On Tue, Jul 6, 2010 at 9:52 AM, Martin Lucina <m...@kotelna.sk> wrote: > elliso...@gmail.com said: >> I have run into this many times. The issue is that the SUB socket >> doesn't get the messages until it actually connects: >> >> If the PUB starts before the SUB, the PUB will start broadcasting >> before the SUB starts and the SUB won't get those messages that were >> sent before the SUB connects. A PUB socket is like a radio broadcast. >> If you aren't listening, you don't get the messages. >> >> BUT (this is more subtle). If the SUB starts before the PUB, you will >> still miss messages. This is because it takes a little bit of time (I >> think 0.1 sec) for the SUB socket to realize the PUB socket has >> started. In that short time interval, the PUB socket has already >> started sending and you miss a few. > > This should be a non-issue in the simple case where a user starts the > subscriber (process b in the example) 1st, then switches to another window > and starts the publisher (process a) 2nd.
It depends on which side does the bind and which does the connect. If the SUB socket does the connect you will still miss messages if you start SUB first. The SUB socket will attempts to connect every 0.1 seconds and during that time it will miss them. > There is a more subtle thing going on here though which is that in process > a zmq_send() is async so this just means "queue for sending". If you queue > quicker than the *actual* send to the network happens and call zmq_term() > you will lose outstanding data. Yep, but hopefully that will be fixed. > There's no real solution to this right now except adding a sleep(100) in > the publisher, or as Brian says using some other way to synchronize "Start > of data" and "End of data". > -mato > _______________________________________________ > zeromq-dev mailing list > zeromq-dev@lists.zeromq.org > http://lists.zeromq.org/mailman/listinfo/zeromq-dev > -- Brian E. Granger, Ph.D. Assistant Professor of Physics Cal Poly State University, San Luis Obispo bgran...@calpoly.edu elliso...@gmail.com _______________________________________________ zeromq-dev mailing list zeromq-dev@lists.zeromq.org http://lists.zeromq.org/mailman/listinfo/zeromq-dev
