Distributed Execution
Distributed executor service is a distributed implementation of java.util.concurrent.ExecutorService. It allows you to execute your code in the cluster. In this chapter, all the code samples are based on the Echo class above. Please note that Echo class is Serializable . You can ask Hazelcast to execute your code (Runnable, Callable);
on a specific cluster member you choose,
on the member owning the key you choose,
on the member Hazelcast will pick, and
on all or subset of the cluster members.
import com.hazelcast.core.Member;
import com.hazelcast.core.Hazelcast;
import com.hazelcast.core.IExecutorService;
import java.util.concurrent.Callable;
import java.util.concurrent.Future;
import java.util.Set;
import com.hazelcast.config.Config;
public void echoOnTheMember(String input, Member member) throws Exception {
Callable<String> task = new Echo(input);
HazelcastInstance hz = Hazelcast.newHazelcastInstance();
IExecutorService executorService = hz.getExecutorService("default");
Future<String> future = executorService.submitToMember(task, member);
String echoResult = future.get();
}
public void echoOnTheMemberOwningTheKey(String input, Object key) throws Exception {
Callable<String> task = new Echo(input);
HazelcastInstance hz = Hazelcast.newHazelcastInstance();
IExecutorService executorService = hz.getExecutorService("default");
Future<String> future = executorService.submitToKeyOwner(task, key);
String echoResult = future.get();
}
public void echoOnSomewhere(String input) throws Exception {
HazelcastInstance hz = Hazelcast.newHazelcastInstance();
IExecutorService executorService = hz.getExecutorService("default");
Future<String> future = executorService.submit(new Echo(input));
String echoResult = future.get();
}
public void echoOnMembers(String input, Set<Member> members) throws Exception {
HazelcastInstance hz = Hazelcast.newHazelcastInstance();
IExecutorService executorService = hz.getExecutorService("default");
Map<Member, Future<String>> futures = executorService.submitToMembers(new Echo(input), members);
for (Future<String> future : futures.values()) {
String echoResult = future.get();
// ...
}
}
Note that you can obtain the set of cluster members via Hazelcast.getCluster().getMembers() call.