com.hazelcast.config

Class PartitionGroupConfig

java.lang.Object

com.hazelcast.config.PartitionGroupConfig

public class PartitionGroupConfig
extends Object

With PartitionGroupConfig, you can control how primary and backup partitions are mapped to physical Members.

Hazelcast will always place partitions on different partition groups so as to provide redundancy. There are seven partition group schemes defined in PartitionGroupConfig.MemberGroupType: PER_MEMBER, HOST_AWARE CUSTOM, ZONE_AWARE, NODE_AWARE, PLACEMENT_AWARE, SPI.

In all cases a partition will never be created on the same group. If there are more partitions defined than there are partition groups, then only those partitions, up to the number of partition groups, will be created. For example, if you define 2 backups, then with the primary, that makes 3. If you have only two partition groups only two will be created.

PER_MEMBER Partition Groups

This is the default partition scheme and is used if no other scheme is defined. Each Member is in a group of its own.

Partitions (primaries and backups) will be distributed randomly but not on the same Member.

 <partition-group enabled="true" group-type="PER_MEMBER"/>
 

This provides good redundancy when Members are on separate hosts but not if multiple instances are being run from the same host.

HOST_AWARE Partition Groups

In this scheme, a group corresponds to a host, based on its IP address. Partitions will not be written to any other members on the same host.

This scheme provides good redundancy when multiple instances are being run on the same host.

 <partition-group enabled="true" group-type="HOST_AWARE"/>
 

CUSTOM Partition Groups

In this scheme, IP addresses, or IP address ranges, are allocated to groups. Partitions are not written to the same group. This is very useful for ensuring partitions are written to different racks or even availability zones.

For example, members in data center 1 have IP addresses in the range 10.10.1.* and for data center 2 they have the IP address range 10.10.2.*. You would achieve HA by configuring a CUSTOM partition group as follows:

 <partition-group enabled="true" group-type="CUSTOM">
      <member-group>
          <interface>10.10.1.*</interface>
      </member-group>
      <member-group>
          <interface>10.10.2.*</interface>
      </member-group>
 </partition-group>
 

The interfaces can be configured with wildcards ('*') and also with address ranges e.g. '10-20'. Each member-group can have an unlimited number of interfaces.

You can define as many member-groups as you want. Hazelcast will always store backups in a different member-group to the primary partition.

ZONE_AWARE Partition Groups

In this scheme, groups are allocated according to the metadata provided by Discovery SPI. These metadata are availability zone, rack and host. The backups of the partitions are not placed on the same group so this is very useful for ensuring partitions are placed on different availability zones without providing the IP addresses to the config ahead.

 <partition-group enabled="true" group-type="ZONE_AWARE"/>
 

NODE_AWARE Partition Groups

In this scheme, groups are allocated according to node name metadata provided by Discovery SPI. For container orchestration tools like Kubernetes and Docker Swarm, node is the term used to refer machine that containers/pods run on. A node may be a virtual or physical machine. The backups of the partitions are not placed on same group so this is very useful for ensuring partitions are placed on different nodes without providing the IP addresses to the config ahead.

 <partition-group enabled="true" group-type="NODE_AWARE"/>
 

PLACEMENT_AWARE Partition Groups

In this scheme, groups are allocated according to the placement metadata provided by Discovery SPI. Depending on the cloud provider, this metadata indicates the placement information (rack, fault domain, etc.) of a VM in a zone. This scheme provides a finer granularity than ZONE_AWARE for partition groups and is useful to provide good redundancy when running members within a single availability zone.

 <partition-group enabled="true" group-type="PLACEMENT_AWARE"/>
 

SPI Aware Partition Groups

In this scheme, groups are allocated according to the implementation provided by Discovery SPI.

 <partition-group enabled="true" group-type="SPI"/>
 

Overlapping Groups

Care should be taken when selecting overlapping groups, e.g.

 <partition-group enabled="true" group-type="CUSTOM">
      <member-group>
          <interface>10.10.1.1</interface>
          <interface>10.10.1.2</interface>
      </member-group>
      <member-group>
          <interface>10.10.1.1</interface>
          <interface>10.10.1.3</interface>
      </member-group>
 </partition-group>
 

In this example there are 2 groups, but because interface 10.10.1.1 is shared between the 2 groups, this member may store store primary and backups.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	PartitionGroupConfig.MemberGroupType Type of member groups.

