You must not rely on receiveNoWait to always return a message. What the method does is check whether any messages have been dispatched to the consumer AND are *waiting on the consumer's prefetch* This is not the case in your test above as it takes a few cycles for the broker to dispatch over your network to get to the consumer's prefetch.
Please do a search of the list ahead of time as this has been succinctly answered before by Tim: http://activemq.2283324.n4.nabble.com/consumer-receiveNoWait-question-td4656435.html#a4656615 This behavior follows the JMS spec, but I realize different providers may have implemented this differently, so if you try with prefetch == 0 on the consumer side, it should actively poll the broker ... which is probably what you're looking for. On Fri, Sep 27, 2013 at 7:38 AM, zbc <zhebinc...@163.com> wrote: > please run following test: > > *package com.conceptwave.servicedesigner; > > import java.util.Hashtable; > > import javax.jms.JMSException; > import javax.jms.Message; > import javax.jms.Queue; > import javax.jms.QueueConnection; > import javax.jms.QueueConnectionFactory; > import javax.jms.QueueReceiver; > import javax.jms.QueueSender; > import javax.jms.QueueSession; > import javax.jms.Session; > import javax.naming.Context; > import javax.naming.InitialContext; > import javax.naming.NamingException; > > import junit.framework.Assert; > > import org.junit.Before; > import org.junit.Test; > > public class test { > /** > * put a test message to queue before test case run. > */ > @Before > public void setup() { > InitialContext ctx = null; > QueueConnection con = null; > QueueSession queueSession = null; > QueueSender sender = null; > try { > Hashtable env = new Hashtable(); > env = new Hashtable(); > env.put(Context.INITIAL_CONTEXT_FACTORY, > > "org.apache.activemq.jndi.ActiveMQInitialContextFactory"); > env.put(Context.PROVIDER_URL, > "tcp://localhost:61616"); > ctx = new InitialContext(env); > QueueConnectionFactory fac = > (QueueConnectionFactory) ctx > .lookup("ConnectionFactory"); > con = fac.createQueueConnection(); > queueSession = con.createQueueSession(false, > Session.AUTO_ACKNOWLEDGE); > con.start(); > sender = queueSession.createSender((Queue) ctx > .lookup("dynamicQueues/queue1")); > sender.send(queueSession.createTextMessage("test > message")); > } catch (Exception e) { > e.printStackTrace(); > } finally { > try { > sender.close(); > queueSession.close(); > con.close(); > ctx.close(); > } catch (JMSException e) { > // TODO Auto-generated catch block > e.printStackTrace(); > } catch (NamingException e) { > // TODO Auto-generated catch block > e.printStackTrace(); > } > } > } > > /** > * the receiver must sleep enough time after it is created in > order to > * receive the message in the queue. > */ > @Test > public void test1() { > InitialContext ctx = null; > QueueConnection con = null; > QueueSession queueSession = null; > QueueReceiver receiver = null; > try { > Hashtable env = new Hashtable(); > env = new Hashtable(); > env.put(Context.INITIAL_CONTEXT_FACTORY, > > "org.apache.activemq.jndi.ActiveMQInitialContextFactory"); > env.put(Context.PROVIDER_URL, > "tcp://localhost:61616"); > ctx = new InitialContext(env); > QueueConnectionFactory fac = > (QueueConnectionFactory) ctx > .lookup("ConnectionFactory"); > con = fac.createQueueConnection(); > queueSession = con.createQueueSession(false, > Session.AUTO_ACKNOWLEDGE); > con.start(); > receiver = queueSession.createReceiver((Queue) ctx > .lookup("dynamicQueues/queue1")); > > // in order to receive the message from queue, > must sleep enough > // time > Thread.sleep(500); > // the message can be received successfully after > sleep. > Message result = receiver.receiveNoWait(); > Assert.assertNotNull(result); > } catch (Exception e) { > e.printStackTrace(); > } finally { > try { > receiver.close(); > queueSession.close(); > con.close(); > ctx.close(); > } catch (JMSException e) { > // TODO Auto-generated catch block > e.printStackTrace(); > } catch (NamingException e) { > // TODO Auto-generated catch block > e.printStackTrace(); > } > } > } > > /** > * the receiver never get the message IMMEDIATELY after it is > created. > * > * @throws Exception > * to junit. > */ > @Test > public void test2() throws Exception { > // sleep enough time to make sure the test message is > really put into > // the queue. > Thread.sleep(5000); > > InitialContext ctx = null; > QueueConnection con = null; > QueueSession queueSession = null; > QueueReceiver receiver = null; > try { > Hashtable env = new Hashtable(); > env = new Hashtable(); > env.put(Context.INITIAL_CONTEXT_FACTORY, > > "org.apache.activemq.jndi.ActiveMQInitialContextFactory"); > env.put(Context.PROVIDER_URL, > "tcp://localhost:61616"); > > // repeatedly try to receive message, but you > NEVER get it!! > for (int i = 0; i < 100; i++) { > ctx = new InitialContext(env); > QueueConnectionFactory fac = > (QueueConnectionFactory) ctx > > .lookup("ConnectionFactory"); > con = fac.createQueueConnection(); > queueSession = > con.createQueueSession(false, > Session.AUTO_ACKNOWLEDGE); > con.start(); > receiver = > queueSession.createReceiver((Queue) ctx > > .lookup("dynamicQueues/queue1")); > // no sleep after the receiver is created > // Thread.sleep(500); > Message result = receiver.receiveNoWait(); > // you CAN NOT get the message in the > queue. > Assert.assertNull(result); > } > } catch (Exception e) { > e.printStackTrace(); > } finally { > try { > receiver.close(); > queueSession.close(); > con.close(); > ctx.close(); > } catch (JMSException e) { > // TODO Auto-generated catch block > e.printStackTrace(); > } catch (NamingException e) { > // TODO Auto-generated catch block > e.printStackTrace(); > } > } > } > > }* > > > > > -- > View this message in context: > http://activemq.2283324.n4.nabble.com/standard-jms-code-can-not-receive-message-from-queue-tp4671868p4671901.html > Sent from the ActiveMQ - User mailing list archive at Nabble.com. > -- *Christian Posta* http://www.christianposta.com/blog twitter: @christianposta
