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GridGain™ 2.1.0
Java API Specification
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org.gridgain.grid.spi.loadbalancing.adaptive
Class GridAdaptiveLoadBalancingSpi

java.lang.Object
  extended by org.gridgain.grid.spi.GridSpiAdapter
      extended by org.gridgain.grid.spi.loadbalancing.adaptive.GridAdaptiveLoadBalancingSpi
All Implemented Interfaces:
GridSpi, GridSpiManagementMBean, GridAdaptiveLoadBalancingSpiMBean, GridLoadBalancingSpi
@GridSpiInfo(author="GridGain Systems",
             url="www.gridgain.org",
             email="support@gridgain.com",
             version="x.x")
@GridSpiMultipleInstancesSupport(value=true)
public class GridAdaptiveLoadBalancingSpi
extends GridSpiAdapter
implements GridLoadBalancingSpi, GridAdaptiveLoadBalancingSpiMBean

Load balancing SPI that adapts to overall node performance. It proportionally distributes more jobs to more performant nodes based on a pluggable and dynamic node load probing.

Adaptive Node Probe

This SPI comes with pluggable algorithm to calculate a node load at any given point of time. The algorithm is defined by GridAdaptiveLoadProbe interface and user is free to provide custom implementations. By default GridAdaptiveCpuLoadProbe implementation is used which distributes jobs to nodes based on average CPU load on every node.

The following load probes are available with the product:

Note that if GridAdaptiveLoadProbe.getLoad(GridNode, int) returns a value of 0, then implementation will assume that load value is simply not available and will try to calculate an average of load values for other nodes. If such average cannot be obtained (all node load values are 0), then a value of 1 will be used.

When working with node metrics, take into account that all averages are calculated over metrics history size defined by GridConfiguration.getMetricsExpireTime() and GridConfiguration.getMetricsHistorySize() grid configuration parameters. Generally the larger these configuration parameter values are, the more precise the metrics are. You should tune these values based on the level of accuracy needed vs. the additional memory that would be required for storing metrics.

You should also keep in mind that metrics for remote nodes are delayed (usually by the heartbeat frequency). So if it is acceptable in your environment, set the heartbeat frequency to be more inline with job execution time. Generally, the more often heartbeats between nodes are exchanged, the more precise the metrics are. However, you should keep in mind that if heartbeats are exchanged too often then it may create unnecessary traffic in the network. Heartbeats (or metrics update frequency) can be configured via underlying GridDiscoverySpi used in your grid.

Here is an example of how probing can be implemented to use number of active and waiting jobs as probing mechanism: 

 public class FooBarLoadProbe implements GridAdaptiveLoadProbe {
     // Flag indicating whether to use average value or current.
     private int useAvg = true;

     public FooBarLoadProbe(boolean useAvg) {
         this.useAvg = useAvg;
     }

     // Calculate load based on number of active and waiting jobs.
     public double getLoad(GridNode node, int jobsSentSinceLastUpdate) {
         GridNodeMetrics metrics = node.getMetrics();

         if (useAvg == true) {
             double load = metrics.getAverageActiveJobs() + metrics.getAverageWaitingJobs();

             if (load > 0) {
                 return load;
             }
         }

         return metrics.getCurrentActiveJobs() + metrics.getCurrentWaitingJobs();
     }
 }

Which Node Probe To Use

There is no correct answer here. Every single node probe will work better or worse in different environments. CPU load probe (default option) is the safest approach to start with as it simply attempts to utilize every CPU on the grid to the maximum. However, you should experiment with other probes by executing load tests in your environment and observing which probe gives you best performance and load balancing.

Task Coding Example

If you are using GridTaskSplitAdapter then load balancing logic is transparent to your code and is handled automatically by the adapter. Here is an example of how your task will look: 
 public class MyFooBarTask extends GridTaskSplitAdapter<Object, Object> {
    @Override
    protected Collection<? extends GridJob> split(int gridSize, Object arg) throws GridException {
        List<MyFooBarJob> jobs = new ArrayList<MyFooBarJob>(gridSize);

        for (int i = 0; i < gridSize; i++) {
            jobs.add(new MyFooBarJob(arg));
        }

