Package org.apache.accumulo.server.master.balancer

Class DefaultLoadBalancer

java.lang.Object

org.apache.accumulo.server.master.balancer.TabletBalancer

org.apache.accumulo.server.master.balancer.DefaultLoadBalancer

public class DefaultLoadBalancer
extends TabletBalancer

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.accumulo.server.master.balancer.TabletBalancer

TabletBalancer.BalancerProblem, TabletBalancer.NoTservers, TabletBalancer.OutstandingMigrations

Field Summary

Fields

Modifier and Type	Field	Description
protected TabletBalancer.OutstandingMigrations	outstandingMigrations

Fields inherited from class org.apache.accumulo.server.master.balancer.TabletBalancer

context, TIME_BETWEEN_BALANCER_WARNINGS

Constructor Summary

Constructors

Constructor	Description
DefaultLoadBalancer()
DefaultLoadBalancer(TableId table)

Method Summary

Modifier and Type	Method	Description
long	balance(SortedMap<TServerInstance,TabletServerStatus> current, Set<KeyExtent> migrations, List<TabletMigration> migrationsOut)	Ask the balancer if any migrations are necessary.
TServerInstance	getAssignment(SortedMap<TServerInstance,TabletServerStatus> locations, TServerInstance last)
void	getAssignments(SortedMap<TServerInstance,TabletServerStatus> current, Map<KeyExtent,TServerInstance> unassigned, Map<KeyExtent,TServerInstance> assignments)	Assign tablets to tablet servers.
boolean	getMigrations(Map<TServerInstance,TabletServerStatus> current, List<TabletMigration> result)

Methods inherited from class org.apache.accumulo.server.master.balancer.TabletBalancer

checkMigrationSanity, constraintNotMet, getOnlineTabletsForTable, init, init, resetBalancerErrors

Methods inherited from class java.lang.Object

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

Field Detail

outstandingMigrations

protected final TabletBalancer.OutstandingMigrations outstandingMigrations

Constructor Detail

DefaultLoadBalancer

public DefaultLoadBalancer()

DefaultLoadBalancer

public DefaultLoadBalancer(TableId table)

Method Detail

getAssignment

public TServerInstance getAssignment(SortedMap<TServerInstance,TabletServerStatus> locations,
                                     TServerInstance last)

getMigrations

public boolean getMigrations(Map<TServerInstance,TabletServerStatus> current,
                             List<TabletMigration> result)

getAssignments

public void getAssignments(SortedMap<TServerInstance,TabletServerStatus> current,
                           Map<KeyExtent,TServerInstance> unassigned,
                           Map<KeyExtent,TServerInstance> assignments)

Description copied from class: TabletBalancer

Assign tablets to tablet servers. This method is called whenever the master finds tablets that are unassigned.

Specified by:

getAssignments in class TabletBalancer

Parameters:

current - The current table-summary state of all the online tablet servers. Read-only. The TabletServerStatus for each server may be null if the tablet server has not yet responded to a recent request for status.

unassigned - A map from unassigned tablet to the last known tablet server. Read-only.

assignments - A map from tablet to assigned server. Write-only.

balance

public long balance(SortedMap<TServerInstance,TabletServerStatus> current,
                    Set<KeyExtent> migrations,
                    List<TabletMigration> migrationsOut)

Description copied from class: TabletBalancer

Ask the balancer if any migrations are necessary. If the balancer is going to self-abort due to some environmental constraint (e.g. it requires some minimum number of tservers, or a maximum number of outstanding migrations), it should issue a log message to alert operators. The message should be at WARN normally and at ERROR if the balancer knows that the problem can not self correct. It should not issue these messages more than once a minute.

Specified by:

balance in class TabletBalancer

Parameters:

current - The current table-summary state of all the online tablet servers. Read-only.

migrations - the current set of migrations. Read-only.

migrationsOut - new migrations to perform; should not contain tablets in the current set of migrations. Write-only.

Returns:

the time, in milliseconds, to wait before re-balancing. This method will not be called when there are unassigned tablets.