RSGroupBasedLoadBalancer (Apache HBase 1.4.11 API)

java.lang.Object
- org.apache.hadoop.hbase.rsgroup.RSGroupBasedLoadBalancer

All Implemented Interfaces:

org.apache.hadoop.conf.Configurable, ConfigurationObserver, LoadBalancer, RSGroupableBalancer, Stoppable
```
@InterfaceAudience.Private
public class RSGroupBasedLoadBalancer
extends Object
implements RSGroupableBalancer, LoadBalancer
```
GroupBasedLoadBalancer, used when Region Server Grouping is configured (HBase-6721) It does region balance based on a table's group membership. Most assignment methods contain two exclusive code paths: Online - when the group table is online and Offline - when it is unavailable. During Offline, assignments are assigned based on cached information in zookeeper. If unavailable (ie bootstrap) then regions are assigned randomly. Once the GROUP table has been assigned, the balancer switches to Online and will then start providing appropriate assignments for user tables.

Field Summary

Fields
Modifier and Type Field and Description

static String HBASE_GROUP_LOADBALANCER_CLASS
Config for pluggable load balancers
- Fields inherited from interface org.apache.hadoop.hbase.rsgroup.RSGroupableBalancer
  HBASE_RSGROUP_LOADBALANCER_CLASS
- Fields inherited from interface org.apache.hadoop.hbase.master.LoadBalancer
  BOGUS_SERVER_NAME

Fields
Modifier and Type	Field and Description
`static String`	`HBASE_GROUP_LOADBALANCER_CLASS` Config for pluggable load balancers

Constructor Summary

Constructors
Constructor and Description

RSGroupBasedLoadBalancer()

RSGroupBasedLoadBalancer(RSGroupInfoManager RSGroupInfoManager)

Constructors
Constructor and Description
`RSGroupBasedLoadBalancer()`
`RSGroupBasedLoadBalancer(RSGroupInfoManager RSGroupInfoManager)`

Method Summary

Methods
Modifier and Type	Method and Description
`List<RegionPlan>`	`balanceCluster(Map<ServerName,List<HRegionInfo>> clusterState)` Perform the major balance operation
`List<RegionPlan>`	`balanceCluster(TableName tableName, Map<ServerName,List<HRegionInfo>> clusterState)` Perform the major balance operation
`org.apache.hadoop.conf.Configuration`	`getConf()`
`Set<HRegionInfo>`	`getMisplacedRegions(Map<HRegionInfo,ServerName> regions)`
`Map<HRegionInfo,ServerName>`	`immediateAssignment(List<HRegionInfo> regions, List<ServerName> servers)` Sync assign a region
`void`	`initialize()` Initialize the load balancer.
`boolean`	`isOnline()`
`boolean`	`isStopped()`
`void`	`onConfigurationChange(org.apache.hadoop.conf.Configuration conf)` This method would be called by the `ConfigurationManager` object when the `Configuration` object is reloaded from disk.
`void`	`postMasterStartupInitialize()` If balancer needs to do initialization after Master has started up, lets do that here.
`ServerName`	`randomAssignment(HRegionInfo region, List<ServerName> servers)` Get a random region server from the list
`void`	`regionOffline(HRegionInfo regionInfo)` Marks the region as offline at balancer.
`void`	`regionOnline(HRegionInfo regionInfo, ServerName sn)` Marks the region as online at balancer.
`Map<ServerName,List<HRegionInfo>>`	`retainAssignment(Map<HRegionInfo,ServerName> regions, List<ServerName> servers)` Assign regions to the previously hosting region server
`Map<ServerName,List<HRegionInfo>>`	`roundRobinAssignment(List<HRegionInfo> regions, List<ServerName> servers)` Perform a Round Robin assignment of regions.
`void`	`setClusterStatus(ClusterStatus st)` Set the current cluster status.
`void`	`setConf(org.apache.hadoop.conf.Configuration conf)`
`void`	`setMasterServices(MasterServices masterServices)` Set the master service.
`void`	`stop(String why)` Stop this service.
`void`	`updateBalancerStatus(boolean status)`

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - HBASE_GROUP_LOADBALANCER_CLASS
```
public static final String HBASE_GROUP_LOADBALANCER_CLASS
```
    Config for pluggable load balancers
    
    See Also:
    Constant Field Values
- Constructor Detail
  - RSGroupBasedLoadBalancer
```
@InterfaceAudience.Private
public RSGroupBasedLoadBalancer()
```
  - RSGroupBasedLoadBalancer
```
@InterfaceAudience.Private
public RSGroupBasedLoadBalancer(RSGroupInfoManager RSGroupInfoManager)
```
- Method Detail
  - getConf
```
public org.apache.hadoop.conf.Configuration getConf()
```
    Specified by:
    
    getConf in interface org.apache.hadoop.conf.Configurable
  - setConf
```
public void setConf(org.apache.hadoop.conf.Configuration conf)
```
    Specified by:
    
    setConf in interface org.apache.hadoop.conf.Configurable
  - setClusterStatus
```
public void setClusterStatus(ClusterStatus st)
```
    Description copied from interface: LoadBalancer
    
    Set the current cluster status. This allows a LoadBalancer to map host name to a server
    
    Specified by:
    
    setClusterStatus in interface LoadBalancer
  - setMasterServices
```
public void setMasterServices(MasterServices masterServices)
```
    Description copied from interface: LoadBalancer
    
    Set the master service.
    
