CODEWITHSUNDEEP
javamultithreadinghazelcast
Dmytro Titov
Dmytro Titov

Reputation: 3201

Hazelcast: number of threads on a cluster with multi CPU machines

I made a cluster using Hazelcast: it has one master node that spreads Runnables among 5 other nodes. My question is: does Hazelcast ExecuterService perform computations within each computing node also in parallel?

I mean, if each of my computing nodes have 4 CPUs (or 4 cores on a single CPU), what will be the total number of threads participating in computations? 5 (thread per node) or 5*4=20 (thread per CPU/core)?

Upvotes: 0

Views: 701

Answers (2)

Dmytro Titov
Dmytro Titov

Reputation: 3201

Well, we can figutre it out manually:

public class HazelcastTest {

    @Test
    public void test() {
        HazelcastInstance instance = Hazelcast.newHazelcastInstance();

        IExecutorService exec = instance.getExecutorService("exec");
        for (int i = 0; i < 100; i++) {
            exec.submit(new MyRunnable());
        }
    }

}

public class MyRunnable implements Runnable, Serializable {

    @Override
    public void run() {
        long threadId = Thread.currentThread().getId();
        System.err.println("threadId: " + threadId);
    }

}

The result is:

threadId: 48
threadId: 48
threadId: 46
threadId: 48
threadId: 46
threadId: 48
threadId: 46
threadId: 46
threadId: 54
threadId: 48
...etc...

Another proof is that CPU monitor shows 100% load for all available cores.

Upvotes: 0

ali
ali

Reputation: 886

your runnable sent to the member will run once per member, which means it will use only single thread. So 5

Upvotes: 1

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