Constructor Summary

Constructors

Constructor and Description
PartitionGroupConfig()

Method Summary

Modifier and Type	Method and Description
PartitionGroupConfig	addMemberGroupConfig(MemberGroupConfig memberGroupConfig) Adds a MemberGroupConfig.
PartitionGroupConfig	clear() Removes all the PartitionGroupConfig.MemberGroupType instances.
boolean	equals(Object o)
PartitionGroupConfig.MemberGroupType	getGroupType() Returns the MemberGroupType configured.
Collection<MemberGroupConfig>	getMemberGroupConfigs() Returns an unmodifiable collection containing all MemberGroupConfig elements.
int	hashCode()
boolean	isEnabled() Checks if this PartitionGroupConfig is enabled.
PartitionGroupConfig	setEnabled(boolean enabled) Enables or disables this PartitionGroupConfig.
PartitionGroupConfig	setGroupType(PartitionGroupConfig.MemberGroupType memberGroupType) Sets the MemberGroupType.
PartitionGroupConfig	setMemberGroupConfigs(Collection<MemberGroupConfig> memberGroupConfigs) Adds a MemberGroupConfig.
String	toString()

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

PartitionGroupConfig

public PartitionGroupConfig()

Method Detail

isEnabled

public boolean isEnabled()

Checks if this PartitionGroupConfig is enabled.

Returns:

true if this PartitionGroupConfig is enabled, false otherwise

setEnabled

public PartitionGroupConfig setEnabled(boolean enabled)

Enables or disables this PartitionGroupConfig.

Parameters:

enabled - true to enable, false to disable

Returns:

the updated PartitionGroupConfig

getGroupType

public PartitionGroupConfig.MemberGroupType getGroupType()

Returns the MemberGroupType configured. Could be null if no MemberGroupType has been configured.

Returns:

the MemberGroupType

setGroupType

public PartitionGroupConfig setGroupType(PartitionGroupConfig.MemberGroupType memberGroupType)

Sets the MemberGroupType. A @{link MemberGroupType#CUSTOM} indicates that custom groups are created. With the PartitionGroupConfig.MemberGroupType.HOST_AWARE group type, Hazelcast makes a group for every host, that prevents a single host containing primary and backup. See the MemberGroupConfig for more information.

Parameters:

memberGroupType - the MemberGroupType to set

Returns:

the updated PartitionGroupConfig

Throws:

IllegalArgumentException - if memberGroupType is null

See Also:

getGroupType()

addMemberGroupConfig

public PartitionGroupConfig addMemberGroupConfig(MemberGroupConfig memberGroupConfig)

Adds a MemberGroupConfig. Duplicate elements are not filtered.

Parameters:

memberGroupConfig - the MemberGroupConfig to add

Returns:

the updated PartitionGroupConfig

Throws:

IllegalArgumentException - if memberGroupConfig is null

See Also:

addMemberGroupConfig(MemberGroupConfig)

getMemberGroupConfigs

public Collection<MemberGroupConfig> getMemberGroupConfigs()

Returns an unmodifiable collection containing all MemberGroupConfig elements.

Returns:

an unmodifiable collection containing all MemberGroupConfig elements

See Also:

setMemberGroupConfigs(java.util.Collection)

clear

public PartitionGroupConfig clear()

Removes all the PartitionGroupConfig.MemberGroupType instances.

Returns:

the updated PartitionGroupConfig

See Also:

setMemberGroupConfigs(java.util.Collection)

setMemberGroupConfigs

public PartitionGroupConfig setMemberGroupConfigs(Collection<MemberGroupConfig> memberGroupConfigs)

Adds a MemberGroupConfig. This MemberGroupConfig only has meaning when the group-type is set to PartitionGroupConfig.MemberGroupType.CUSTOM. See the PartitionGroupConfig for more information and examples of how this mechanism works.

Parameters:

memberGroupConfigs - the collection of MemberGroupConfig to add

Returns:

the updated PartitionGroupConfig

Throws:

IllegalArgumentException - if memberGroupConfigs is null

See Also:

getMemberGroupConfigs(), clear(), addMemberGroupConfig(MemberGroupConfig)

equals

public final boolean equals(Object o)

Overrides:

equals in class Object

hashCode

public final int hashCode()

Overrides:

hashCode in class Object

toString

public String toString()

Overrides:

toString in class Object