager.
void	stopContainer(ContainerTerminationContext stopContainerContext) A container is finishing on this NodeManager.

Methods inherited from class org.apache.hadoop.service.AbstractService

close, getBlockers, getConfig, getFailureCause, getFailureState, getLifecycleHistory, getName, getServiceState, getStartTime, init, isInState, noteFailure, putBlocker, registerGlobalListener, registerServiceListener, removeBlocker, serviceInit, serviceStart, serviceStop, setConfig, start, stop, toString, unregisterGlobalListener, unregisterServiceListener, waitForServiceToStop

Methods inherited from class java.lang.Object

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

Constructor Detail

AuxiliaryService

protected AuxiliaryService(String name)

Method Detail

getRecoveryPath

protected org.apache.hadoop.fs.Path getRecoveryPath()

Get the path specific to this auxiliary service to use for recovery.

Returns:

state storage path or null if recovery is not enabled

initializeApplication

public abstract void initializeApplication(ApplicationInitializationContext initAppContext)

A new application is started on this NodeManager. This is a signal to this AuxiliaryService about the application initialization.

Parameters:

initAppContext - context for the application's initialization

stopApplication

public abstract void stopApplication(ApplicationTerminationContext stopAppContext)

An application is finishing on this NodeManager. This is a signal to this AuxiliaryService about the same.

Parameters:

stopAppContext - context for the application termination

getMetaData

public abstract ByteBuffer getMetaData()

Retrieve meta-data for this AuxiliaryService. Applications using this AuxiliaryService SHOULD know the format of the meta-data - ideally each service should provide a method to parse out the information to the applications. One example of meta-data is contact information so that applications can access the service remotely. This will only be called after the service's AbstractService.start() method has finished. the result may be cached.

The information is passed along to applications via StartContainersResponse.getAllServicesMetaData() that is returned by ContainerManagementProtocol.startContainers(StartContainersRequest)

Returns:

meta-data for this service that should be made available to applications.

initializeContainer

public void initializeContainer(ContainerInitializationContext initContainerContext)

A new container is started on this NodeManager. This is a signal to this AuxiliaryService about the container initialization. This method is called when the NodeManager receives the container launch command from the ApplicationMaster and before the container process is launched.

Parameters:

initContainerContext - context for the container's initialization

stopContainer

public void stopContainer(ContainerTerminationContext stopContainerContext)

A container is finishing on this NodeManager. This is a signal to this AuxiliaryService about the same.

Parameters:

stopContainerContext - context for the container termination

setRecoveryPath

public void setRecoveryPath(org.apache.hadoop.fs.Path recoveryPath)

Set the path for this auxiliary service to use for storing state that will be used during recovery.

Parameters:

recoveryPath - where recoverable state should be stored