        // Node assignment via load balancer
        // happens automatically.
        return jobs;
    }
    ...
 }
If you need more fine-grained control over how some jobs within task get mapped to a node and use affinity load balancing for some other jobs within task, then you should use GridTaskAdapter. Here is an example of how your task will look. Note that in this case we manually inject load balancer and use it to pick the best node. Doing it in such way would allow user to map some jobs manually and for others use load balancer. 
 public class MyFooBarTask extends GridTaskAdapter<String, String> {
    // Inject load balancer.
    @GridLoadBalancerResource
    GridLoadBalancer balancer;

    // Map jobs to grid nodes.
    public Map<? extends GridJob, GridNode> map(List<GridNode> subgrid, String arg) throws GridException {
        Map<MyFooBarJob, GridNode> jobs = new HashMap<MyFooBarJob, GridNode>(subgrid.size());

        // In more complex cases, you can actually do
        // more complicated assignments of jobs to nodes.
        for (int i = 0; i < subgrid.size(); i++) {
            // Pick the next best balanced node for the job.
            jobs.put(new MyFooBarJob(arg), balancer.getBalancedNode())
        }

        return jobs;
    }

    // Aggregate results into one compound result.
    public String reduce(List<GridJobResult> results) throws GridException {
        // For the purpose of this example we simply
        // concatenate string representation of every
        // job result
        StringBuilder buf = new StringBuilder();

        for (GridJobResult res : results) {
            // Append string representation of result
            // returned by every job.
            buf.append(res.getData().toString());
        }

        return buf.toString();
    }
 }

Configuration

In order to use this load balancer, you should configure your grid instance to use GridJobsLoadBalancingSpi either from Spring XML file or directly. The following configuration parameters are supported:

Mandatory

This SPI has no mandatory configuration parameters.

Optional

This SPI has the following optional configuration parameters:

Below is Java configuration example: 

 GridAdaptiveLoadBalancingSpi spi = new GridAdaptiveLoadBalancingSpi();

 // Configure probe to use latest job execution time vs. average.
 GridAdaptiveProcessingTimeLoadProbe probe = new GridAdaptiveProcessingTimeLoadProbe(false);

 spi.setLoadProbe(probe);

 GridConfigurationAdapter cfg = new GridConfigurationAdapter();

 // Override default load balancing SPI.
 cfg.setLoadBalancingSpi(spi);

 // Start grid.
 GridFactory.start(cfg);
Here is how you can configure GridJobsLoadBalancingSpi using Spring XML configuration: 
 <property name="loadBalancingSpi">
     <bean class="org.gridgain.grid.spi.loadbalancing.adaptive.GridAdaptiveLoadBalancingSpi">
         <property name="loadProbe">
             <bean class="org.gridgain.grid.spi.loadbalancing.adaptive.GridAdaptiveProcessingTimeLoadProbe">
                 <constructor-arg value="false"/>
             </bean>
         </property>
     </bean>
 </property>


For information about Spring framework visit www.springframework.org



See Also:

  Documentation
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  Online Forums
  Issue Tracking

Author:   2005-2008 Copyright © GridGain Systems. All Rights Reserved. ver. 2.1.0

 

Constructor Summary
GridAdaptiveLoadBalancingSpi()
           
 
Method Summary
 GridNode getBalancedNode(GridTaskSession ses, List<GridNode> top, GridJob job)
          Gets balanced node for specified job within given task session.
 String getLoadProbeFormatted()
          Gets text description of current load probing implementation used.
 void onContextDestroyed()
          Callback invoked prior to stopping grid before SPI context is destroyed. Once this method is complete, grid will begin shutdown sequence. Use this callback for de-initialization logic that may involve SPI context. Note that invoking SPI context after this callback is complete is considered illegal and may produce unknown results.

If GridSpiAdapter is used for SPI implementation, then it will replace actual context with dummy no-op context which is usually good-enough since grid is about to shut down.
 void onContextInitialized(GridSpiContext spiCtx)
          Callback invoked when SPI context is initialized. SPI implementation may store SPI context for future access.

