org.apache.hadoop.hbase.master
Class HMaster

java.lang.Object
  java.lang.Thread
      org.apache.hadoop.hbase.master.HMaster

All Implemented Interfaces:

java.lang.Runnable, Abortable, HBaseRPCProtocolVersion, HMasterInterface, HMasterRegionInterface, MasterServices, Server, Stoppable, org.apache.hadoop.ipc.VersionedProtocol

Direct Known Subclasses:

HMasterCommandLine.LocalHMaster

public class HMaster
extends java.lang.Thread
implements HMasterInterface, HMasterRegionInterface, MasterServices, Server

HMaster is the "master server" for HBase. An HBase cluster has one active master. If many masters are started, all compete. Whichever wins goes on to run the cluster. All others park themselves in their constructor until master or cluster shutdown or until the active master loses its lease in zookeeper. Thereafter, all running master jostle to take over master role.

The Master can be asked shutdown the cluster. See shutdown(). In this case it will tell all regionservers to go down and then wait on them all reporting in that they are down. This master will then shut itself down.

You can also shutdown just this master. Call stopMaster().

See Also:

HMasterInterface, HMasterRegionInterface, Watcher

Nested Class Summary

Nested classes/interfaces inherited from class java.lang.Thread

java.lang.Thread.State, java.lang.Thread.UncaughtExceptionHandler

Field Summary

static java.lang.String

MASTER

Fields inherited from class java.lang.Thread

MAX_PRIORITY, MIN_PRIORITY, NORM_PRIORITY

Fields inherited from interface org.apache.hadoop.hbase.ipc.HBaseRPCProtocolVersion

versionID

Constructor Summary

HMaster(org.apache.hadoop.conf.Configuration conf)
Initializes the HMaster.

Method Summary

void	abort(java.lang.String msg, java.lang.Throwable t) Abort the server or client.
void	addColumn(byte[] tableName, HColumnDescriptor column) Adds a column to the specified table
protected HMsg[]	adornRegionServerAnswer(HServerInfo hsi, HMsg[] msgs) Override if you'd add messages to return to regionserver hsi or to send an exception.
void	assign(byte[] regionName, boolean force) Assign a region to a server chosen at random.
void	assignRegion(HRegionInfo hri)
boolean	balance() Run the balancer.
boolean	balanceSwitch(boolean b) Turn the load balancer on or off.
void	checkTableModifiable(byte[] tableName) Check table is modifiable; i.e.
void	clearFromTransition(HRegionInfo hri)
static HMaster	constructMaster(java.lang.Class<? extends HMaster> masterClass, org.apache.hadoop.conf.Configuration conf) Utility for constructing an instance of the passed HMaster class.
protected org.apache.hadoop.io.MapWritable	createConfigurationSubset()
void	createTable(HTableDescriptor desc, byte[][] splitKeys) Creates a new table.
void	createTable(HTableDescriptor desc, byte[][] splitKeys, boolean sync)
void	deleteColumn(byte[] tableName, byte[] c) Deletes a column from the specified table.
void	deleteTable(byte[] tableName) Deletes a table
void	disableTable(byte[] tableName) Take table offline
void	enableTable(byte[] tableName) Puts the table on-line (only needed if table has been previously taken offline)
AssignmentManager	getAssignmentManager()
CatalogTracker	getCatalogTracker()
ClusterStatus	getClusterStatus() Return cluster status.
org.apache.hadoop.conf.Configuration	getConfiguration() Gets the configuration object for this server.
ExecutorService	getExecutorService()
InfoServer	getInfoServer()
HServerAddress	getMasterAddress()
MasterFileSystem	getMasterFileSystem()
long	getProtocolVersion(java.lang.String protocol, long clientVersion)
ServerManager	getServerManager()
java.lang.String	getServerName() Gets the unique server name for this server.
ZooKeeperWatcher	getZooKeeper() Gets the ZooKeeper instance for this server.
ZooKeeperWatcher	getZooKeeperWatcher() Get the ZK wrapper object - needed by master_jsp.java
boolean	isActiveMaster() Report whether this master is currently the active master or not.
boolean	isInitialized() Report whether this master has completed with its initialization and is ready.
boolean	isMasterRunning()
boolean	isStopped()
static void	main(java.lang.String[] args)
void	modifyColumn(byte[] tableName, HColumnDescriptor descriptor) Modifies an existing column on the specified table
void	modifyTable(byte[] tableName, HTableDescriptor htd) Modify a table's metadata
void	move(byte[] encodedRegionName, byte[] destServerName) Move the region r to dest.
HMsg[]	regionServerReport(HServerInfo serverInfo, HMsg[] msgs, HRegionInfo[] mostLoadedRegions) Called to renew lease, tell master what the region server is doing and to receive new instructions from the master
org.apache.hadoop.io.MapWritable	regionServerStartup(HServerInfo serverInfo, long serverCurrentTime) Called when a region server first starts
void	run() Main processing loop for the HMaster.
void	setCatalogJanitorEnabled(boolean b) Switch for the background CatalogJanitor thread.
void	shutdown() Shutdown an HBase cluster.
void	stop(java.lang.String why) Stop this service.
void	stopMaster() Stop HBase Master only.
void	unassign(byte[] regionName, boolean force) Unassign a region from current hosting regionserver.

