Question

I would like to use this library I found, it’s a pure java port (not a wrapper) of zeromq.
I am trying to test it and while it claims some good numbers, the test I am performing is giving rather poor results and it’s even performed locally (client and serve on the same machine). I’m sure it’s something I am doing wrong. It takes approx. 5 seconds to execute this 10.000 messages loop.

All I did is take the Hello world example and removed pause and sysouts. Here is the code:

The Server:

package guide;

import org.jeromq.ZMQ;

public class hwserver{
    public static void main(String[] args) throws Exception{

        //  Prepare our context and socket
        ZMQ.Context context = ZMQ.context(1);
        ZMQ.Socket socket = context.socket(ZMQ.REP);

        System.out.println("Binding hello world server");
        socket.bind ("tcp://*:5555");        

        while (true) {                  
            byte[] reply = socket.recv(0);
            String requestString = "Hello" ;
            byte[] request = requestString.getBytes();              
            socket.send(request, 0);            
        }              
    }
}

The Client:

package guide;

import org.jeromq.ZMQ;

public class hwclient{
    public static void main(String[] args){
        ZMQ.Context context = ZMQ.context(1);
        ZMQ.Socket socket = context.socket(ZMQ.REQ);
        socket.connect ("tcp://localhost:5555");

        System.out.println("Connecting to hello world server");

        long start = System.currentTimeMillis();
        for(int request_nbr = 0; request_nbr != 10_000; request_nbr++) {
            String requestString = "Hello" ;
            byte[] request = requestString.getBytes();           
            socket.send(request, 0);
            byte[] reply = socket.recv(0);           
        }
        long end = System.currentTimeMillis();
        System.out.println(end-start);
        socket.close();
        context.term();
    }
}

Is is possible to fix this code and get some decent numbers?

Answer 1

You’re doing round-trip request-reply, and this will be just as slow using the C++ libzmq. You will only get fast performance on JeroQM, ZeroMQ, or any I/O when you do streaming.

Round-tripping is slow due to how I/O and TCP work. On libzmq we can do about 20K messages/second using round-tripping, and 8M/sec using streaming. Streaming has additional optimizations like batching which you can’t do with round-trip request-reply.

For a throughput performance test, send 10M messages from node 1 to node 2, then send back a single ACK when you get them. Time that on ZeroMQ and on JeroMQ, you should see around 3x difference in speed.