Re: [mosquitto-dev] A mosquitto's design suboptimization case in our use

[Ian Craggs <icraggs@xxxxxxxxxxxxxxxxxxxxxxx>]

Strange.  I was under the impression that Mosquitto was using a 
non-blocking DNS lookup package already.

Ian

On 11/03/2015 06:50 PM, Roger Light wrote:
> Hi Felipe,
>
> The bridge connection should be non-blocking - with the exception that
> it uses getaddrinfo for lookups, which will block in the case that the
> DNS isn't available. I imagine that this is where problems are being
> introduced for you. You could test this by setting a IP address
> instead of a host name for your bridge connection.
>
> Workarounds could be setting a low timeout on your DNS lookups or
> installing a local caching DNS server.
>
> The real solution is of course to use asynchronous DNS lookups which
> is something that will be implemented in a future version.
>
> Cheers,
>
> Roger
>
>
>
> On Tue, Nov 3, 2015 at 5:59 PM, Felipe Lavratti <felipelav@xxxxxxxxx> wrote:
> > Hello!
> >
> > I'd like to share a design sub-optimization issue related to the Mosquitto
> > broker implementation pattern where no parallelism is used, and ask for any
> > opinions and insights about it.
> >
> > We run the mosquitto broker inside a network node that plays the central (or
> > coordinator) role of the given network. Every systems protocols runs on top
> > of the MQTT and uses the central node and this network is self contained, it
> > doesn't need external internet access to proper operate.
> >
> > The Mosquitto broker running in the central node have a bridge connection to
> > a remote broker for low priority data transfer.
> >
> > What I see as an issue, in our use case, is that under very poor internet
> > connection, the bridge takes considerable long time to connect (and
> > sometimes it never connects) turning the broker unresponsive during this
> > period, which will bring all local and high priority services to
> > degradation.
> >
> > What do you guys think of that?
> >
> >
> >
> > --
> > Skype: felipeanl
> >
> >
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--
Ian Craggs
icraggs@xxxxxxxxxx                 IBM United Kingdom
Paho Project Lead; Committer on Mosquitto