[jboss-jira] [JBoss JIRA] Commented: (JBMESSAGING-1140) QueueReceiver starts out of sync with the server, so receiveNoWait always returns null

[Tim Fox (JIRA)]

    [ http://jira.jboss.com/jira/browse/JBMESSAGING-1140?page=comments#action_12386213 ] 
            
Tim Fox commented on JBMESSAGING-1140:
--------------------------------------

This is not a bug.

If you send a message to an empty queue and immediately call receiveNoWait() there is no guarantee you will receive that message.

According to the JMS spec it should "Receives the next message if one is immediately available.".

Just because you sent the message doesn't mean it's immediately available, there can be several reasons for this:

1) Non persistent messages are sent asynchronously to the server, so they'll possibly arrive sometime after the call to send() has returned.

2) JBM retrieves messages from a client side buffer. So the message needs to get from client->server. then from server->client buffer which is also asynchronous.

You'll find pretty much any messaging system (with the exception of JBoss MQ) works this way.

Having to make all message sends synchronous, and receiveNoWait to synchronously query the server each time would cripple performance and is not necessary anyway.

> QueueReceiver starts out of sync with the server, so receiveNoWait always returns null
> --------------------------------------------------------------------------------------
>
>                 Key: JBMESSAGING-1140
>                 URL: http://jira.jboss.com/jira/browse/JBMESSAGING-1140
>             Project: JBoss Messaging
>          Issue Type: Bug
>          Components: JMS Client Manager
>    Affects Versions: 1.4.0.SP1
>            Reporter: Carlo de Wolf
>         Assigned To: Tim Fox
>
> When there is a single message on the queue the browser will correctly report 1 message, but the receiver will not receive it right away.
>       QueueBrowser browser = session.createBrowser(queue);
>       Enumeration e = browser.getEnumeration();
>       List messages = CollectionsUtil.list(e);
>       QueueReceiver receiver = session.createReceiver(queue);
>       message = (TextMessage) receiver.receiveNoWait();
> 2007-11-06 13:58:06,437 TRACE [org.jboss.jms.client.JBossSession] attempting to create consumer for destination:JBossQueue[DLQ]
> 2007-11-06 13:58:06,438 TRACE [org.jboss.jms.client.delegate.DelegateSupport] SessionDelegate[1802245312, ID=c8a-r0sgfo8f-1-hnjqbo8f-ilci1t-110j3] invoking org.jboss.jms.wireformat.SessionCreateConsumerDelegateRequest at 2e7857a5 synchronously on server using Client[838449156]
> 2007-11-06 13:58:06,480 TRACE [org.jboss.jms.client.delegate.DelegateSupport] SessionDelegate[1802245312, ID=c8a-r0sgfo8f-1-hnjqbo8f-ilci1t-110j3] got server response for org.jboss.jms.wireformat.SessionCreateConsumerDelegateRequest at 2e7857a5: org.jboss.jms.wireformat.SessionCreateConsumerDelegateResponse at 1d30b5e2
> 2007-11-06 13:58:06,484 TRACE [org.jboss.jms.client.delegate.DelegateSupport] ConsumerDelegate[1910585900, ID=j8a-itsgfo8f-1-hnjqbo8f-ilci1t-110j3] invoking org.jboss.jms.wireformat.ConsumerChangeRateRequest at 79b2591c synchronously on server using Client[838449156]
> 2007-11-06 13:58:06,486 TRACE [org.jboss.jms.client.delegate.DelegateSupport] ConsumerDelegate[1910585900, ID=j8a-itsgfo8f-1-hnjqbo8f-ilci1t-110j3] got server response for org.jboss.jms.wireformat.ConsumerChangeRateRequest at 79b2591c: org.jboss.jms.wireformat.NullResponse at 468034b6
> 2007-11-06 13:58:06,488 TRACE [org.jboss.jms.client.container.ClientConsumer] ClientConsumer[j8a-itsgfo8f-1-hnjqbo8f-ilci1t-110j3] receiving, timeout = -1
> 2007-11-06 13:58:06,488 TRACE [org.jboss.jms.client.container.ClientConsumer] ClientConsumer[j8a-itsgfo8f-1-hnjqbo8f-ilci1t-110j3]: receive, noWait
> 2007-11-06 13:58:06,488 TRACE [org.jboss.jms.client.container.ClientConsumer] ClientConsumer[j8a-itsgfo8f-1-hnjqbo8f-ilci1t-110j3]: no message available
> 2007-11-06 13:58:06,545 TRACE [org.jboss.jms.client.container.ClientConsumer] org.jboss.jms.client.container.ClientConsumer$HandleMessageRunnable at 66201d6d receiving message delegator->JBossMessage[58368]:PERSISTENT, deliveryId=1 from the remoting layer
> 2007-11-06 13:58:06,545 TRACE [org.jboss.jms.client.container.ClientConsumer] org.jboss.jms.client.container.ClientConsumer$HandleMessageRunnable at 66201d6d added message(s) to the buffer are now 1 messages

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