[zeromq-dev] max PUB/SUB topics

[Bekritsky, Benjamin]

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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