[zeromq-dev] max PUB/SUB topics

[Brian T. Carcich]

I duplicated Benjy's results (libzmq 4.2.3; master from Github)

  https://github.com/drbitboy/test_0mq_subscribe_limit

That is, on starting pub_env and sub_env, in either order, sub_env only
picks up envelopes 512, 511, and 1023 - N.B. sub_env subscribes to
envelopes 24 through 2600, inclusive, but normally does not not receive any
envelope above 1023.

HOWEVER, I did also stumble onto another odd behavior:  if pub_evn and
sub_env are running, and I kill pub_env and restart it, then sub_env picks
ups 512, 1024, 1536, and 2048, but not 511, 1023, 1535 or 2047.

Brian Carcich

On Tue, May 14, 2019 at 4:02 AM Bekritsky, Benjamin via zeromq-dev <
zeromq-dev at lists.zeromq.org> wrote:

> Justin,
>
>
>
> Thanks for the guidance, but I set the HWMs to 0 and neither application
> crashed. I also played with changing the HWMs to 2048 and am still
> encountering the same issue.
>
>
>
> I then subscribed to “all” and received the messages from all the topics
> (0-1024);
>
>
>
> It seems as though it is limiting the number of subscriptions to 1000. If
> I subscribed from 20 -1024, I get topics 20 – 1019.
>
>
>
> I am using lib 4.2.3 and the publisher and subscriber on the same Ubuntu
> box.
>
>
>
> Thanks,
>
> Benjy
>
> *From:* zeromq-dev <zeromq-dev-bounces at lists.zeromq.org> *On Behalf Of *Justin
> Karneges
> *Sent:* Tuesday, May 14, 2019 7:10 AM
> *To:* Jamie Stewart via zeromq-dev <zeromq-dev at lists.zeromq.org>
> *Subject:* Re: [zeromq-dev] max PUB/SUB topics
>
>
>
> [External Email]
>
> Hi,
>
>
>
> Subscribing sends a message to the publisher. I believe you're hitting the
> default high water mark, and subscription messages are getting dropped.
>
>
>
> If I'm expecting lots of subscriptions, my rule of thumb is to set
> SNDHWM=0 on the SUB socket and RCVHWM=0 on the PUB socket. This way the
> application will sooner die than lose a subscription message.
>
>
>
> Justin
>
>
>
> On Mon, May 13, 2019, at 10:06 AM, Bekritsky, Benjamin via zeromq-dev
> wrote:
>
> I am using libzmq and setting up topics using binary data. In other words,
> my topic is the first 2 bytes of my message.
>
>
>
> I subscribe by setting a and b to the values I’m interested in:
>
>         for (uint16_t i = a; i <= b; i++)
>
>         {
>
>                 d = zmq_setsockopt(sub_socket, ZMQ_SUBSCRIBE, &i, 2);
>
>                 if (d)
>
>                 {
>
>                         printf ("E: subscription failed: %s\n", strerror
> (errno));
>
>                         return -1;
>
>                 }
>
>         }
>
>
>
> My publisher publishes like this:
>
>                 string incoming_string = " this message";
>
>                 incoming_string.insert(0,1,i>>8);
>
>                 incoming_string.insert(0,1,i%256);
>
>
>
>                 int     rc = zmq_send(pub_socket, incoming_string.c_str(),
> incoming_string.size(), 0);
>
>
>
> I can’t seem to subscribe to more than 1000 topics (values 0x0000 –
> 0x03e7). From what I understand, thousands of topics should be available.
>
>
>
> Any guidance would be helpful.
>
>
>
> Thanks,
>
> Benjy
>
>
>
> Benjamin Bekritsky
>
> c/o Zebra Technologies
>
> 2 Negev St. (Motorola Building)
>
> 4th Floor
>
> Airport City 7019900
>
> Israel
>
>
>
>
>
>
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