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| Webspshere MQ 7.0 JCA Adapter Transaction Rollback Issue |
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Message
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| Ravisankar_Challa |
 Posted: Thu Nov 18, 2010 6:35 am Post subject: Webspshere MQ 7.0 JCA Adapter Transaction Rollback Issue |
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Newbie
Joined: 18 Nov 2010
Posts: 3
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I developed a MDB3.0 using the JCA adapter that comes with MQ 7 which runs in Jboss App Server 5.0.2.
I am using Container Manged Transaction & Transaction Required.
5 messages are sent to MDB for testing.
let us consider the messages sent are
Message 1
Message 2
Message 3
Message 4
Message 5
Here is my code.
package com.example;
import javax.annotation.Resource;
import javax.ejb.ActivationConfigProperty;
import javax.ejb.MessageDriven;
import javax.ejb.MessageDrivenContext;
import javax.ejb.TransactionAttribute;
import javax.ejb.TransactionAttributeType;
import javax.ejb.TransactionManagement;
import javax.jms.JMSException;
import javax.jms.Message;
import javax.jms.MessageListener;
import javax.jms.TextMessage;
import org.jboss.ejb3.annotation.Pool;
import org.jboss.ejb3.annotation.ResourceAdapter;
@MessageDriven(
activationConfig = {
@ActivationConfigProperty(propertyName = "destinationType", propertyValue = "javax.jms.Queue"),
@ActivationConfigProperty(propertyName = "maxPoolDepth", propertyValue = "1"),
@ActivationConfigProperty(propertyName = "maxMessages", propertyValue = "1"),
@ActivationConfigProperty(propertyName = "useJNDI", propertyValue = "true"),
@ActivationConfigProperty(propertyName = "destination", propertyValue = "WMQ.INPUT.Q"),
@ActivationConfigProperty(propertyName = "readAheadAllowed", propertyValue = "DISABLED"),
@ActivationConfigProperty(propertyName = "messagingType", propertyValue = "javax.jms.MessageListener"),
})
@TransactionManagement(TransactionManagementType.CONTAINER)
@Pool(value="StrictMaxPool", maxSize=1, timeout=10000)
@ResourceAdapter(value="wmq.jmsra.rar")
public class Test implements MessageListener {
public Test() {
// TODO Auto-generated constructor stub
}
@Resource
MessageDrivenContext context;
@TransactionAttribute(TransactionAttributeType.REQUIRED)
public void onMessage(Message message) {
try {
System.out.println(((TextMessage)message).getText());
} catch (JMSException e) {
e.printStackTrace();
}
try {
throw new Exception("Exception");
} catch (Exception e) {
context.setRollbackOnly();
}
}
}
Output is:
Message 1
throw new Exception("Exception")
Message 2
throw new Exception("Exception")
Message 1
throw new Exception("Exception")
Message 2
throw new Exception("Exception")
Message 1
throw new Exception("Exception")
Message 2
throw new Exception("Exception")
....
ideally the output should always be message 1 if transaction rollback is proper..
I am expecting output to be
Message 1
throw new Exception("Exception")
Message 1
throw new Exception("Exception")
Message 1
throw new Exception("Exception")
Message 1
throw new Exception("Exception")
Is this a bug or am i missing something? |
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| Ravisankar_Challa |
| Posted: Fri Nov 19, 2010 7:05 pm Post subject: |
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Newbie
Joined: 18 Nov 2010
Posts: 3
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The MQ resource adapter version is
<resourceadapter-version>7.0.1.3-k701-103-100812</resourceadapter-version>
After analyzing for a long time i figured out something.
Initially when i deployed MDB consumer count on the queue is 1 (IPPROCS= 1). but when i send messages (IPPROCS is becoming 2). After some time it is coming back again to 1.
i set the following properties in mq resource adapter ra.xml
maxConnections = 1
connectionConcurrency = 1
Also in MDB
@ActivationConfigProperty(propertyName = "maxPoolDepth", propertyValue = "1"),
@ActivationConfigProperty(propertyName = "maxMessages", propertyValue = "1"),
@ActivationConfigProperty(propertyName = "readAheadAllowed", propertyValue = "DISABLED"),
to make (IPPROCS= 1) always.
still the consumer count is increased to two, my ultimate goal is to set a single consumer on queue. |
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| mqjeff |
| Posted: Fri Nov 19, 2010 7:48 pm Post subject: |
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Grand Master
Joined: 25 Jun 2008
Posts: 17447
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| IPPROCs is not the same thing as consumer threads, particularly with JMS listeners. |
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| fjb_saper |
| Posted: Fri Nov 19, 2010 8:24 pm Post subject: |
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Grand High Poobah
Joined: 18 Nov 2003
Posts: 20756
Location: LI,NY
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| mqjeff wrote: |
| IPPROCs is not the same thing as consumer threads, particularly with JMS listeners. |
 
@ravisankar: FYI with MDBs the max IPPROCS (if only the MDB is listening) is max number of MDB instances +1. So seeing an ipprocs of 2 for a single instance of MDB is not something to worry about. Have fun 
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MQ & Broker admin |
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| Ravisankar_Challa |
| Posted: Sat Nov 20, 2010 1:44 am Post subject: |
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Newbie
Joined: 18 Nov 2010
Posts: 3
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Thanks for the response. it made me clear now.
Now there is only one consumer, in this case if a transaction rollback happens after reading a message from the queue.
Ideally what should happen ?
Message will be put back to the top of the queue & the same message is consumed again. Is this correct?
In my case what i observed is if a transaction rollback occurs next message in the queue is consumed and the current message is put back on the top of the queue.
So the out of the mdb is
Message 1.
rollback
Message 2.
rollback.
Message 1.
rollback
Message 2.
rollback.
is this an expected behavior ?
Kindly help me is there any setting i need to change in the MQ resource adapter . |
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| Vitor |
| Posted: Sat Nov 20, 2010 4:56 am Post subject: |
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Grand High Poobah
Joined: 11 Nov 2005
Posts: 26093
Location: Texas, USA
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| Ravisankar_Challa wrote: |
| is this an expected behavior ? |
Unexpected but unsurprising. WMQ doesn't guarantee delivery sequence unless you request it at message put time by using grouping, and require such sequencing generally is called "message affinity" and is not best practice. A search of this forum will yield a wealth of discussion on this.
So you shouldn't rely on pure FIFO message delivery. I would imagine that message 2 has already been tagged as being the top of the queue when message 1 is read off (so that if a 2nd application does a get it received message 2). Clearly this pointer is not being moved when the rollback happens but shortly thereafter so the next get doesn't get the rollback message.
I'd welcome other theories (especially from those who know) but you shouldn't rely on getting the rolled back message on the next read.
(You should bear in mind that whichever message you get will be identified as rolled back correctly).
_________________
Honesty is the best policy.
Insanity is the best defence. |
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| fjb_saper |
| Posted: Sat Nov 20, 2010 6:49 am Post subject: |
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Grand High Poobah
Joined: 18 Nov 2003
Posts: 20756
Location: LI,NY
|
I believe this is expected behavior. If you check the specs there is a "reprocess interval" during which a rolled back message waits before getting processed again.
There is also a poll interval... What happens is that the system sets up a browse session that will feed it's content to the "onMessage" method of the MDB. This gets refreshed at poll interval, or if empty whenever a message hits the queue. Also the rollback will take some time. While it processes the next message is already being made available...
Have fun
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MQ & Broker admin |
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