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From "Rajith Attapattu (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (QPID-3234) Exception handling logic is incorrect in AMQConnection.java
Date Thu, 19 May 2011 18:56:47 GMT

    [ https://issues.apache.org/jira/browse/QPID-3234?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13036371#comment-13036371
] 

Rajith Attapattu commented on QPID-3234:
----------------------------------------

The AMQP spec defines Connection errors as hard errors and Execution (Session) exceptions
as soft errors.
So there is no question about how to determine if it's a hard error or not.

Unfortunately JMS does not have a session level exception listener to notify errors if the
client is in a passive mode.
Ex. When using a message listener.
Therefore as explained above in some cases a session error is infact a serious issue that
has to be notified and the only way to do so is the connection exception listener.

On the other hand, I do hear your point about the rest of the sessions being closed due to
an error in just one session. It's not ideal, but given the limitation in JMS seems like a
necessary evil.

It's probably better to for all the sessions to get canned and recreated than just one session
silently failing and the application not knowing about it. From that perspective, I think
the current behaviour makes sense.

> Exception handling logic is incorrect in AMQConnection.java
> -----------------------------------------------------------
>
>                 Key: QPID-3234
>                 URL: https://issues.apache.org/jira/browse/QPID-3234
>             Project: Qpid
>          Issue Type: Bug
>            Reporter: Rajith Attapattu
>
> IMO there are two issues here.
> 1. The exception listener gets notified of session level exceptions.
> 2. A session level exception causes the connection to be closed along with the other
sessions.
> 1. We shouldn't notify the connection's exception listener when there is a session level
error. The JMS API doc clearly states,
> "If a JMS provider detects a serious problem with a Connection object, it informs the
Connection object's ExceptionListener, if one has been registered. It does this by calling
the listener's onException method, passing it a JMSException argument describing the problem.
"
> So certainly execution exceptions which only invalidates the session should not be notified
via the exception listener.
> 2. Going further if one looks at the AMQConnection.java exceptionReceived() method,
> It seems that an execution exception can in fact close the underlying connection (and
the rest of the sessions) due to the following piece of logic.
> if (hardError(cause))
> {
> closer = (!_closed.getAndSet(true)) || closer;
> { _logger.info("Closing AMQConnection due to :" + cause); }
> }
> Digging further for any AMQException hardError method will return true.
> Therefore we need to rework that piece of code.

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