RacyUpdateMember.java

import com.hazelcast.core.Hazelcast;
import com.hazelcast.core.HazelcastInstance;
import com.hazelcast.core.IMap;

import java.io.Serializable;

public class RacyUpdateMember {

    public static void main(String[] args) throws Exception {
        HazelcastInstance hz = Hazelcast.newHazelcastInstance();
        IMap<String, Value> map = hz.getMap("map");
        String key = "1";
        map.put(key, new Value());
        System.out.println("Starting");
        for (int i = 0; i < 1000; i++) {
            if (i % 100 == 0) {
                System.out.println("At: " + i);
            }
            Value value = map.get(key);
            Thread.sleep(10);
            value.amount++;
            map.put(key, value);
        }
        System.out.println("Finished! Result = " + map.get(key).amount);

        Hazelcast.shutdownAll();
    }

    static final class Value implements Serializable {

        private int amount;
    }
}