This method is invoked after GridSpi.spiStart(String) method is completed, so SPI should be fully functional at this point. Use this method for post-start initialization, such as subscribing a discovery listener, sending a message to remote node, etc...
 void setLoadProbe(GridAdaptiveLoadProbe probe)
          Sets implementation of node load probe.
 void spiStart(String gridName)
          This method is called to start SPI.
 void spiStop()
          This method is called to stop SPI.
 String toString()
          
 
Methods inherited from class org.gridgain.grid.spi.GridSpiAdapter
assertParameter, configInfo, createSpiAttributeName, getAuthor, getConsistentAttributeNames, getGridGainHome, getLocalNodeId, getName, getNodeAttributes, getSpiContext, getStartTimestamp, getStartTimestampFormatted, getUpTime, getUpTimeFormatted, getVendorEmail, getVendorUrl, getVersion, registerMBean, setName, setSpiContext, startInfo, startStopwatch, stopInfo, unregisterMBean
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 
Methods inherited from interface org.gridgain.grid.spi.GridSpi
getName, getNodeAttributes
 
Methods inherited from interface org.gridgain.grid.spi.GridSpiManagementMBean
getAuthor, getGridGainHome, getLocalNodeId, getName, getStartTimestamp, getStartTimestampFormatted, getUpTime, getUpTimeFormatted, getVendorEmail, getVendorUrl, getVersion
 

Constructor Detail

GridAdaptiveLoadBalancingSpi

public GridAdaptiveLoadBalancingSpi()
Method Detail

getLoadProbeFormatted

public String getLoadProbeFormatted()
Gets text description of current load probing implementation used.

Specified by:
getLoadProbeFormatted in interface GridAdaptiveLoadBalancingSpiMBean
Returns:
Text description of current load probing implementation used.

setLoadProbe

@GridSpiConfiguration(optional=true)
public void setLoadProbe(GridAdaptiveLoadProbe probe)
Sets implementation of node load probe. By default GridAdaptiveProcessingTimeLoadProbe is used which proportionally distributes load based on the average job execution time on every node.

Parameters:
probe - Implementation of node load probe

spiStart

public void spiStart(@Nullable
                     String gridName)
              throws GridSpiException
This method is called to start SPI. After this method returns successfully kernel assumes that SPI is fully operational.

Specified by:
spiStart in interface GridSpi
Throws:
GridSpiException - Throws in case of any error during SPI start.
Parameters:
gridName - Name of grid instance this SPI is being started for (null for default grid).

spiStop

public void spiStop()
             throws GridSpiException
This method is called to stop SPI. After this method returns kernel assumes that this SPI is finished and all resources acquired by it are released. Note that this method can be called at any point including during recovery of failed start. It should make no assumptions on what state SPI will be in when this method is called.

Specified by:
spiStop in interface GridSpi
Throws:
GridSpiException - Thrown in case of any error during SPI stop.

onContextInitialized

public void onContextInitialized(GridSpiContext spiCtx)
                          throws GridSpiException
Callback invoked when SPI context is initialized. SPI implementation may store SPI context for future access.

This method is invoked after GridSpi.spiStart(String) method is completed, so SPI should be fully functional at this point. Use this method for post-start initialization, such as subscribing a discovery listener, sending a message to remote node, etc...

Specified by:
onContextInitialized in interface GridSpi
Overrides:
onContextInitialized in class GridSpiAdapter
Throws:
GridSpiException - If context initialization failed (grid will be stopped).
Parameters:
spiCtx - Spi context.

onContextDestroyed

public void onContextDestroyed()
Callback invoked prior to stopping grid before SPI context is destroyed. Once this method is complete, grid will begin shutdown sequence. Use this callback for de-initialization logic that may involve SPI context. Note that invoking SPI context after this callback is complete is considered illegal and may produce unknown results.

If GridSpiAdapter is used for SPI implementation, then it will replace actual context with dummy no-op context which is usually good-enough since grid is about to shut down.

Specified by:
onContextDestroyed in interface GridSpi
Overrides:
onContextDestroyed in class GridSpiAdapter

getBalancedNode

public GridNode getBalancedNode(GridTaskSession ses,
                                List<GridNode> top,
                                GridJob job)
                         throws GridException
Gets balanced node for specified job within given task session.

Specified by:
getBalancedNode in interface GridLoadBalancingSpi
Throws:
GridException - If failed to get next balanced node.
Parameters:
ses - Grid task session for currently executing task.
top - Topology of task nodes from which to pick the best balanced node for given job.
job - Job for which to pick the best balanced node.
Returns:
Best balanced node for the given job within given task session.

toString

public String toString()

Overrides:
toString in class Object
Overview  Package   Class  Use  Tree  Deprecated  Index  Help 
GridGain™ 2.1.0
Java API Specification
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SUMMARY: NESTED | FIELD | CONSTR | METHOD DETAIL: FIELD | CONSTR | METHOD
GridGain™ - Grid Computing Made Simple, ver. 2.1.0.19122008
2005-2008 Copyright © GridGain Systems. All Rights Reserved.