Timer for actor in quasar

Question

I have an actor, which I want to perform an action with delay, i.e. something like this (pseudocode):

void onReceive(message: Message){
    if (message is DelayedAction){
        sleep(100);
        preformSomeAction();
    }
    /*...*/
}

It is prudent to wait in another thread/strand while processing the other message, so I've added an ScheduledThreadPool for an actor:

ScheduledExecutorService executor = Executors.newScheduledThreadPool(0);

void onReceive(message: Message){
    if (message is DelayedAction){
        executor.schedule(sendMessageForAction, delay, TimeUnit.MILLISECONDS);
    }
    else if (message is MessageForAction){
        preformSomeAction();
    }
    /*...*/
}

So, waiting is performed in executor thread pool, and after that a message sent to actor.self to actually perform a task.

But sometimes messages are lost (only increasing number of threads in the pool helps). Now I'm not quite sure that I'm doing a right thing: may be quasar is not ok with threadPoolExecutors and I should use some other approach to delay action perform?

What is the right approach to delayed action on message receiving?

UPDATE:

One other option for me is to use fibers without pool:

void onReceive(message: Message){
    if (message is DelayedAction){
        new Fiber<V>() {
            @Override
            protected V run() throws SuspendExecution, InterruptedException {
                Strand.sleep(delay);
                sendMessageForAction();
            }
       }.start();
    }
    else if (message is MessageForAction){
        preformSomeAction();
    }
    /*...*/
}

I'm still not sure if it is the right way to go.