mosquitto-users team mailing list archive

[Rene Kogels <renekogels@xxxxxxxxx>]

No, I use the default settings for the client (keepalives=60). On the
broker I didn't change anything in the config.
Maybe I should explicitly set it to 10 sec for example to see if that makes
a difference. Let me run some more tests....


On Sat, Dec 14, 2013 at 9:16 PM, Karl P <karlp@xxxxxxxxxxxx> wrote:

> Note still, mqtt keepalive should catch this too.  Had you disabled
> keepalives? or was your mqtt keepalive set even longer?
>
>
> On 12/14/2013 07:09 PM, Rene Kogels wrote:
>
>> 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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>>
>>