Hello,
By adding an incrementReferenceCount and decrementReferenceCount to the
PrefetchSubscription::dispatch method I have fixed the null message
problem I was experiencing.
private void dispatch(final MessageReference node) throws
IOException {
try {
node.incrementReferenceCount();
final Message message = node.getMessage();
if( message == null ) {
return;
}
// Make sure we can dispatch a message.
if( canDispatch(node) ) {
MessageDispatch md = createMessageDispatch(node,
message);
dispatched.addLast(node);
node.incrementReferenceCount();
incrementPreloadSize(node.getMessage().getSize());
if( info.isDispatchAsync() ) {
md.setConsumer(new Runnable(){
public void run() {
onDispatch(node, message);
}
});
context.getConnection().dispatchAsync(md);
} else {
context.getConnection().dispatchSync(md);
onDispatch(node, message);
}
}
}
finally {
node.decrementReferenceCount();
}
}
Regards,
Marcus
-----Original Message-----
From: Hiram Chirino [mailto:[EMAIL PROTECTED]
Sent: 23 December 2005 07:37 PM
To: [email protected]
Cc: [email protected]
Subject: Re: svn commit: r358785 -
/incubator/activemq/trunk/activemq-core/src/main/java/org/activemq/broke
r/region/PrefetchSubscription.java
Hi Adrian,
doing a getMessage() before incrementReferenceCount() is dangerous since
the message could have been swapped out and the call to
getMessage() will return null.
Yes, I know there is a null check to see if the message is null, but
that should only happen if the message was expired. Right now I think
it's possible that we are going to have cases of where messages get
swapped out and this code is going to think that the message has been
expired.
Regards,
Hiram
On Dec 23, 2005, at 4:48 AM, [EMAIL PROTECTED] wrote:
> Author: aco
> Date: Fri Dec 23 01:47:47 2005
> New Revision: 358785
>
> URL: http://svn.apache.org/viewcvs?rev=358785&view=rev
> Log:
> Postpone incrementing of reference count and preload size, only after
> we are sure that the message will be dispatched by the current
> subscription. This is to prevent a memory leak type of scenario.
>
> Modified:
> incubator/activemq/trunk/activemq-core/src/main/java/org/
> activemq/broker/region/PrefetchSubscription.java
>
> Modified: incubator/activemq/trunk/activemq-core/src/main/java/org/
> activemq/broker/region/PrefetchSubscription.java
> URL: http://svn.apache.org/viewcvs/incubator/activemq/trunk/
> activemq-core/src/main/java/org/activemq/broker/region/
> PrefetchSubscription.java?rev=358785&r1=358784&r2=358785&view=diff
> ======================================================================
> ========
> --- incubator/activemq/trunk/activemq-core/src/main/java/org/
> activemq/broker/region/PrefetchSubscription.java (original)
> +++ incubator/activemq/trunk/activemq-core/src/main/java/org/
> activemq/broker/region/PrefetchSubscription.java Fri Dec 23
> 01:47:47 2005
> @@ -239,19 +239,19 @@
>
> private void dispatch(final MessageReference node) throws
> IOException {
>
> - node.incrementReferenceCount();
> -
> final Message message = node.getMessage();
> if( message == null ) {
> return;
> - }
> - incrementPreloadSize(node.getMessage().getSize());
> + }
>
> // Make sure we can dispatch a message.
> if( canDispatch(node) ) {
>
> MessageDispatch md = createMessageDispatch(node,
> message);
> dispatched.addLast(node);
> +
> + node.incrementReferenceCount();
> + incrementPreloadSize(node.getMessage().getSize());
>
> if( info.isDispatchAsync() ) {
> md.setConsumer(new Runnable(){
>
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