[zeromq-dev] max PUB/SUB topics

[Justin Karneges]

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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