org.gridgain.grid.spi.loadbalancing.weightedrandom

Class GridWeightedRandomLoadBalancingSpi

java.lang.Object

org.gridgain.grid.spi.GridSpiAdapter

org.gridgain.grid.spi.loadbalancing.weightedrandom.GridWeightedRandomLoadBalancingSpi

All Implemented Interfaces:

GridSpi, GridSpiManagementMBean, GridLoadBalancingSpi, GridWeightedRandomLoadBalancingSpiMBean

@GridSpiMultipleInstancesSupport(value=true)
@GridSpiConsistencyChecked(optional=true)
public class GridWeightedRandomLoadBalancingSpi
extends GridSpiAdapter
implements GridLoadBalancingSpi, GridWeightedRandomLoadBalancingSpiMBean

Load balancing SPI that picks a random node for job execution. Note that you can optionally assign weights to nodes, so nodes with larger weights will end up getting proportionally more jobs routed to them (see setNodeWeight(int) configuration property). By default all nodes get equal weight defined by DFLT_NODE_WEIGHT (value is 10).

Coding Example

If you are using GridComputeTaskSplitAdapter then load balancing logic is transparent to your code and is handled automatically by the adapter. Here is an example of how your task could look:

 public class MyFooBarTask extends GridComputeTaskSplitAdapter<Object, Object> {
    @Override
    protected Collection<? extends GridComputeJob> 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 GridComputeTaskAdapter. 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 GridComputeTaskAdapter<String, String> {
    // Inject load balancer.
    @GridLoadBalancerResource
    GridComputeLoadBalancer balancer;

    // Map jobs to grid nodes.
    public Map<? extends GridComputeJob, 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<GridComputeJobResult> results) throws GridException {
        // For the purpose of this example we simply
        // concatenate string representation of every
        // job result
        StringBuilder buf = new StringBuilder();

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

        return buf.string();
    }
 }
 

Configuration

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

Mandatory

This SPI has no mandatory configuration parameters.

Optional

The following configuration parameters are optional:

• Flag that indicates whether to use weight policy or simple random policy (see setUseWeights(boolean))
• Weight of this node (see setNodeWeight(int)). This parameter is ignored if setUseWeights(boolean) is set to false.

Below is Java configuration example:

 GridWeightedRandomLoadBalancingSpi = new GridWeightedLoadBalancingSpi();

 // Configure SPI to used weighted
 // random load balancing.
 spi.setUseWeights(true);

 // Set weight for the local node.
 spi.setWeight( *);

 GridConfiguration cfg = new GridConfiguration();

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

 // Starts grid.
 G.start(cfg);
 

Here is how you can configure GridRandomLoadBalancingSpi using Spring XML configuration:

 <property name="loadBalancingSpi">
     <bean class="org.gridgain.grid.spi.loadBalancing.weightedrandom.GridWeightedRandomLoadBalancingSpi">
         <property name="useWeights" value="true"/>
         <property name="nodeWeight" value="10"/>
     </bean>
 </property>
 

For information about Spring framework visit www.springframework.org

Field Summary

Fields

Modifier and Type	Field and Description
static int	DFLT_NODE_WEIGHT Default weight assigned to every node if explicit one is not provided (value is 10).
static String	NODE_WEIGHT_ATTR_NAME Name of node attribute used to indicate load weight of a node (value is "gridgain.node.weight.attr.name").

Constructor Summary

Constructors

Constructor and Description
GridWeightedRandomLoadBalancingSpi()

Method Summary

Methods

Modifier and Type	Method and Description
GridNode	getBalancedNode(GridComputeTaskSession ses, List<GridNode> top, GridComputeJob job) Gets balanced node for specified job within given task session.
protected List<String>	getConsistentAttributeNames() Returns back a list of attributes that should be consistent for this SPI.
Map<String,Object>	getNodeAttributes() This method is called before SPI starts (before method GridSpi.spiStart(String) is called).
int	getNodeWeight() Gets weight of this node.
boolean	isUseWeights() Checks whether node weights are considered when doing random load balancing.
protected void	onContextDestroyed0() Method to be called in the beginning of onContextDestroyed() method.
protected void	onContextInitialized0(GridSpiContext spiCtx) Method to be called in the end of onContextInitialized method.
void	setNodeWeight(int nodeWeight) Sets weight of this node.
void	setUseWeights(boolean isUseWeights) Sets a flag to indicate whether node weights should be checked when doing random load balancing.
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, checkConfigurationConsistency0, configInfo, createSpiAttributeName, getGridGainHome, getLocalNodeId, getName, getSpiContext, getStartTimestamp, getStartTimestampFormatted, getUpTime, getUpTimeFormatted, injectables, onContextDestroyed, onContextInitialized, registerMBean, setName, 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, onContextDestroyed, onContextInitialized

