BaseLoadBalancer (Apache HBase

java.lang.Object
- org.apache.hadoop.hbase.master.balancer.BaseLoadBalancer

所有已实现的接口:

org.apache.hadoop.conf.Configurable, ConfigurationObserver, LoadBalancer, Stoppable

直接已知子类:

FavoredNodeLoadBalancer, SimpleLoadBalancer, StochasticLoadBalancer
```
@InterfaceAudience.Private
public abstract class BaseLoadBalancer
extends Object
implements LoadBalancer
```
The base class for load balancers. It provides the the functions used to by AssignmentManager to assign regions in the edge cases. It doesn't provide an implementation of the actual balancing algorithm.

嵌套类概要

嵌套类
限定符和类型	类和说明
`protected static class`	`BaseLoadBalancer.Cluster` An efficient array based implementation similar to ClusterState for keeping the status of the cluster in terms of region assignment and distribution.

字段概要

字段
限定符和类型	字段和说明
`protected ClusterMetrics`	`clusterStatus`
`protected org.apache.hadoop.conf.Configuration`	`config`
`protected boolean`	`maintenanceMode`
`protected ServerName`	`masterServerName`
`protected MetricsBalancer`	`metricsBalancer`
`protected static int`	`MIN_SERVER_BALANCE`
`protected boolean`	`onlySystemTablesOnMaster`
`protected float`	`overallSlop`
`protected RackManager`	`rackManager`
`protected org.apache.hadoop.hbase.master.balancer.RegionLocationFinder`	`regionFinder`
`protected MasterServices`	`services`
`protected float`	`slop`
`protected boolean`	`useRegionFinder`

从接口继承的字段 org.apache.hadoop.hbase.master.LoadBalancer
BOGUS_SERVER_NAME, SYSTEM_TABLES_ON_MASTER, TABLES_ON_MASTER

构造器概要

构造器
限定符	构造器和说明
`protected`	`BaseLoadBalancer()` The constructor that uses the basic MetricsBalancer
`protected`	`BaseLoadBalancer(MetricsBalancer metricsBalancer)` This Constructor accepts an instance of MetricsBalancer, which will be used instead of creating a new one

方法概要

所有方法实例方法具体方法
限定符和类型	方法和说明
`protected boolean`	`areSomeRegionReplicasColocated(BaseLoadBalancer.Cluster c)` Subclasses should implement this to return true if the cluster has nodes that hosts multiple replicas for the same region, or, if there are multiple racks and the same rack hosts replicas of the same region
`protected Map<ServerName,List<RegionInfo>>`	`assignMasterSystemRegions(Collection<RegionInfo> regions, List<ServerName> servers)` If master is configured to carry system tables only, in here is where we figure what to assign it.
`protected List<RegionPlan>`	`balanceMasterRegions(Map<ServerName,List<RegionInfo>> clusterMap)` Balance the regions that should be on master regionserver.
`protected BaseLoadBalancer.Cluster`	`createCluster(List<ServerName> servers, Collection<RegionInfo> regions, boolean hasRegionReplica)`
`org.apache.hadoop.conf.Configuration`	`getConf()`
`protected Map<ServerName,List<RegionInfo>>`	`getRegionAssignmentsByServer(Collection<RegionInfo> regions)`
`void`	`initialize()` Initialize the load balancer.
`boolean`	`isStopped()`
`protected boolean`	`needsBalance(BaseLoadBalancer.Cluster c)`
`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(RegionInfo regionInfo, List<ServerName> servers)` Used to assign a single region to a random server.
`void`	`regionOffline(RegionInfo regionInfo)` Marks the region as offline at balancer.
`void`	`regionOnline(RegionInfo regionInfo, ServerName sn)` Marks the region as online at balancer.
`Map<ServerName,List<RegionInfo>>`	`retainAssignment(Map<RegionInfo,ServerName> regions, List<ServerName> servers)` Generates a bulk assignment startup plan, attempting to reuse the existing assignment information from META, but adjusting for the specified list of available/online servers available for assignment.
`Map<ServerName,List<RegionInfo>>`	`roundRobinAssignment(List<RegionInfo> regions, List<ServerName> servers)` Generates a bulk assignment plan to be used on cluster startup using a simple round-robin assignment.
`void`	`setClusterLoad(Map<TableName,Map<ServerName,List<RegionInfo>>> clusterLoad)` Pass RegionStates and allow balancer to set the current cluster load.
`void`	`setClusterMetrics(ClusterMetrics st)` Set the current cluster status.
`void`	`setConf(org.apache.hadoop.conf.Configuration conf)`
`void`	`setMasterServices(MasterServices masterServices)` Set the master service.
`void`	`setRackManager(RackManager rackManager)`
`protected void`	`setSlop(org.apache.hadoop.conf.Configuration conf)`
`boolean`	`shouldBeOnMaster(RegionInfo region)` Check if a region belongs to some system table.
`void`	`stop(String why)`
`void`	`updateBalancerStatus(boolean status)` Updates the balancer status tag reported to JMX

