In building a broad scalable application, one aspect we tend to lose is our ability to restrict and prevent concurrent activity. Within a single JVM we would use a synchronized lock to gatekeeper, a section of functionality from concurrent execution. Once we move away from a single JVM, this problem becomes a much bigger issue. Traditional approaches would leverage a transactional database to provide a system for locking, in the form of a table rowlock or transactional state. However, this approach presents us with a single point of failure and concurrency issues when scaling up our application.

Hazelcast offers a distributed locking facility, allowing us to attempt to acquire a cluster-wide named lock and to gatekeeper the functionality behind it. If we can create an example class LockingExample, we can demonstrate this ability.

public class LockingExample {
  public static void main(String[] args) throws Exception {
    HazelcastInstance hz = Hazelcast.newHazelcastInstance...