Distributed locking

When building a broad, horizontally scaled application, one aspect that we tend to lose is the ability to restrict and prevent concurrent activity across the whole application. Within a single JVM, we use a synchronized lock to guard a section of functionality from a 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 a transactional state. However, this approach presents us with a single point of failure and contention issues when scaling up our application.

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

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