Distributed lock with Hazelcast not working

Question

I am trying to test my distributed lock implementation but I still haven't found a way to make it work. I deployed a REST service with two simple methods, like this:

@GET
@Path("/lock")
@Produces("text/*")
public String lock() throws InterruptedException {
    Lock lock = distributedService.getDistributedLock("test");
    boolean result = lock.tryLock(5, TimeUnit.SECONDS);
    return result ? "locked" : "timeout";
}

@GET
@Path("/unlock")
@Produces("text/*")
public String unlock() {
    Lock lock = distributedService.getDistributedLock("test");
    lock.unlock();
    return "unlocked";
}

The distributedService object implements the getDistributedLock() method:

@Override
public Lock getDistributedLock(String lockName) {
    return Hazelcast.getDefaultInstance().getLock(lockName);
}

In the hazelcast.xml file, I enabled TCP-IP connection and disabled everything else:

<network>
<port auto-increment="true">5701</port>
<join>
  <multicast enabled="false" />
  <tcp-ip enabled="true">
    <interface>192.168.0.01</interface>
    <interface>192.168.0.02</interface>
  </tcp-ip>
</join>
<interfaces enabled="false" />
<symmetric-encryption enabled="false" />
<asymmetric-encryption enabled="false" />

I deployed the application in the two machines, with IP adresses corresponding to the .xml file (192.168.0.01 and 192.168.0.02) and when I call the service from the browser It works for the first time (it locks and returns "locked") and everytime I call the unlock() method it returns correctly (I get the string "unlocked") but after the first time, everytime that I call the lock() method I get a timeout. It doesn't look like the unlock() method is unlocking it.

Can someone point me the correct way to use Distributed Lock with hazelcast?

Answer 1

Only the thread that locked can unlock it. You are saying that you have implemented REST for lock and unlock. And I guess the thread that locks and unlocks are different. That's why it is not working. Try to print the Thread name and see yourself.