Hi Karl,
I did some more tests, and you are right, it takes 16 minutes before the client
discovers it lost the connection with eh broker and disconnects.
This is what I see on the client when I use netstat -an:
[
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address Foreign Address State
tcp 0 0 0.0.0.0:22 <http://0.0.0.0:22> 0.0.0.0:*
LISTEN
tcp 0 0 192.168.5.3:22 <http://192.168.5.3:22>
192.168.5.50:65489 <http://192.168.5.50:65489> ESTABLISHED
--->tcp 0 13061 192.168.5.3:33225 <http://192.168.5.3:33225>
192.168.5.5:1883 <http://192.168.5.5:1883> ESTABLISHED
I send subscribe messages every 10 secs, the Send-Q is getting bigger as nothing
gets acknowledged by the broker.
After 16 minutes I see this:
netstat -an
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address Foreign Address State
tcp 0 0 0.0.0.0:22 <http://0.0.0.0:22> 0.0.0.0:*
LISTEN
-->tcp 0 1 192.168.5.3:33226 <http://192.168.5.3:33226>
192.168.5.5:1883 <http://192.168.5.5:1883> SYN_SENT
Connection gets a reset, and then the loop() becomes something else than 0 and
escapes.
The settings on my Linux client determine how long it takes before a connection
is considered lost. It looks I might have to tweak these settings a bit
to detect a lost connection sooner.
Thanks,
Rene
On Fri, Dec 13, 2013 at 5:51 PM, Karl Palsson <karlp@xxxxxxxxxxxx
<mailto:karlp@xxxxxxxxxxxx>> wrote:
How long are you waiting before deciding that it doesn't work? You might
have to wait for a
TCP connection to timeout before the loop will fail, depending on your OS
and network stack.
There've been a couple of changes (long ago) that helped propagate this up,
but pulling the
plug on an intermediate cable, so no link detection triggers socket cleanup
or anything can
really take a while.
Cheers,
Karl P
On Fri, Dec 13, 2013 at 04:49:48PM +0100, Rene Kogels wrote:
> Thanks Nick. But still, loop() will not detect this. At least not with my
> code, it will stay in the mosq_client.loop==0 loop when the connection to
> the broker is lost. When I shut down the broker normally (service mosquitto
> stop) the loop is stopped, and it tries to reconnect.
>
> Code (part):
>
> #Setup mosquitto client config
> mosq_client = mosquitto.Mosquitto("client1")
>
> #Connect mosquitto client; if we cannot connect, we will notice later with
> mosq_client.loop!=0
> mosq_client.connect("some host")
>
> #Endless loop
> while 1:
>
> while mosq_client.loop()==0:
> #Put some code here to read serial port to get some data
>
> #Publish it to the broker
> mosq_client.publish("serial/data", serial_data)
>
> #If we are here, we lost the connection with the mosquitto broker, so
> sleep first and then try to reconnect.
> print("No connection with broker. Sleeping before retrying...")
> time.sleep(10)
>
> print("Trying to reconnect")
> mosq_client.connect("somehost")
>
>
> Rene
>
>
> On Fri, Dec 13, 2013 at 4:17 PM, Nicholas O'Leary wrote:
>
> > Hi Rene,
> >
> > if the broker goes away, the tcp layer will notify the client side that
> > the connection has been lost and the usual connection-lost processing will
> > occur within the client.
> >
> > Regards,
> > Nick
> >
> >
> > On 12 December 2013 20:09, Rene Kogels wrote:
> >
> >> Hi all,
> >>
> >> I have a question about the behaviour of a python program that publishes
> >> data, but to a broker that lost its network connection after a while. The
> >> loop() function will probably not detect this as it will only detect
> >> changes on the network socket caused by the broker. In this case the
broker
> >> could not tell the publisher it lost the connection.
> >>
> >> Will the publisher keep sending data, assuming there is a broker? Or will
> >> it detect somehow the broker is gone (TCP does not get an ack)? Will the
> >> publish function block?
> >>
> >> Thanks,
> >> Rene
> >>
> >>
> >>
> >> --
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> >>
> >>
> >
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