Methods inherited from interface org.gridgain.grid.spi.GridSpiManagementMBean

getGridGainHome, getLocalNodeId, getName, getStartTimestamp, getStartTimestampFormatted, getUpTime, getUpTimeFormatted

Field Detail

NODE_WEIGHT_ATTR_NAME

public static final String NODE_WEIGHT_ATTR_NAME

Name of node attribute used to indicate load weight of a node (value is "gridgain.node.weight.attr.name").

See Also:

GridNode.attributes(), Constant Field Values

DFLT_NODE_WEIGHT

public static final int DFLT_NODE_WEIGHT

Default weight assigned to every node if explicit one is not provided (value is 10).

See Also:

Constant Field Values

Constructor Detail

GridWeightedRandomLoadBalancingSpi

public GridWeightedRandomLoadBalancingSpi()

Method Detail

setUseWeights

@GridSpiConfiguration(optional=true)
public void setUseWeights(boolean isUseWeights)

Sets a flag to indicate whether node weights should be checked when doing random load balancing. Default value is false which means that node weights are disregarded for load balancing logic.

Parameters:

isUseWeights - If true then random load is distributed according to node weights.

isUseWeights

public boolean isUseWeights()

Checks whether node weights are considered when doing random load balancing.

Specified by:

isUseWeights in interface GridWeightedRandomLoadBalancingSpiMBean

Returns:

If true then random load is distributed according to node weights.

setNodeWeight

@GridSpiConfiguration(optional=true)
public void setNodeWeight(int nodeWeight)

Sets weight of this node. Nodes with more processing capacity should be assigned proportionally larger weight. Default value is DFLT_NODE_WEIGHT and is equal for all nodes.

Parameters:

nodeWeight - Weight of this node.

getNodeWeight

public int getNodeWeight()

Gets weight of this node.

Specified by:

getNodeWeight in interface GridWeightedRandomLoadBalancingSpiMBean

Returns:

Weight of this node.

getNodeAttributes

public Map<String,Object> getNodeAttributes()
                                     throws GridSpiException

This method is called before SPI starts (before method GridSpi.spiStart(String) is called). It allows SPI implementation to add attributes to a local node. Kernal collects these attributes from all SPI implementations loaded up and then passes it to discovery SPI so that they can be exchanged with other nodes.

Specified by:

getNodeAttributes in interface GridSpi

Overrides:

getNodeAttributes in class GridSpiAdapter

Returns:

Map of local node attributes this SPI wants to add.

Throws:

GridSpiException - Throws in case of any error.

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

Parameters:

gridName - Name of grid instance this SPI is being started for (null for default grid).

Throws:

GridSpiException - Throws in case of any error during SPI start.

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.

onContextInitialized0

protected void onContextInitialized0(GridSpiContext spiCtx)
                              throws GridSpiException

Method to be called in the end of onContextInitialized method.

Overrides:

onContextInitialized0 in class GridSpiAdapter

Parameters:

spiCtx - SPI context.

Throws:

GridSpiException - In case of errors.

onContextDestroyed0

protected void onContextDestroyed0()

Method to be called in the beginning of onContextDestroyed() method.

Overrides:

onContextDestroyed0 in class GridSpiAdapter

getBalancedNode

public GridNode getBalancedNode(GridComputeTaskSession ses,
                       List<GridNode> top,
                       GridComputeJob job)

Gets balanced node for specified job within given task session.

Specified by:

getBalancedNode in interface GridLoadBalancingSpi

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.

getConsistentAttributeNames

protected List<String> getConsistentAttributeNames()

Returns back a list of attributes that should be consistent for this SPI. Consistency means that remote node has to have the same attribute with the same value.

Overrides:

getConsistentAttributeNames in class GridSpiAdapter

Returns:

List or attribute names.

toString

public String toString()

Overrides:

toString in class Object