从类继承的方法 java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

从接口继承的方法 org.apache.hadoop.hbase.master.LoadBalancer
balanceCluster, balanceCluster, isMasterCanHostUserRegions, isSystemTablesOnlyOnMaster, isTablesOnMaster

- 字段详细资料
  - MIN_SERVER_BALANCE
```
protected static final int MIN_SERVER_BALANCE
```
    另请参阅:
    
    常量字段值
  - regionFinder
```
protected org.apache.hadoop.hbase.master.balancer.RegionLocationFinder regionFinder
```
  - useRegionFinder
```
protected boolean useRegionFinder
```
  - slop
```
protected float slop
```
  - overallSlop
```
protected float overallSlop
```
  - config
```
protected org.apache.hadoop.conf.Configuration config
```
  - rackManager
```
protected RackManager rackManager
```
  - metricsBalancer
```
protected MetricsBalancer metricsBalancer
```
  - clusterStatus
```
protected ClusterMetrics clusterStatus
```
  - masterServerName
```
protected ServerName masterServerName
```
  - services
```
protected MasterServices services
```
  - onlySystemTablesOnMaster
```
protected boolean onlySystemTablesOnMaster
```
  - maintenanceMode
```
protected boolean maintenanceMode
```
- 构造器详细资料
  - BaseLoadBalancer
```
protected BaseLoadBalancer()
```
    The constructor that uses the basic MetricsBalancer
  - BaseLoadBalancer
```
protected BaseLoadBalancer(MetricsBalancer metricsBalancer)
```
    This Constructor accepts an instance of MetricsBalancer, which will be used instead of creating a new one
- 方法详细资料
  - setConf
```
public void setConf(org.apache.hadoop.conf.Configuration conf)
```
    指定者:
    
    setConf 在接口中 org.apache.hadoop.conf.Configurable
  - setSlop
```
protected void setSlop(org.apache.hadoop.conf.Configuration conf)
```
  - shouldBeOnMaster
```
public boolean shouldBeOnMaster(RegionInfo region)
```
    Check if a region belongs to some system table. If so, the primary replica may be expected to be put on the master regionserver.
  - balanceMasterRegions
```
protected List<RegionPlan> balanceMasterRegions(Map<ServerName,List<RegionInfo>> clusterMap)
```
    Balance the regions that should be on master regionserver.
  - assignMasterSystemRegions
```
protected Map<ServerName,List<RegionInfo>> assignMasterSystemRegions(Collection<RegionInfo> regions,
                                                                     List<ServerName> servers)
```
    If master is configured to carry system tables only, in here is where we figure what to assign it.
  - getConf
```
public org.apache.hadoop.conf.Configuration getConf()
```
    指定者:
    
    getConf 在接口中 org.apache.hadoop.conf.Configurable
  - setClusterMetrics
```
public void setClusterMetrics(ClusterMetrics st)
```
    从接口复制的说明: LoadBalancer
    
    Set the current cluster status. This allows a LoadBalancer to map host name to a server
    
    指定者:
    
    setClusterMetrics 在接口中 LoadBalancer
  - setClusterLoad
```
public void setClusterLoad(Map<TableName,Map<ServerName,List<RegionInfo>>> clusterLoad)
```
    从接口复制的说明: LoadBalancer
    
    Pass RegionStates and allow balancer to set the current cluster load.
    
    指定者:
    
    setClusterLoad 在接口中 LoadBalancer
  - setMasterServices
```
public void setMasterServices(MasterServices masterServices)
```
    从接口复制的说明: LoadBalancer
    
    Set the master service.
    
    指定者:
    
    setMasterServices 在接口中 LoadBalancer
  - postMasterStartupInitialize
```
public void postMasterStartupInitialize()
```
    从接口复制的说明: LoadBalancer
    
    If balancer needs to do initialization after Master has started up, lets do that here.
    
    指定者:
    
    postMasterStartupInitialize 在接口中 LoadBalancer
  - setRackManager
```
public void setRackManager(RackManager rackManager)
```
  - needsBalance
```
protected boolean needsBalance(BaseLoadBalancer.Cluster c)
```
  - areSomeRegionReplicasColocated
```
protected boolean areSomeRegionReplicasColocated(BaseLoadBalancer.Cluster c)
```
    Subclasses should implement this to return true if the cluster has nodes that hosts multiple replicas for the same region, or, if there are multiple racks and the same rack hosts replicas of the same region
    
    参数:
    
    c - Cluster information
    
    返回:
    
    whether region replicas are currently co-located
  - roundRobinAssignment
```
public Map<ServerName,List<RegionInfo>> roundRobinAssignment(List<RegionInfo> regions,
                                                             List<ServerName> servers)
                                                      throws HBaseIOException
```
    Generates a bulk assignment plan to be used on cluster startup using a simple round-robin assignment.
    Takes a list of all the regions and all the servers in the cluster and returns a map of each server to the regions that it should be assigned.
    Currently implemented as a round-robin assignment. Same invariant as load balancing, all servers holding floor(avg) or ceiling(avg). TODO: Use block locations from HDFS to place regions with their blocks
    