    Specified by:
    
    setMasterServices in interface LoadBalancer
  - balanceCluster
```
public List<RegionPlan> balanceCluster(TableName tableName,
                              Map<ServerName,List<HRegionInfo>> clusterState)
                                throws HBaseIOException
```
    Description copied from interface: LoadBalancer
    
    Perform the major balance operation
    
    Specified by:
    
    balanceCluster in interface LoadBalancer
    
    Returns:
    List of plans
    
    Throws:
    
    HBaseIOException
  - balanceCluster
```
public List<RegionPlan> balanceCluster(Map<ServerName,List<HRegionInfo>> clusterState)
                                throws HBaseIOException
```
    Description copied from interface: LoadBalancer
    
    Perform the major balance operation
    
    Specified by:
    
    balanceCluster in interface LoadBalancer
    
    Returns:
    List of plans
    
    Throws:
    
    HBaseIOException
  - roundRobinAssignment
```
public Map<ServerName,List<HRegionInfo>> roundRobinAssignment(List<HRegionInfo> regions,
                                                     List<ServerName> servers)
                                                       throws HBaseIOException
```
    Description copied from interface: LoadBalancer
    
    Perform a Round Robin assignment of regions.
    
    Specified by:
    
    roundRobinAssignment in interface LoadBalancer
    
    Returns:
    Map of servername to regioninfos
    
    Throws:
    
    HBaseIOException
  - retainAssignment
```
public Map<ServerName,List<HRegionInfo>> retainAssignment(Map<HRegionInfo,ServerName> regions,
                                                 List<ServerName> servers)
                                                   throws HBaseIOException
```
    Description copied from interface: LoadBalancer
    
    Assign regions to the previously hosting region server
    
    Specified by:
    
    retainAssignment in interface LoadBalancer
    
    Returns:
    List of plans
    
    Throws:
    
    HBaseIOException
  - immediateAssignment
```
public Map<HRegionInfo,ServerName> immediateAssignment(List<HRegionInfo> regions,
                                              List<ServerName> servers)
                                                throws HBaseIOException
```
    Description copied from interface: LoadBalancer
    
    Sync assign a region
    
    Specified by:
    
    immediateAssignment in interface LoadBalancer
    
    Returns:
    Map regioninfos to servernames
    
    Throws:
    
    HBaseIOException
  - randomAssignment
```
public ServerName randomAssignment(HRegionInfo region,
                          List<ServerName> servers)
                            throws HBaseIOException
```
    Description copied from interface: LoadBalancer
    
    Get a random region server from the list
    
    Specified by:
    
    randomAssignment in interface LoadBalancer
    
    Parameters:
    region - Region for which this selection is being done.
    
    Returns:
    Servername
    
    Throws:
    
    HBaseIOException
  - getMisplacedRegions
```
public Set<HRegionInfo> getMisplacedRegions(Map<HRegionInfo,ServerName> regions)
                                     throws IOException
```
    Throws:
    
    IOException
  - initialize
```
public void initialize()
                throws HBaseIOException
```
    Description copied from interface: LoadBalancer
    
    Initialize the load balancer. Must be called after setters.
    
    Specified by:
    
    initialize in interface LoadBalancer
    
    Throws:
    
    HBaseIOException
  - isOnline
```
public boolean isOnline()
```
  - regionOnline
```
public void regionOnline(HRegionInfo regionInfo,
                ServerName sn)
```
    Description copied from interface: LoadBalancer
    
    Marks the region as online at balancer.
    
    Specified by:
    
    regionOnline in interface LoadBalancer
  - regionOffline
```
public void regionOffline(HRegionInfo regionInfo)
```
    Description copied from interface: LoadBalancer
    
    Marks the region as offline at balancer.
    
    Specified by:
    
    regionOffline in interface LoadBalancer
  - onConfigurationChange
```
public void onConfigurationChange(org.apache.hadoop.conf.Configuration conf)
```
    Description copied from interface: ConfigurationObserver
    
    This method would be called by the ConfigurationManager object when the Configuration object is reloaded from disk.
    
    Specified by:
    
    onConfigurationChange in interface ConfigurationObserver
    
    Specified by:
    
    onConfigurationChange in interface LoadBalancer
  - stop
```
public void stop(String why)
```
    Description copied from interface: Stoppable
    
    Stop this service. Implementers should favor logging errors over throwing RuntimeExceptions.
    
    Specified by:
    
    stop in interface Stoppable
    
    Parameters:
    why - Why we're stopping.
  - isStopped
```
public boolean isStopped()
```
    Specified by:
    
    isStopped in interface Stoppable
    
    Returns:
    True if Stoppable.stop(String) has been closed.
  - postMasterStartupInitialize
```
public void postMasterStartupInitialize()
```
    Description copied from interface: LoadBalancer
    
    If balancer needs to do initialization after Master has started up, lets do that here.
    
    Specified by:
    
    postMasterStartupInitialize in interface LoadBalancer
  - updateBalancerStatus
```
public void updateBalancerStatus(boolean status)
```
    Specified by:
    
    updateBalancerStatus in interface LoadBalancer

Class RSGroupBasedLoadBalancer

Field Summary

Fields inherited from interface org.apache.hadoop.hbase.rsgroup.RSGroupableBalancer

Fields inherited from interface org.apache.hadoop.hbase.master.LoadBalancer

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

HBASE_GROUP_LOADBALANCER_CLASS

Constructor Detail

RSGroupBasedLoadBalancer

RSGroupBasedLoadBalancer

Method Detail

getConf

setConf

setClusterStatus

setMasterServices

balanceCluster

balanceCluster

roundRobinAssignment

retainAssignment

immediateAssignment

randomAssignment

getMisplacedRegions

initialize

isOnline

regionOnline

regionOffline

onConfigurationChange

stop

isStopped

postMasterStartupInitialize

updateBalancerStatus