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Date: Thu, 11 Oct 2007 03:44:24 -0700 (PDT)
From: "Manu T George (JIRA)" <jira@apache.org>
To: dev@activemq.apache.org
Subject: [jira] Commented: (AMQ-1438) When in XA Transaction Active-MQ
 integrated with OpenEJB hangs in the isSameRM method of
 LocalAndXATransaction.
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    [ https://issues.apache.org/activemq/browse/AMQ-1438?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_40345 ] 

Manu T George commented on AMQ-1438:
------------------------------------

I believe I owe an explanation for the JIRA.

The problem faced is a hang in the method below when the Geronimo TM calls it.

   public boolean isSameRM(XAResource other) throws XAException {
       if (other instanceof WrapperNamedXAResource) {
           return
xaResource.isSameRM(((WrapperNamedXAResource)other).xaResource);
       }
       return false;
   }

The hang is because this method invokes org,apache.activemq.ActiveMQConnection.getResourceManagerId()

This method is shown below

    public String getResourceManagerId() throws JMSException {
        waitForBrokerInfo();
        if( brokerInfo==null )
            throw new JMSException("Connection failed before Broker info was received.");            
        return brokerInfo.getBrokerId().getValue();
    }

The waitForBrokerInfo() method is shown below

 private void waitForBrokerInfo() throws JMSException {
        try {
            brokerInfoReceived.await();
        } catch (InterruptedException e) {
            Thread.currentThread().interrupt();
            throw JMSExceptionSupport.create(e);
        }
    }

Once await is called on brokerInfoReceived which is a countdown latch currently brokerInfoReceived.countDown() never gets called. Actually this should get called on the 
else if ( command.isBrokerInfo() ) {
                this.brokerInfo = (BrokerInfo)command;
                brokerInfoReceived.countDown();
                this.optimizeAcknowledge &= !this.brokerInfo.isFaultTolerantConfiguration();
            }

block of the onCommand method of org.apache.activemq.ActiveMQConnection.

This is not getting called. 

On investigating and with some help from AMQ IRC , I found that there are two methods in org.apache.activemq.transport.vm.VMTransport. They are given below

    protected void syncOneWay(Object command){
        final TransportListener tl=peer.transportListener;
        prePeerSetQueue=peer.prePeerSetQueue;
        if(tl==null){
            prePeerSetQueue.add(command);
        }else{
            tl.onCommand(command);
        }
    }
    
    protected void asyncOneWay(Object command) throws IOException{
        messageQueue=getMessageQueue();
        try{
            messageQueue.put(command);
            wakeup();
        }catch(final InterruptedException e){
            log.error("messageQueue interupted",e);
            throw new IOException(e.getMessage());
        }
    }

The problem here is even when i set async=true for the VMTransport when the command BrokerInfo is sent syncOneWay is called. At that time TransportListener tl=null. So it gets added to prePeerSetQueue. The reason for this happening is that in org.apache.activemq.transport.vm.VMTransportFactory when the below lines are called a brokerInfo is sent as server.connect() is called. The async=true is not yet set resulting in the syncOneWay getting called. Only after that IntrospectionSupport.setProperties(vmtransport,options); is called and async is set to true. Due to this inconsistency the BrokerInfo command gets lost.

VMTransport vmtransport=server.connect();
IntrospectionSupport.setProperties(vmtransport,options);

I hope I made the issue clear. Can someone verify the patch or make a fix for this.


> When in XA Transaction Active-MQ integrated with OpenEJB hangs in the isSameRM method of LocalAndXATransaction. 
> ----------------------------------------------------------------------------------------------------------------
>
>                 Key: AMQ-1438
>                 URL: https://issues.apache.org/activemq/browse/AMQ-1438
>             Project: ActiveMQ
>          Issue Type: Bug
>          Components: Connector, Transport
>    Affects Versions: 4.1.1
>         Environment: All
>            Reporter: Manu T George
>            Priority: Critical
>             Fix For: 4.1.2
>
>         Attachments: AMQ-1438.patch
>
>
>  I was facing a problem with the AMQ 4.1 with the LocalAndXATransaction class's isSameRM waiting indefinitely. The wait is because waitForBrokerInfo calls brokerInfoReceived.await()
> where brokerInfoReceived is a countdown latch. Once this is waiting it
> never gets resumed.
> To trigger it the method onCommand(final Object o) has to be called on
> org.apache.activemq.ActiveMQConnection. 

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