Member Attributes

You can define various member attributes on your Hazelcast members. You can use these member attributes to tag your members as your business logic requirements.

In order to define member attribute on a member you can either:

  • provide MemberAttributeConfig to your Config object,

  • or provide member attributes at runtime via attribute setter methods on the Member interface.

For example, you can tag your members with their CPU characteristics and you can route CPU intensive tasks to those CPU-rich members.

MemberAttributeConfig fourCore = new MemberAttributeConfig();
memberAttributeConfig.setIntAttribute( "CPU_CORE_COUNT", 4 );
MemberAttributeConfig twelveCore = new MemberAttributeConfig();
memberAttributeConfig.setIntAttribute( "CPU_CORE_COUNT", 12 );
MemberAttributeConfig twentyFourCore = new MemberAttributeConfig();
memberAttributeConfig.setIntAttribute( "CPU_CORE_COUNT", 24 );

Config member1Config = new Config();
config.setMemberAttributeConfig( fourCore );
Config member2Config = new Config();
config.setMemberAttributeConfig( twelveCore );
Config member3Config = new Config();
config.setMemberAttributeConfig( twentyFourCore );

HazelcastInstance member1 = Hazelcast.newHazelcastInstance( member1Config );
HazelcastInstance member2 = Hazelcast.newHazelcastInstance( member2Config );
HazelcastInstance member3 = Hazelcast.newHazelcastInstance( member3Config );

IExecutorService executorService = member1.getExecutorService( "processor" );

executorService.execute( new CPUIntensiveTask(), new MemberSelector() {
  public boolean select(Member member) {
    int coreCount = (int) member.getIntAttribute( "CPU_CORE_COUNT" );
    // Task will be executed at either member2 or member3
    if ( coreCount > 8 ) { 
      return true;
    return false;
} );

HazelcastInstance member4 = Hazelcast.newHazelcastInstance();
// We can also set member attributes at runtime.
member4.setIntAttribute( "CPU_CORE_COUNT", 2 );