[rabbitmq-discuss] Recovery after heartbeat error

[Ioannis Foukarakis]

Thank you for the prompt reply Tim!

Yes, I expected that the channel would wait for a proper close and then
shut down. I was concerned whether that might leave "garbage" in memory,
but if I can just throw away all connections and channels it won't be a
problem.

Again, thank you very much!

On Thu, Mar 7, 2013 at 3:59 PM, Tim Watson <tim at rabbitmq.com> wrote:

> And .... looking at the title of the post (I got lost in the details and
> forgot) ....
>
> If a heartbeat error/timeout has occurred, then definitely just throw away
> all the channels for the connection - they're done and attempting to close
> them is the wrong thing to do in that situation.
>
> Cheers,
> Tim
>
> On 7 Mar 2013, at 13:58, Tim Watson wrote:
>
> > On 7 Mar 2013, at 13:28, Ioannis Foukarakis wrote:
> >> [snip]
> >> However, if I disconnect from the network, channel.close() blocks.
> >
> > Yes, this is *normal* behaviour for a networked application... When you
> pull the network cable (or take whatever equivalent action disconnects from
> the network) then the AMQP channel.close protocol has a slight problem. The
> client sends 'close' and waits for the server to respond with 'close-ok' -
> but if the server is gone, what then!? Usually the client then blocks until
> the operating system 'notices' that the peer socket is gone (because
> transmission retry limits have been exhausted, tcp keep-alives are enabled,
> etc). There are various conditions that determine this 'delay' and it can
> take up to 30 mins with some operating systems' default TCP configuration,
> before the application is notified with ETIMEDOUT. This exception occurs on
> the connection object, i.e., when the network failure is finally noticed it
> forces the connection to close. The channels will also be closed by the
> client (when it notices that the connection has been terminated).
> >
> >> Should I avoid trying to close channels? Is there a better solution for
> handling network errors?
> >>
> >
> > Yes, if you knew for certain there has been a network failure, then you
> should skip closing channels. The shutdown signal means that the 'other
> end' has closed so calling a synchronous AMQP method like channel.close
> after than is always going to block.
> >
> > If you have a very unreliable network then just rely on the heartbeats
> to terminate the connection (and therefore the channels) in a timely
> fashion. If you *need* to close channels more often than that, then you
> might need to put some kind of timeout around the channel.close() call.
> >
> > Cheers,
> > Tim
>
> _______________________________________________
> rabbitmq-discuss mailing list
> rabbitmq-discuss at lists.rabbitmq.com
> https://lists.rabbitmq.com/cgi-bin/mailman/listinfo/rabbitmq-discuss
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.rabbitmq.com/pipermail/rabbitmq-discuss/attachments/20130307/fd84c0af/attachment.htm>