Methods inherited from class java.lang.Thread

activeCount, checkAccess, clone, countStackFrames, currentThread, destroy, dumpStack, enumerate, getAllStackTraces, getContextClassLoader, getDefaultUncaughtExceptionHandler, getId, getName, getPriority, getStackTrace, getState, getThreadGroup, getUncaughtExceptionHandler, holdsLock, interrupt, interrupted, isAlive, isDaemon, isInterrupted, join, join, join, resume, setContextClassLoader, setDaemon, setDefaultUncaughtExceptionHandler, setName, setPriority, setUncaughtExceptionHandler, sleep, sleep, start, stop, stop, suspend, toString, yield

Methods inherited from class java.lang.Object

equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

MASTER

public static final java.lang.String MASTER

See Also:

Constant Field Values

Constructor Detail

HMaster

public HMaster(org.apache.hadoop.conf.Configuration conf)
        throws java.io.IOException,
               org.apache.zookeeper.KeeperException,
               java.lang.InterruptedException

Initializes the HMaster. The steps are as follows:

1. Initialize HMaster RPC and address
2. Connect to ZooKeeper.

Remaining steps of initialization occur in run() so that they run in their own thread rather than within the context of the constructor.

Throws:

java.lang.InterruptedException

java.io.IOException

org.apache.zookeeper.KeeperException

Method Detail

run

public void run()

Main processing loop for the HMaster.

1. Block until becoming active master
2. Finish initialization via finishInitialization()
3. Enter loop until we are stopped
4. Stop services and perform cleanup once stopped

Specified by:

run in interface java.lang.Runnable

Overrides:

run in class java.lang.Thread

getMasterAddress

public HServerAddress getMasterAddress()

Returns:

HServerAddress of the master server

getProtocolVersion

public long getProtocolVersion(java.lang.String protocol,
                               long clientVersion)

Specified by:

getProtocolVersion in interface org.apache.hadoop.ipc.VersionedProtocol

getInfoServer

public InfoServer getInfoServer()

Returns:

InfoServer object. Maybe null.

getConfiguration

public org.apache.hadoop.conf.Configuration getConfiguration()

Description copied from interface: Server

Gets the configuration object for this server.

Specified by:

getConfiguration in interface Server

getServerManager

public ServerManager getServerManager()

Specified by:

getServerManager in interface MasterServices

Returns:

Master's ServerManager instance.

getExecutorService

public ExecutorService getExecutorService()

Specified by:

getExecutorService in interface MasterServices

Returns:

Master's instance of ExecutorService

getMasterFileSystem

public MasterFileSystem getMasterFileSystem()

Specified by:

getMasterFileSystem in interface MasterServices

Returns:

Master's filesystem MasterFileSystem utility class.

getZooKeeperWatcher

public ZooKeeperWatcher getZooKeeperWatcher()

Get the ZK wrapper object - needed by master_jsp.java

Returns:

the zookeeper wrapper

regionServerStartup

public org.apache.hadoop.io.MapWritable regionServerStartup(HServerInfo serverInfo,
                                                            long serverCurrentTime)
                                                     throws java.io.IOException

Description copied from interface: HMasterRegionInterface

Called when a region server first starts

Specified by:

regionServerStartup in interface HMasterRegionInterface

Parameters:

serverInfo - server info

serverCurrentTime - The current time of the region server in ms

Returns:

Configuration for the regionserver to use: e.g. filesystem, hbase rootdir, etc.

Throws:

java.io.IOException - e

createConfigurationSubset

protected org.apache.hadoop.io.MapWritable createConfigurationSubset()

Returns:

Subset of configuration to pass initializing regionservers: e.g. the filesystem to use and root directory to use.

regionServerReport

public HMsg[] regionServerReport(HServerInfo serverInfo,
                                 HMsg[] msgs,
                                 HRegionInfo[] mostLoadedRegions)
                          throws java.io.IOException

Description copied from interface: HMasterRegionInterface

Called to renew lease, tell master what the region server is doing and to receive new instructions from the master

Specified by:

regionServerReport in interface HMasterRegionInterface

Parameters:

serverInfo - server's address and start code

msgs - things the region server wants to tell the master

mostLoadedRegions - Array of HRegionInfos that should contain the reporting server's most loaded regions. These are candidates for being rebalanced.

