On Mon, 2018-04-16 at 18:25 +0200, Johnny Berentsen wrote: > 2018-04-16 14:35 GMT+02:00 Luca Boccassi <[email protected]>: > > > On Mon, 2018-04-16 at 13:54 +0200, Johnny Berentsen wrote: > > > 2018-04-02 15:30 GMT+02:00 Johnny Berentsen <johnny.berentsen@gma > > > il.c > > > om>: > > > > > > > Hi all > > > > <snip initial explanation> > > > > > > > > > > Now I have a vector with size 2500 of std::strings filled with > > > 4096 # > > > characters. Every ten seconds I loop through the vector and send > > > the > > > data > > > over a EPGM socket. If I go full throttle, only the first 1000 > > > messages are > > > received, but if I add a usleep(1) after each send, all messages > > > are > > > received. > > > > Default high water mark is 1000 messages, most likely the receiving > > side is too slow to process and so it starts dropping messages > > > > > > You're absolutely right. I was put off by the documentation that > said: > The default *ZMQ_SNDHWM* value of zero means "no limit". > > Shame on me for not trying though :/ > > I understand that setting the HWM is different depending on the usage > pattern. However, I can't find much information on the different > criterias > that should be considered. > I've come up with these: > Typical and max packet size, network restrictions, number of packets, > available memory, CPU > > My application will run on a LAN on modern PC's with >=8GiB memory, > up to a > few kB's per message and only a burst of a few thousand messages once > in a > while. What value is reasonable in such a case?
It mostly depend on your application and how quickly it can pull messages off the socket. So the only way is to try and test it. > I also tested with checking the return value of send() but it > returned true > regardless of sending or not. Are there other ways of being noticed > that > messages have been dropped? No, that's the whole point about pub-sub - if you don't want a lossy mechanism then you should use a different pattern. Or you can set unlimited water marks and deal with the unbounded memory usage. -- Kind regards, Luca Boccassi
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