org.gridgain.grid.spi.failover.jobstealing
Class GridJobStealingFailoverSpi

java.lang.Object
  org.gridgain.grid.spi.GridSpiAdapter
      org.gridgain.grid.spi.failover.jobstealing.GridJobStealingFailoverSpi

All Implemented Interfaces:

GridFailoverSpi, GridJobStealingFailoverSpiMBean, GridSpi, GridSpiJsonConfigurable, GridSpiManagementMBean

@GridSpiInfo(author="GridGain Systems",
             url="www.gridgain.com",
             email="support@gridgain.com",
             version="3.6.0e.13012012")
@GridSpiMultipleInstancesSupport(value=true)
public class GridJobStealingFailoverSpi
extends GridSpiAdapter
implements GridFailoverSpi, GridJobStealingFailoverSpiMBean

Job stealing failover SPI needs to always be used in conjunction with GridJobStealingCollisionSpi SPI. When GridJobStealingCollisionSpi receives a steal request and rejects jobs so they can be routed to the appropriate node, it is the responsibility of this GridJobStealingFailoverSpi SPI to make sure that the job is indeed re-routed to the node that has sent the initial request to steal it.

GridJobStealingFailoverSpi knows where to route a job based on the GridJobStealingCollisionSpi.THIEF_NODE_ATTR job context attribute (see GridJobContext). Prior to rejecting a job, GridJobStealingCollisionSpi will populate this attribute with the ID of the node that wants to steal this job. Then GridJobStealingFailoverSpi will read the value of this attribute and route the job to the node specified.

If failure is caused by a node crash, and not by steal request, then this SPI behaves identically to GridAlwaysFailoverSpi, and tries to find the next balanced node to fail-over a job to.

Configuration

Mandatory

This SPI has no mandatory configuration parameters.

Optional

This SPI has following optional configuration parameters:

• Maximum failover attempts for a single job (see GridJobStealingFailoverSpi.setMaximumFailoverAttempts(int)).

Here is a Java example on how to configure grid with GridJobStealingFailoverSpi.

 GridJobStealingFailoverSpi spi = new GridJobStealingFailoverSpi();

 // Override maximum failover attempts.
 spi.setMaximumFailoverAttempts(5);

 GridConfigurationAdapter cfg = new GridConfigurationAdapter();

 // Override default failover SPI.
 cfg.setFailoverSpiSpi(spi);

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

Here is an example of how to configure GridJobStealingFailoverSpi from Spring XML configuration file.

 <property name="failoverSpi">
     <bean class="org.gridgain.grid.spi.failover.jobstealing.GridJobStealingFailoverSpi">
         <property name="maximumFailoverAttempts" value="5"/>
     </bean>
 </property>
 

For information about Spring framework visit www.springframework.org

Wiki & Forum:

Wiki
Forum

See Also:

GridFailoverSpi

Field Summary

static int

DFLT_MAX_FAILOVER_ATTEMPTS Maximum number of attempts to execute a failed job on another node (default is 5).

Constructor Summary

GridJobStealingFailoverSpi()

Method Summary

GridNode	failover(GridFailoverContext ctx, List<GridNode> top) This method is called when method GridTask.result(GridJobResult, List) returns value GridJobResultPolicy.FAILOVER policy indicating that the result of job execution must be failed over.
protected List<String>	getConsistentAttributeNames() Returns back a list of attributes that should be consistent for this SPI.
int	getMaximumFailoverAttempts() Gets maximum number of attempts to execute a failed job on another node.
Map<String,Object>	getNodeAttributes() This method is called before SPI starts (before method GridSpi.spiStart(String) is called).
int	getTotalFailedOverJobsCount() Get total number of jobs that were failed over including stolen ones.
void	setMaximumFailoverAttempts(int maxFailoverAttempts) Sets maximum number of attempts to execute a failed job on another node.
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, checkConfigurationConsistency, configInfo, createSpiAttributeName, getAuthor, getGridGainHome, getLocalNodeId, getName, getSpiContext, getStartTimestamp, getStartTimestampFormatted, getUpTime, getUpTimeFormatted, getVendorEmail, getVendorUrl, getVersion, injectables, onContextDestroyed, onContextInitialized, registerMBean, setJson, 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.GridSpiJsonConfigurable

setJson

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

getAuthor, getGridGainHome, getLocalNodeId, getName, getStartTimestamp, getStartTimestampFormatted, getUpTime, getUpTimeFormatted, getVendorEmail, getVendorUrl, getVersion

Field Detail

DFLT_MAX_FAILOVER_ATTEMPTS

public static final int DFLT_MAX_FAILOVER_ATTEMPTS

Maximum number of attempts to execute a failed job on another node (default is 5).

See Also:

Constant Field Values

Constructor Detail

GridJobStealingFailoverSpi

public GridJobStealingFailoverSpi()

Method Detail

getMaximumFailoverAttempts

public int getMaximumFailoverAttempts()

Gets maximum number of attempts to execute a failed job on another node. If job gets stolen and thief node exists then it is not considered as failed job. If not specified, GridJobStealingFailoverSpi.DFLT_MAX_FAILOVER_ATTEMPTS value will be used.

Specified by:

getMaximumFailoverAttempts in interface GridJobStealingFailoverSpiMBean

Returns:

Maximum number of attempts to execute a failed job on another node.

setMaximumFailoverAttempts

@GridSpiConfiguration(optional=true)
public void setMaximumFailoverAttempts(int maxFailoverAttempts)

Sets maximum number of attempts to execute a failed job on another node. If job gets stolen and thief node exists then it is not considered as failed job. If not specified, GridJobStealingFailoverSpi.DFLT_MAX_FAILOVER_ATTEMPTS value will be used.

Note this value must be identical for all grid nodes in the grid.

Parameters:

maxFailoverAttempts - Maximum number of attempts to execute a failed job on another node.

getTotalFailedOverJobsCount

public int getTotalFailedOverJobsCount()

Get total number of jobs that were failed over including stolen ones.

Specified by:

getTotalFailedOverJobsCount in interface GridJobStealingFailoverSpiMBean

Returns:

Total number of failed over jobs.

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. Kernel 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

Throws:

GridSpiException - Throws in case of any error.

Returns:

Map of local node attributes this SPI wants to add.

spiStart

public void spiStart(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.

failover

public GridNode failover(GridFailoverContext ctx,
                         List<GridNode> top)

This method is called when method GridTask.result(GridJobResult, List) returns value GridJobResultPolicy.FAILOVER policy indicating that the result of job execution must be failed over. Implementation of this method should examine failover context and choose one of the grid nodes from supplied topology to retry job execution on it. For best performance it is advised that GridFailoverContext.getBalancedNode(List) method is used to select node for execution of failed job.

Specified by:

failover in interface GridFailoverSpi

Parameters:

ctx - Failover context.

top - Collection of all grid nodes within task topology (may include failed node).

Returns:

New node to route this job to or null if new node cannot be picked. If job failover fails (returns null) the whole task will be failed.

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