Returns:

instructions from the master to the region server

Throws:

java.io.IOException - e

adornRegionServerAnswer

protected HMsg[] adornRegionServerAnswer(HServerInfo hsi,
                                         HMsg[] msgs)
                                  throws java.io.IOException

Override if you'd add messages to return to regionserver hsi or to send an exception.

Parameters:

msgs - Messages to add to

Returns:

Messages to return to

Throws:

java.io.IOException - exceptions that were injected for the region servers

isMasterRunning

public boolean isMasterRunning()

Specified by:

isMasterRunning in interface HMasterInterface

Returns:

true if master is available

balance

public boolean balance()

Description copied from interface: HMasterInterface

Run the balancer. Will run the balancer and if regions to move, it will go ahead and do the reassignments. Can NOT run for various reasons. Check logs.

Specified by:

balance in interface HMasterInterface

Returns:

True if balancer ran, false otherwise.

balanceSwitch

public boolean balanceSwitch(boolean b)

Description copied from interface: HMasterInterface

Turn the load balancer on or off.

Specified by:

balanceSwitch in interface HMasterInterface

Parameters:

b - If true, enable balancer. If false, disable balancer.

Returns:

Previous balancer value

setCatalogJanitorEnabled

public void setCatalogJanitorEnabled(boolean b)

Switch for the background CatalogJanitor thread. Used for testing. The thread will continue to run. It will just be a noop if disabled.

Parameters:

b - If false, the catalog janitor won't do anything.

move

public void move(byte[] encodedRegionName,
                 byte[] destServerName)
          throws UnknownRegionException

Description copied from interface: HMasterInterface

Move the region r to dest.

Specified by:

move in interface HMasterInterface

Parameters:

encodedRegionName - The encoded region name; i.e. the hash that makes up the region name suffix: e.g. if regionname is TestTable,0094429456,1289497600452.527db22f95c8a9e0116f0cc13c680396., then the encoded region name is: 527db22f95c8a9e0116f0cc13c680396.

destServerName - The servername of the destination regionserver. If passed the empty byte array we'll assign to a random server. A server name is made of host, port and startcode. Here is an example: host187.example.com,60020,1289493121758.

Throws:

UnknownRegionException - Thrown if we can't find a region named encodedRegionName

createTable

public void createTable(HTableDescriptor desc,
                        byte[][] splitKeys)
                 throws java.io.IOException

Description copied from interface: HMasterInterface

Creates a new table. If splitKeys are specified, then the table will be created with an initial set of multiple regions. If splitKeys is null, the table will be created with a single region.

Specified by:

createTable in interface HMasterInterface

Parameters:

desc - table descriptor

Throws:

java.io.IOException

createTable

public void createTable(HTableDescriptor desc,
                        byte[][] splitKeys,
                        boolean sync)
                 throws java.io.IOException

Throws:

java.io.IOException

deleteTable

public void deleteTable(byte[] tableName)
                 throws java.io.IOException

Description copied from interface: HMasterInterface

Deletes a table

Specified by:

deleteTable in interface HMasterInterface

Parameters:

tableName - table to delete

Throws:

java.io.IOException - e

addColumn

public void addColumn(byte[] tableName,
                      HColumnDescriptor column)
               throws java.io.IOException

Description copied from interface: HMasterInterface

Adds a column to the specified table

Specified by:

addColumn in interface HMasterInterface

Parameters:

tableName - table to modify

column - column descriptor

Throws:

java.io.IOException - e

modifyColumn

public void modifyColumn(byte[] tableName,
                         HColumnDescriptor descriptor)
                  throws java.io.IOException

Description copied from interface: HMasterInterface

Modifies an existing column on the specified table

Specified by:

modifyColumn in interface HMasterInterface

Parameters:

tableName - table name

descriptor - new column descriptor

Throws:

java.io.IOException - e

deleteColumn

public void deleteColumn(byte[] tableName,
                         byte[] c)
                  throws java.io.IOException

Description copied from interface: HMasterInterface

Deletes a column from the specified table. Table must be disabled.

