[rabbitmq-discuss] Exchange disappear

[Rosa, Andrea]

Hi Marek

Thanks for your help

> -----Original Message-----
> From: Marek Majkowski [mailto:majek04 at gmail.com]
> Sent: 24 November 2011 10:23
> To: Rosa, Andrea
> Cc: rabbitmq-discuss at lists.rabbitmq.com
> Subject: Re: [rabbitmq-discuss] Exchange disappear
> 
> Hi,
> 
> On Wed, Nov 23, 2011 at 18:02, Rosa, Andrea <andrea.rosa at hp.com> wrote:
> > I have got a problem using the py-amqplib as client (version 0.6.1),
> It’s
> > more likely that my problem is in the client library but just to be
> 100%
> > sure I will ask to you to confirm my idea and maybe you could also
> give me
> > some aextra information to fix it.
> >
> > I have got this exception in my client log file :
> >
> > AMQPChannelException: (404, u"NOT_FOUND - no exchange
> > 'a61f445d611d4f40a972d1f0c5449c77' in vhost '/'", (60, 40),
> > 'Channel.basic_publish')
> 
> `basic_publish` must be run against an existing exchange. If the
> exchange
> is not available - RabbitMQ will complain and abruptly close an amqp
> channel.
> 
> Make sure the exchange exists at that point - maybe put
> `exchange_declare`
> before the `publish` ?
> 

I am sure that the publish command is called after the exchange_declare, because I can see the process work correctly for the 95% of my messages, but sometimes I have got this error.
Maybe some race condition?


> > And after that this error
> >
> > AMQPConnectionException: (503, u"COMMAND_INVALID - second
> 'channel.open'
> > seen", (20, 10), 'Channel.open')
> 
> This looks like a client library issue. Not many AMQP client libraries
> know
> how to behave after an error ocurred.
> 

> > The strange thing is that I can see the exchange in rabbitmq server.
> 
> This is quite unlikely. Maybe you checked at different point in time?
> Maybe the exchange was `auto_delete=True` ?
> 
> You can verify that using `rabbitmqctl list_exchanges`, or even better,
> using rabbitmq management plugin.

Yes, I agree with you maybe I check at different point of time.
The exchange has auto_delete=true, so maybe a possible scenario could be:
1 try to publish a message 
2 the exchange is not yet created
3 second attempt to publish a message which generates the second exception (503)
4 the message is not published and the exchange is created. 
I verified also that that exchange has not a binding.

> 
> Hope that helps,
>     Marek

Yes thanks!
--
Andrea