    指定者:
    
    roundRobinAssignment 在接口中 LoadBalancer
    
    参数:
    
    regions - all regions
    
    servers - all servers
    
    返回:
    
    map of server to the regions it should take, or null if no assignment is possible (ie. no regions or no servers)
    
    抛出:
    
    HBaseIOException
  - createCluster
```
protected BaseLoadBalancer.Cluster createCluster(List<ServerName> servers,
                                                 Collection<RegionInfo> regions,
                                                 boolean hasRegionReplica)
```
  - randomAssignment
```
public ServerName randomAssignment(RegionInfo regionInfo,
                                   List<ServerName> servers)
                            throws HBaseIOException
```
    Used to assign a single region to a random server.
    
    指定者:
    
    randomAssignment 在接口中 LoadBalancer
    
    参数:
    
    regionInfo - Region for which this selection is being done.
    
    返回:
    
    Servername
    
    抛出:
    
    HBaseIOException
  - retainAssignment
```
public Map<ServerName,List<RegionInfo>> retainAssignment(Map<RegionInfo,ServerName> regions,
                                                         List<ServerName> servers)
                                                  throws HBaseIOException
```
    Generates a bulk assignment startup plan, attempting to reuse the existing assignment information from META, but adjusting for the specified list of available/online servers available for assignment.
    Takes a map of all regions to their existing assignment from META. Also takes a list of online servers for regions to be assigned to. Attempts to retain all assignment, so in some instances initial assignment will not be completely balanced.
    Any leftover regions without an existing server to be assigned to will be assigned randomly to available servers.
    
    指定者:
    
    retainAssignment 在接口中 LoadBalancer
    
    参数:
    
    regions - regions and existing assignment from meta
    
    servers - available servers
    
    返回:
    
    map of servers and regions to be assigned to them
    
    抛出:
    
    HBaseIOException
  - initialize
```
public void initialize()
                throws HBaseIOException
```
    从接口复制的说明: LoadBalancer
    
    Initialize the load balancer. Must be called after setters.
    
    指定者:
    
    initialize 在接口中 LoadBalancer
    
    抛出:
    
    HBaseIOException
  - regionOnline
```
public void regionOnline(RegionInfo regionInfo,
                         ServerName sn)
```
    从接口复制的说明: LoadBalancer
    
    Marks the region as online at balancer.
    
    指定者:
    
    regionOnline 在接口中 LoadBalancer
  - regionOffline
```
public void regionOffline(RegionInfo regionInfo)
```
    从接口复制的说明: LoadBalancer
    
    Marks the region as offline at balancer.
    
    指定者:
    
    regionOffline 在接口中 LoadBalancer
  - isStopped
```
public boolean isStopped()
```
    指定者:
    
    isStopped 在接口中 Stoppable
  - stop
```
public void stop(String why)
```
    指定者:
    
    stop 在接口中 Stoppable
  - updateBalancerStatus
```
public void updateBalancerStatus(boolean status)
```
    Updates the balancer status tag reported to JMX
    
    指定者:
    
    updateBalancerStatus 在接口中 LoadBalancer
  - getRegionAssignmentsByServer
```
protected Map<ServerName,List<RegionInfo>> getRegionAssignmentsByServer(Collection<RegionInfo> regions)
```
  - onConfigurationChange
```
public void onConfigurationChange(org.apache.hadoop.conf.Configuration conf)
```
    从接口复制的说明: ConfigurationObserver
    
    This method would be called by the ConfigurationManager object when the Configuration object is reloaded from disk.
    
    指定者:
    
    onConfigurationChange 在接口中 ConfigurationObserver
    
    指定者:
    
    onConfigurationChange 在接口中 LoadBalancer

类 BaseLoadBalancer

嵌套类概要

字段概要

从接口继承的字段 org.apache.hadoop.hbase.master.LoadBalancer

构造器概要

方法概要

从类继承的方法 java.lang.Object

从接口继承的方法 org.apache.hadoop.hbase.master.LoadBalancer

字段详细资料

MIN_SERVER_BALANCE

regionFinder

useRegionFinder

slop

overallSlop

config

rackManager

metricsBalancer

clusterStatus

masterServerName

services

onlySystemTablesOnMaster

maintenanceMode

构造器详细资料

BaseLoadBalancer

BaseLoadBalancer

方法详细资料

setConf

setSlop

shouldBeOnMaster

balanceMasterRegions

assignMasterSystemRegions

getConf

setClusterMetrics

setClusterLoad

setMasterServices

postMasterStartupInitialize

setRackManager

needsBalance

areSomeRegionReplicasColocated

roundRobinAssignment

createCluster

randomAssignment

retainAssignment

initialize

regionOnline

regionOffline

isStopped

stop

updateBalancerStatus

getRegionAssignmentsByServer

onConfigurationChange