KeepAlive timer in shared file lock doesn't detect lock deletion in time

I have AMQ running on openstack with following persistence configuration.

<persistenceAdapter>
    <kahaDB directory="/mnt/nfs/fuse-shared/kahadb" lockKeepAlivePeriod="2000">
        <locker>
            <shared-file-locker lockAcquireSleepInterval="10000"/>
        </locker>
    </kahaDB>
</persistenceAdapter>

Where location /mnt/nfs/fuse-shared/ is NFSv4 share.

When I delete lock file the broker should stop in keepalive period (2s). But it works only when I delete lock on the machine, where broker is running.

If I delete lock file from another machine which has same NFS mounted then it takes broker up to 60 seconds before broker realizes that the lock file was deleted.

If I delete lock from another machine and then ssh into machine where broker is running and just list the kahaDB directory:

ls /mnt/nfs/fuse-shared/kahadb/ 

Then keepAlive detects file deletion and broker shutdown in 2s.