com.bigdata.rdf.sail.webapp.lbs.policy.ganglia

Class GangliaLBSPolicy

java.lang.Object

com.bigdata.rdf.sail.webapp.lbs.AbstractLBSPolicy

com.bigdata.rdf.sail.webapp.lbs.AbstractHostLBSPolicy

com.bigdata.rdf.sail.webapp.lbs.policy.ganglia.GangliaLBSPolicy

All Implemented Interfaces:

QuorumListener, IHALoadBalancerPolicy, IHAPolicyLifeCycle, Serializable

public class GangliaLBSPolicy
extends AbstractHostLBSPolicy

Stochastically proxy the request to the services based on their load.

Note: This IHALoadBalancerPolicy has a dependency on the GangliaPlugIn. The GangliaPlugIn must be setup to listen to the Ganglia protocol and build up an in-memory model of the load on each host. Ganglia MUST be reporting metrics for each host running an HAJournalServer instance. This can be achieved either using the gmond utility from the ganglia distribution or using the GangliaPlugIn.

Note: The actual performance metrics will be reported by a given ganglia daemon on some host depend on the ganglia implementation, ganglia configuration, and the host OS. Some key performance metrics may not be available on all hosts. For example, IO Wait is not available under OSX. The available performance metrics constraints the IHostScoringRules that you can utilize on a given cluster. You can monitor the available performance metrics by running the GangliaListener utility.

Note: The ganglia updates are not synchronized across a cluster. They pour in ever N seconds from each host. However, the hosts do not begin to report on the same N second boundary. All you know is that (on average) all hosts should have reported in within N seconds.

Author:

Bryan Thompson

See Also:

GangliaService.getDefaultHostReportOn(), GangliaListener.main(String[]), Ganglia Wiki (has a section on the defined metics and the platform where they are available), Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	GangliaLBSPolicy.InitParams Servlet init-param values understood by the GangliaLBSPolicy.

Field Summary

Fields inherited from class com.bigdata.rdf.sail.webapp.lbs.AbstractLBSPolicy

journalRef, serviceIDRef, serviceTableRef

Constructor Summary

Constructors

Constructor and Description
GangliaLBSPolicy()

Method Summary

Methods

Modifier and Type	Method and Description
void	destroy() Destroy the policy (stop any asynchronous processing, release any resources).
protected String	getDefaultScoringRule() Return the name of the IHostScoringRule that provides default value for the AbstractHostLBSPolicy.InitParams.HOST_SCORING_RULE configuration parameter.
protected Map<String,IHostMetrics>	getHostReportForKnownServices(IHostScoringRule scoringRule, ServiceScore[] serviceScores) Return a map from the known canonical hostnames (as self-reported by the services) of the joined services to the IHostMetricss for those hosts.
void	init(javax.servlet.ServletConfig servletConfig, IIndexManager indexManager) Initialize the policy.
protected void	toString(StringBuilder sb) Extension hook for AbstractLBSPolicy.toString() - implementation MUST NOT block.

Methods inherited from class com.bigdata.rdf.sail.webapp.lbs.AbstractHostLBSPolicy

conditionallyForwardReadRequest, conditionallyUpdateServiceTable, getHostDiscoveryDelay, getReaderURI, setLocalForwardThreshold, updateHostTable, updateServiceTable

Methods inherited from class com.bigdata.rdf.sail.webapp.lbs.AbstractLBSPolicy

getJournal, getLeaderURI, getLocalServiceScore, getServiceScoreForHostname, notify, service, toString

Methods inherited from class java.lang.Object

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

Constructor Detail

GangliaLBSPolicy

public GangliaLBSPolicy()

Method Detail

toString

protected void toString(StringBuilder sb)

Description copied from class: AbstractLBSPolicy

Extension hook for AbstractLBSPolicy.toString() - implementation MUST NOT block.

Overrides:

toString in class AbstractHostLBSPolicy

Parameters:

sb - Buffer where you can write additional state.

init

public void init(javax.servlet.ServletConfig servletConfig,
        IIndexManager indexManager)
          throws javax.servlet.ServletException

Description copied from interface: IHAPolicyLifeCycle

Initialize the policy.

Specified by:

init in interface IHAPolicyLifeCycle

Overrides:

init in class AbstractHostLBSPolicy

Throws:

javax.servlet.ServletException

destroy

public void destroy()

Description copied from interface: IHAPolicyLifeCycle

Destroy the policy (stop any asynchronous processing, release any resources).

Specified by:

destroy in interface IHAPolicyLifeCycle

Overrides:

destroy in class AbstractHostLBSPolicy

getHostReportForKnownServices

protected Map<String,IHostMetrics> getHostReportForKnownServices(IHostScoringRule scoringRule,
                                                     ServiceScore[] serviceScores)

Return a map from the known canonical hostnames (as self-reported by the services) of the joined services to the IHostMetricss for those hosts.

This implementation queries the in-memory model of the cluster that is built up and maintained by the integrated GangliaService.

Specified by:

getHostReportForKnownServices in class AbstractHostLBSPolicy

Parameters:

scoringRule - The IHostScoringRule to be applied.

serviceScores - The set of known services.

Returns:

The map. TODO If there is more than one service on the same host, then we will have one record per host, not per service. This means that we can not support JVM specific metrics, such as GC time. This could be fixed if the map was indexed by Service UUID and the host metrics were combined into the map once for each service.

getDefaultScoringRule

protected String getDefaultScoringRule()

Description copied from class: AbstractHostLBSPolicy

Return the name of the IHostScoringRule that provides default value for the AbstractHostLBSPolicy.InitParams.HOST_SCORING_RULE configuration parameter.

Note: The policy needs to be specific to the LBS implementation since the names of the host metrics depend on the system that is being used to collect and report them.

Specified by:

getDefaultScoringRule in class AbstractHostLBSPolicy