[zeromq-dev] detecting messages being dropped on a PUB socket?

[Mark Botner]

This page is empty for me:
http://api.zeromq.org/master:zmq-socket-monitor-versioned


Mark

On Wed, Dec 9, 2020 at 5:28 AM Luca Boccassi <bluca at debian.org> wrote:
>
> On Wed, 2020-12-09 at 11:30 +0100, Francesco wrote:
> > Hi Luca,
> > sorry to jump into this thread: but
> >
> > > We have added queue stats capability to socket monitors last year,
> >
> > Any documentation is available for this new feature?
> > I could not find any at http://api.zeromq.org/master:zmq-socket-monitor
> >
> > Thanks!
> > Francesco
>
> https://github.com/zeromq/libzmq/blob/master/doc/zmq_socket_monitor_versioned.txt
>
> > Il giorno mer 9 dic 2020 alle ore 11:24 Luca Boccassi <bluca at debian.org> ha scritto:
> > > On Tue, 2020-12-08 at 22:05 +0100, Arnaud Loonstra wrote:
> > > > Hey all,
> > > >
> > > > I might me missing something but is there any way of detecting messages
> > > > being dropped due to the high watermark on a PUB socket?
> > > >
> > > > It's clear how to do this is on a socket that blocks in the mute state,
> > > > but dropping message on mute is not?
> > > >
> > > > for example:
> > > >
> > > > // test hwm
> > > > sock_t *push = zsock_new(ZMQ_PUB);
> > > > zsock_t *pull = zsock_new(ZMQ_SUB);
> > > > zsock_set_rcvhwm(pull, 100);
> > > > zsock_set_sndhwm(push, 100);
> > > > zsock_set_sndtimeo(push,0);
> > > > zsock_bind(push, "inproc://test");
> > > > zsock_connect(pull, "inproc://test");
> > > > zsock_set_subscribe(pull, "");
> > > > zclock_sleep(10);
> > > > int rc = 0;
> > > > int count = 0;
> > > > while( rc == 0 && count < 10000) {
> > > >      rc = zstr_send(push, "BOE");
> > > >      count++;
> > > > }
> > > >
> > > > The count will be 10000 due zstr_send dropping messages but returning 0;
> > > > If we then receive the buffered messages we wil receive 20 messages
> > > > (rcvhwm + sndhwm)
> > > >
> > > > int count2 = 0;
> > > > char *m = "";
> > > > while ( m )
> > > > {
> > > >      char *m = zstr_recv_nowait(pull);
> > > >      count2++;
> > > > }
> > > >
> > > > Rg,
> > > >
> > > > Arnaud
> > >
> > > There is no deterministic way, and when you think about the conditions
> > > that might cause that to happen, it makes sense that there isn't.
> > >
> > > We have added queue stats capability to socket monitors last year,
> > > which will give you some insights - but it's of course asynchronous and
> > > best-effort, and thus useful for debugging and statistics but not for
> > > making logic decisions.
> > > The OS should provide you with data about the state of the underlying
> > > network interfaces/buffers.
> > >
> > > _______________________________________________
> > > zeromq-dev mailing list
> > > zeromq-dev at lists.zeromq.org
> > > https://lists.zeromq.org/mailman/listinfo/zeromq-dev
>
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