Specified by:

deleteColumn in interface HMasterInterface

Parameters:

tableName - table to alter

c - column family to remove

Throws:

java.io.IOException - e

enableTable

public void enableTable(byte[] tableName)
                 throws java.io.IOException

Description copied from interface: HMasterInterface

Puts the table on-line (only needed if table has been previously taken offline)

Specified by:

enableTable in interface HMasterInterface

Parameters:

tableName - table to enable

Throws:

java.io.IOException - e

disableTable

public void disableTable(byte[] tableName)
                  throws java.io.IOException

Description copied from interface: HMasterInterface

Take table offline

Specified by:

disableTable in interface HMasterInterface

Parameters:

tableName - table to take offline

Throws:

java.io.IOException - e

modifyTable

public void modifyTable(byte[] tableName,
                        HTableDescriptor htd)
                 throws java.io.IOException

Description copied from interface: HMasterInterface

Modify a table's metadata

Specified by:

modifyTable in interface HMasterInterface

Parameters:

tableName - table to modify

htd - new descriptor for table

Throws:

java.io.IOException - e

checkTableModifiable

public void checkTableModifiable(byte[] tableName)
                          throws java.io.IOException

Description copied from interface: MasterServices

Check table is modifiable; i.e. exists and is offline.

Specified by:

checkTableModifiable in interface MasterServices

Parameters:

tableName - Name of table to check.

Throws:

TableNotDisabledException

TableNotFoundException

java.io.IOException

clearFromTransition

public void clearFromTransition(HRegionInfo hri)

getClusterStatus

public ClusterStatus getClusterStatus()

Description copied from interface: HMasterInterface

Return cluster status.

Specified by:

getClusterStatus in interface HMasterInterface

Returns:

cluster status

abort

public void abort(java.lang.String msg,
                  java.lang.Throwable t)

Description copied from interface: Abortable

Abort the server or client.

Specified by:

abort in interface Abortable

Parameters:

msg - Why we're aborting.

t - Throwable that caused abort. Can be null.

getZooKeeper

public ZooKeeperWatcher getZooKeeper()

Description copied from interface: Server

Gets the ZooKeeper instance for this server.

Specified by:

getZooKeeper in interface Server

getServerName

public java.lang.String getServerName()

Description copied from interface: Server

Gets the unique server name for this server. If a RegionServer, it returns a concatenation of hostname, port and startcode formatted as <hostname> ',' <port> ',' <startcode>. If the master, it returns <hostname> ':' <port>'.

Specified by:

getServerName in interface Server

Returns:

unique server name

getCatalogTracker

public CatalogTracker getCatalogTracker()

Specified by:

getCatalogTracker in interface Server

Returns:

Master's instance of CatalogTracker

getAssignmentManager

public AssignmentManager getAssignmentManager()

Specified by:

getAssignmentManager in interface MasterServices

Returns:

Master's instance of the AssignmentManager

shutdown

public void shutdown()

Description copied from interface: HMasterInterface

Shutdown an HBase cluster.

Specified by:

shutdown in interface HMasterInterface

stopMaster

public void stopMaster()

Description copied from interface: HMasterInterface

Stop HBase Master only. Does not shutdown the cluster.

Specified by:

stopMaster in interface HMasterInterface

stop

public void stop(java.lang.String why)

Description copied from interface: Stoppable

Stop this service.

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.

isActiveMaster

public boolean isActiveMaster()

Report whether this master is currently the active master or not. If not active master, we are parked on ZK waiting to become active. This method is used for testing.

Returns:

true if active master, false if not.

isInitialized

public boolean isInitialized()

Report whether this master has completed with its initialization and is ready. If ready, the master is also the active master. A standby master is never ready. This method is used for testing.

Returns:

true if master is ready to go, false if not.

assign

public void assign(byte[] regionName,
                   boolean force)
            throws java.io.IOException

Description copied from interface: HMasterInterface

Assign a region to a server chosen at random.

Specified by:

assign in interface HMasterInterface

Parameters:

regionName - Region to assign. Will use existing RegionPlan if one found.

force - If true, will force the assignment.

Throws:

java.io.IOException

assignRegion

public void assignRegion(HRegionInfo hri)

unassign

public void unassign(byte[] regionName,
                     boolean force)
              throws java.io.IOException

Description copied from interface: HMasterInterface

Unassign a region from current hosting regionserver. Region will then be assigned to a regionserver chosen at random. Region could be reassigned back to the same server. Use HMasterInterface.move(byte[], byte[]) if you want to control the region movement.

Specified by:

unassign in interface HMasterInterface

Parameters:

regionName - Region to unassign. Will clear any existing RegionPlan if one found.

force - If true, force unassign (Will remove region from regions-in-transition too if present).

Throws:

java.io.IOException

constructMaster

public static HMaster constructMaster(java.lang.Class<? extends HMaster> masterClass,
                                      org.apache.hadoop.conf.Configuration conf)

Utility for constructing an instance of the passed HMaster class.

Parameters:

masterClass -

conf -

Returns:

HMaster instance.

main

public static void main(java.lang.String[] args)
                 throws java.lang.Exception

Throws:

java.lang.Exception

See Also:

HMasterCommandLine