[zeromq-dev] Polling issue. Socket blocking on SendMessage

Tobias Elbert tobias_elbert at hotmail.com
Wed Aug 3 17:18:45 CEST 2016

Hi all,

I am having an issue with a setup similar to the sample in the Pastebin link provided below. Basically I let the poller block for 2 seconds and every 6 seconds send out a heartbeat from within the polling loop. My understanding is that while I’m in the polling loop that it is safe to do sends/ receives on any of the sockets on the poller.

This works fine for a few hours but after 2-3 hours (sometimes can also go for a whole day without issues). I put a fully functioning sample on Pastebin:


For clarity, here the piece of code where the SendMessage call blocks indefinitely:


    if ((DateTime.UtcNow - lastHeartbeat).TotalSeconds > 5)
        ZmqMessage hbMessage = new ZmqMessage();


        Console.WriteLine("About to send Heartbeat {0}", DateTime.Now);
        // blocks here after a while:
        frontend.SendMessage(hbMessage); // blocks here

        Console.WriteLine("Sent Heartbeat {0}", DateTime.Now);

        lastHeartbeat = DateTime.UtcNow;

Note I am using v3.2.5 libzmq and its corresponding C# bindings.

Any input would be appreciated.

Thanks Tobias.

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.zeromq.org/pipermail/zeromq-dev/attachments/20160803/815fe9c0/attachment.htm>

More information about the zeromq-dev mailing list