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From Jeff Rose <j...@globalorange.nl>
Subject Re: ajax handling fast messages
Date Mon, 10 Jan 2011 11:02:49 GMT
On Sat, Jan 8, 2011 at 2:11 AM, Alex Dean <alex@crackpot.org> wrote:

> On Dec 14, 2010, at 9:48 AM, Jeff Rose wrote:
>
> > Hi Alex,
> >  Thanks for the response.  We looked into it a bit more based on your
> > suggestion, and we discovered that there is an error occurring when the
> > continuation is resumed in onMessageAvailable in AjaxListener.java.  It
> > looks like this onMessageAvailable handler is being called every time a
> new
> > message arrives on the queue, and then it is trying to resume a
> continuation
> > that has already been resumed, which causes an illegal state exception.
> > We've been trying to fix the bug  by checking first:
> >
> >   !continuation.isResumed()
> >
> > but we are still getting the error occasionally (although it does often
> get
> > all of the messages now).  This seems to be a pretty fundamental bug in
> the
> > AJAX support of ActiveMQ.  Definitely worth posting a ticket (although I
> > don't know where that is done).
>
> Jeff: I attached a patch to AMQ-3094 which I think fixes this problem.  A
> continuation can be in more states than just initial & resumed, so checking
> !continuation.isResumed() can still result in illegal state exceptions.  I
> changed your suggestion so AjaxListener only tries to resume a continuation
> "if( continuation.isSuspended() )".  Otherwise it buffers the message for
> delivery in the next poll (building on some code Dejan committed a few days
> ago).
>
> Let me know if you have time to test this patch, and if it solves the issue
> for you.  It looks good in my tests so far.
>
>
> https://issues.apache.org/jira/secure/attachment/12467757/all_messages_are_delivered_to_ajax_clients.patch


Hi Alex,
  I'm not able to apply your patch, either to the latest from SVN or to
revision 1052368 which is specified in the patch.  For example,
in MessageListenerServlet.java I don't have any reference to
the unconsumedMessages linked list.  Can you generate the patch against the
latest from SVN so I can give it a try?  I've got everything setup again to
test with my initial PHP and javascript configuration.

Thanks,
Jeff

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