org.apache.geode.cache.util

Class AutoBalancer

java.lang.Object

org.apache.geode.cache.util.AutoBalancer

All Implemented Interfaces:

Declarable

@Experimental(value="The autobalancer may be removed or the API may change in future releases")
public class AutoBalancer
extends java.lang.Object
implements Declarable

Re-balancing operation relocates data from heavily loaded members to lightly loaded members. In most cases, the decision to re-balance is based on the size of the member and a few other statistics. AutoBalancer monitors these statistics and if necessary, triggers a re-balancing request. Auto-Balancing is expected to prevent failures and data loss.

This implementation is based on Initializer implementation. By default auto-balancing is disabled. A user needs to configure AutoBalancer during cache initialization GemFireCache.getInitializer()

In a cluster only one member owns auto-balancing responsibility. This is achieved by grabbing a distributed lock. In case of a failure a new member will grab the lock and manage auto balancing.

AutoBalancer can be controlled using the following configurations

1. SCHEDULE
2. TBD THRESHOLDS

Field Summary

Fields

Modifier and Type	Field and Description
static java.lang.Object	AUTO_BALANCER_LOCK
static java.lang.String	AUTO_BALANCER_LOCK_SERVICE_NAME Name of the DistributedLockService that AutoBalancer will use to guard against concurrent maintenance activity
static int	DEFAULT_MINIMUM_SIZE Default value of MINIMUM_SIZE.
static int	DEFAULT_SIZE_THRESHOLD_PERCENT Default value of SIZE_THRESHOLD_PERCENT.
static java.lang.String	MINIMUM_SIZE In the initial data load phases, SIZE_THRESHOLD_PERCENT based rebalance invocation may be unnecessary.
static java.lang.String	SCHEDULE Use this configuration to manage out-of-balance audit frequency.
static java.lang.String	SIZE_THRESHOLD_PERCENT Use this configuration to manage re-balance invocation.

Constructor Summary

Constructors

Constructor and Description
AutoBalancer()
AutoBalancer(org.apache.geode.cache.util.AutoBalancer.AuditScheduler scheduler, org.apache.geode.cache.util.AutoBalancer.OOBAuditor auditor, org.apache.geode.cache.util.AutoBalancer.TimeProvider clock, org.apache.geode.cache.util.AutoBalancer.CacheOperationFacade cacheFacade)

Method Summary

Modifier and Type	Method and Description
void	destroy()
org.apache.geode.cache.util.AutoBalancer.CacheOperationFacade	getCacheOperationFacade()
void	init(java.util.Properties props) Initializes a user-defined object using the given properties.

Methods inherited from class java.lang.Object

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

Field Detail

SCHEDULE

public static final java.lang.String SCHEDULE

Use this configuration to manage out-of-balance audit frequency. If the auditor finds the system to be out-of-balance, it will trigger re-balancing. Any valid cron string is accepted. The sub-expressions represent the following:

1. Seconds
2. Minutes
3. Hours
4. Day-of-Month
5. Month
6. Day-of-Week
7. Year (optional field)

   For. e.g. 0 0 * * * ? for auditing the system every hour

See Also:

Constant Field Values

SIZE_THRESHOLD_PERCENT

public static final java.lang.String SIZE_THRESHOLD_PERCENT

Use this configuration to manage re-balance invocation. Rebalance operation will be triggered if the total number of bytes rebalance operation may move is more than this threshold, in percentage of the total data size.

Default value DEFAULT_SIZE_THRESHOLD_PERCENT

See Also:

Constant Field Values

DEFAULT_SIZE_THRESHOLD_PERCENT

public static final int DEFAULT_SIZE_THRESHOLD_PERCENT

Default value of SIZE_THRESHOLD_PERCENT. If 10% of data is misplaced, its a good time to redistribute buckets

See Also:

Constant Field Values

MINIMUM_SIZE

public static final java.lang.String MINIMUM_SIZE

In the initial data load phases, SIZE_THRESHOLD_PERCENT based rebalance invocation may be unnecessary. Rebalance should not be triggered if the total data size managed by cluster is too small. Rebalance operation will be triggered if the total number of bytes rebalance operation may move is more than this number of bytes.

Default value DEFAULT_MINIMUM_SIZE

See Also:

Constant Field Values

DEFAULT_MINIMUM_SIZE

public static final int DEFAULT_MINIMUM_SIZE

Default value of MINIMUM_SIZE. In the initial data load phases, SIZE_THRESHOLD_PERCENT based rebalance invocation may be unnecessary. Do not rebalance if the data to be moved is less than 100MB

See Also:

Constant Field Values

AUTO_BALANCER_LOCK_SERVICE_NAME

public static final java.lang.String AUTO_BALANCER_LOCK_SERVICE_NAME

Name of the DistributedLockService that AutoBalancer will use to guard against concurrent maintenance activity

See Also:

Constant Field Values

AUTO_BALANCER_LOCK

public static final java.lang.Object AUTO_BALANCER_LOCK

Constructor Detail

AutoBalancer

public AutoBalancer()

AutoBalancer

public AutoBalancer(org.apache.geode.cache.util.AutoBalancer.AuditScheduler scheduler,
                    org.apache.geode.cache.util.AutoBalancer.OOBAuditor auditor,
                    org.apache.geode.cache.util.AutoBalancer.TimeProvider clock,
                    org.apache.geode.cache.util.AutoBalancer.CacheOperationFacade cacheFacade)

Method Detail

init

public void init(java.util.Properties props)

Description copied from interface: Declarable

Initializes a user-defined object using the given properties. Note that any uncaught exception thrown by this method will cause the Cache initialization to fail.

Specified by:

init in interface Declarable

Parameters:

props - Contains the parameters declared in the declarative xml file.

getCacheOperationFacade

public org.apache.geode.cache.util.AutoBalancer.CacheOperationFacade getCacheOperationFacade()

destroy

public void destroy()