zeromq route-req java example does not work - request

Question

I run this official Java example in Eclipse, with jeromq-0.3.2.jar library, it doesn't work if I "run" it, it only works if I set some break point and "debug" it.
It seems the message is lost. My own application using route-req pattern has this problem too.
This is their official example, if this doesn't work, what can? can someone try it and figure out why?
http://zguide.zeromq.org/java:rtreq
or codes are here:
import org.zeromq.ZMQ;
import org.zeromq.ZMQ.Context;
import org.zeromq.ZMQ.Socket;
import java.util.Random;
/**
* ROUTER-TO-REQ example
*/
public class rtreq
{
private static Random rand = new Random();
private static final int NBR_WORKERS = 10;
private static class Worker extends Thread {
#Override
public void run() {
Context context = ZMQ.context(1);
Socket worker = context.socket(ZMQ.REQ);
ZHelper.setId (worker); // Set a printable identity
worker.connect("tcp://localhost:5671");
int total = 0;
while (true) {
// Tell the broker we're ready for work
worker.send ("Hi Boss");
// Get workload from broker, until finished
String workload = worker.recvStr ();
boolean finished = workload.equals ("Fired!");
if (finished) {
System.out.printf ("Completed: %d tasks\n", total);
break;
}
total++;
// Do some random work
try {
Thread.sleep (rand.nextInt (500) + 1);
} catch (InterruptedException e) {
}
}
worker.close();
context.term();
}
}
/**
* While this example runs in a single process, that is just to make
* it easier to start and stop the example. Each thread has its own
* context and conceptually acts as a separate process.
*/
public static void main (String[] args) throws Exception {
Context context = ZMQ.context(1);
Socket broker = context.socket(ZMQ.ROUTER);
broker.bind("tcp://*:5671");
for (int workerNbr = 0; workerNbr < NBR_WORKERS; workerNbr++)
{
Thread worker = new Worker ();
worker.start ();
}
// Run for five seconds and then tell workers to end
long endTime = System.currentTimeMillis () + 5000;
int workersFired = 0;
while (true) {
// Next message gives us least recently used worker
String identity = broker.recvStr ();
broker.sendMore (identity);
broker.recvStr (); // Envelope delimiter
broker.recvStr (); // Response from worker
broker.sendMore ("");
// Encourage workers until it's time to fire them
if (System.currentTimeMillis () < endTime)
broker.send ("Work harder");
else {
broker.send ("Fired!");
if (++workersFired == NBR_WORKERS)
break;
}
}
broker.close();
context.term();
}
}

Answer 1

To make this example works, you need to be sure that each worker has unique id.
As an example, I removed
ZHelper.setId (worker); // Set a printable identity
and add a constructor to Worker class with workerId string.
Result:
import org.zeromq.ZMQ;
import java.util.Random;
/**
* ROUTER-TO-REQ example
*/
public class rtreq {
private static Random rand = new Random();
private static final int NBR_WORKERS = 10;
private static class Worker extends Thread {
private String workerId;
Worker(String workerId) {
this.workerId = workerId;
}
#Override
public void run() {
ZMQ.Context context = ZMQ.context(1);
ZMQ.Socket worker = context.socket(ZMQ.REQ);
worker.setIdentity(workerId.getBytes());
worker.connect("tcp://localhost:5671");
int total = 0;
while (true) {
// Tell the broker we're ready for work
worker.send("Hi Boss");
// Get workload from broker, until finished
String workload = worker.recvStr();
boolean finished = workload.equals("Fired!");
if (finished) {
System.out.printf(workerId + " completed: %d tasks\n", total);
break;
}
total++;
// Do some random work
try {
Thread.sleep(rand.nextInt(500) + 1);
} catch (InterruptedException e) {
}
}
worker.close();
context.term();
}
}
/**
* While this example runs in a single process, that is just to make
* it easier to start and stop the example. Each thread has its own
* context and conceptually acts as a separate process.
*/
public static void main(String[] args) throws Exception {
ZMQ.Context context = ZMQ.context(1);
ZMQ.Socket broker = context.socket(ZMQ.ROUTER);
broker.bind("tcp://*:5671");
// starting all workers
for (int workerNbr = 0; workerNbr < NBR_WORKERS; workerNbr++) {
Thread worker = new Worker("worker-" + workerNbr);
worker.start();
}
// Run for five seconds and then tell workers to end
long endTime = System.currentTimeMillis() + 5000;
int workersFired = 0;
while (true) {
// Next message gives us least recently used worker
String identity = broker.recvStr();
broker.sendMore(identity);
broker.recvStr(); // Envelope delimiter
broker.recvStr(); // Response from worker
broker.sendMore("");
// Encourage workers until it's time to fire them
if (System.currentTimeMillis() < endTime)
broker.send("Work harder");
else {
broker.send("Fired!");
if (++workersFired == NBR_WORKERS)
break;
}
}
broker.close();
context.term();
}
}
System out:
worker-2 completed: 27 tasks
worker-3 completed: 20 tasks
worker-8 completed: 24 tasks
worker-6 completed: 23 tasks
worker-0 completed: 20 tasks
worker-9 completed: 21 tasks
worker-7 completed: 20 tasks
worker-5 completed: 21 tasks
worker-4 completed: 19 tasks
worker-1 completed: 25 tasks